# Turning Tool And Facing Tool Questions



## Joe Pitz

Hello All, 

Since I do not have a DRO on my lathe or dial indicators.  What is the correct procedure for turning to a shoulder and then facing the shoulder.

I start out facing the end of the stock with the facing tool,  then I switch to the right hand turning tool to rough out the O.D. (this forces me to change the angle of the tool holder)  Then I have to switch to the facing tool again, which causes me to have to change the angle of the tool holder again.  When I attempt to then match the correct O.D. I have problems holding the same dimensions at the shoulder, or if I have to increase the depth of the shoulder I end up messing up the O.D.

Also question on the new tool holders,  Is is true that the new indexable tool holders have the geometry to both face and turn without having to change the tools?

Thanks

Joe


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## RJSakowski

When I have to turn to a precise shoulder, I grind my tool with an acute angle (around 75 deg.) and orient it so that I have relief both parallel and perpendicular to the spindle axis. That way I can both turn and face with the same tool setting.

I rough turn, stopping not quite at the face of the shoulder and when I am nearly at my final diameter, take a finish facing cut.  I then make my final finish cut on the diameter.  For diameter settings, I use the cross feed dial and mike when I get close.  I then make differential cuts based on the mike readings.  For the shoulder face, I set up a carriage stop or I set the compound up parallel to the spindle axis and use the compound dial to indicate position.


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## JimDawson

I assume you are using insert tools.  If you use a tool that has less than a 90 degree angle, you can face and turn with the same tool without moving the tool post.

I normally just use a cheap (from Harbor Freight) AR-8 brazed carbide tool and grind a little more clearance on the nose so the angle is less the 90 degrees.  I own a set of cheap insert holders, but I've only used them about 2 times.  I would rather just grind to shape I want for the job.


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## Joe Pitz

Thanks RJSakowski,

I have started learning how to grind hss tools,  let us just say, my efforts are not going good.  I watched tubalcain's videos, but he free hand grinds,  there is no way I am ready for that.  

Thanks

Joe


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## Joe Pitz

Thanks JimDawson, do you have a diamond wheel or do you use a green wheel?  I hear it is hard to grind carbide without chipping it?

Joe


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## RJSakowski

Joe Pitz said:


> Thanks RJSakowski,
> 
> I have started learning how to grind hss tools,  let us just say, my efforts are not going good.  I watched tubalcain's videos, but he free hand grinds,  there is no way I am ready for that.
> 
> Thanks
> 
> Joe


I free hand grind my tools as well.  It helps to mount the tool bit in a holder to give you a better grip and to better judge the angle that you are grinding.  You will get good at it with a little practice.  A final hone with a whetstone will give you a keen edge.

Bob


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## RJSakowski

Joe Pitz said:


> Thanks JimDawson, do you have a diamond wheel or do you use a green wheel?  I hear it is hard to grind carbide without chipping it?
> 
> Joe


I rough grind my carbide tools with my Carborundum  grinder and use a small diamond wheel to finish, honing with a diamond stone.  The carborundum grinding is brutal and leaves chips in the carbide, hence the final grind on the diamond wheel.  I do this because I don't want to use the diamond wheel for large removal of stock.  Not the best way but it works.


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## JimDawson

Joe Pitz said:


> Thanks RJSakowski,
> 
> I have started learning how to grind hss tools,  let us just say, my efforts are not going good.  I watched tubalcain's videos, but he free hand grinds,  there is no way I am ready for that.
> 
> Thanks
> 
> Joe





Joe Pitz said:


> Thanks JimDawson, do you have a diamond wheel or do you use a green wheel?  I hear it is hard to grind carbide without chipping it?
> 
> Joe



Free hand grinding just take little practice, keep in mind the tip and the left side of the tool ( for a right hand tool) is doing all of the work, everything else is just clearance.  The angles are not critical.  If the tool grind does not produce the desired result, then try again with slightly different angles.

While I do have a tool grinder with green wheels, I normally just use my cheap Chinese bench grinder with with a standard aluminum oxide gray wheel.  You just have to push a little harder.  On the other hand, I do a lot of things that aren't ''normal''  IMHO, as long as shop safety practices are observed, anything goes in machining.  There is no ''right way'' to do an operation as long as the part comes out the way you want it to. 
.
.


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## Joe Pitz

Thanks Jim and Bob,

I purchased 36" of 3/8" cold rolled steel square bar stock.  This is my practice material.  I will try free handing.

Joe


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## JimDawson

Joe, you might be better served by purchasing some 3/8 HSS tool blanks.  That way you can test your grind as you are learning.  Even after grinding tool bits for about 50 years, I still make a trip back to the grinder if the shape I ground doesn't do exactly what I want.


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## Joe Pitz

Jim, Currently I am having trouble getting the angles going the right way,  Once I start to get the hang of grinding I will switch to tool blanks
and then, as you say, be able to test out my grinding.

Good tip.

Thanks

Joe


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## JR49

Joe,  I would like to suggest two posts for you to read. I watched the Tubalcain and Halligan videos as well as others, and learned a lot from them. However, after reading these 2  posts, and lots of practice, I consider myself an excellent tool grinder (although I still don't even qualify as  a very novice machinist).  They are,  "Advanced tool sharpening for the lathe by Conrad Hoffman"  (find this post right here at the beginning of the Questions and Answers forum).  This one shows  the little tricks to help you grind freehand.  The other is on another forum,   http://www.chaski.org/homemachinist/viewtopic.php?f=44&t=76065  (hope its Ok to put that link )  Harold_V  Shows that the single biggest thing you can do for successful grinding is being able to see what you're doing, so, get rid of the tool rest (NOT THE SAFETY GUARDS), and hold the tool  below the centerline of the wheel.  Hope this helps,  JR49

EDIT,   I should add that Harold_V  talks a lot about using only the correct wheels for grinding HSS.  He is probably right, but I have had success using the wheels that came with my grinder


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## mikey

Joe Pitz said:


> I start out facing the end of the stock with the facing tool,  then I switch to the right hand turning tool to rough out the O.D. (this forces me to change the angle of the tool holder)  Then I have to switch to the facing tool again, which causes me to have to change the angle of the tool holder again.  When I attempt to then match the correct O.D. I have problems holding the same dimensions at the shoulder, or if I have to increase the depth of the shoulder I end up messing up the O.D.
> 
> Also question on the new tool holders,  Is is true that the new indexable tool holders have the geometry to both face and turn without having to change the tools?



It sounds like you're using inserted carbide tools, at least until you learn to grind HSS. If you wish to turn and face without turning the tool post then the* SCLCR* (RH tool) and *SCLCL* (LH tool) turning tools would serve you well. These tools have a *built in 5 degree clearance angle on the side and end* so that the tool will both turn and face with the shank of the tool held perpendicular to the work; no angle changes are required. They use both CCMT or CCGT inserts that come in a variety of grades and nose radii that allows you to cut almost any machinable material. The tool holders are standardized and made by many makers; I prefer SECO or Iscar but there are many others. Inserts are also made by many makers and are popular on ebay.

If you go this route I would choose a tool holder maker and download their literature on turning tools and inserts and then learn how to choose the insert you need.

If you go with HSS then things get more complicated because the various angles change depending on the material you are cutting. With no offense meant, I am going to suggest to you that relief and rake angles make a huge difference in cutting forces, cutting temperatures, finish and tool life. Getting it close is not as good as getting it right.

It is rather simple to grind a general use tool shape what will both face and turn with equal ease; all you need is to be sure that the angles at the tip are less than 90 degrees. That is, the angles between the side and end cutting edges need to be about 80-85 degrees to each other. This allows you the clearance you need to turn the OD or turn into a shoulder and face out without any of the edges rubbing against the work. Note that we are simply addressing tool shape here and are NOT talking about relief or rake angles. A worthy tool shape might be one that is halfway between a roughing tool and a facing tool.

As I implied, the relief and rake angles will differ with regard to the material you are cutting if you want optimal performance. However, you can choose angles that will work with most materials, though they will be a compromise. This would be well beyond the scope of this discussion so I will desist. Just keep in mind that with HSS tools you will, and should, change the angle of the tool (this is called changing the lead angle) to suit your purposes - more lead angle when possible to enhance finishes and less lead angle to reduce chatter and enable deeper cuts or to approach and cut/face a shoulder.

Anyway, look into the SCLCR/L tools - they will suit your needs very well.

Oh, and when you get to grinding HSS I suggest you choose 6061 Aluminum or 12L14 mild steel to practice on. These materials are hard enough to let you see how the tool is cutting (sizing accuracy, finish, chip shape, etc) and soft enough not to present a challenge when learning how tools and materials like to cut.


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## Joe Pitz

thanks JR49, great info,  I will check out the material you recommended, as I am having trouble with the tool grinding.

Joe


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## Joe Pitz

Thanks mikey,  great info on indexable tools and tool grinding angles,  everyone tells me the relief angles are not critical,  I will do some more research on grinding and in the mean time look for some good SCLCR and SCLCL tool holders.

Joe


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## mikey

Joe Pitz said:


> Thanks mikey,  great info on indexable tools and tool grinding angles,  everyone tells me the relief angles are not critical,  I will do some more research on grinding and in the mean time look for some good SCLCR and SCLCL tool holders.
> 
> Joe



Joe, you will find that the smaller the lathe and the smaller and harder the work piece, the more important those relief and rake angles (and nose radii) become. Cutting forces are a big deal when rigidity is limited and accuracy matters. You never mentioned which lathe you're using - would you share that? Not all lathes benefit from carbide, as I'm sure you know.


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## Joe Pitz

mikey, I started out with a 7x10 mini lathe from HF,  but I was so disgusted with the quality, I found an old Clausing 6316, just picked it up last week, so I am getting up to speed using it.  I guess I am using carbide currently as I don't know how to how to grind HSS,  I was going to stay with carbide, but after watching a bunch of videos and everyone telling me to use HSS, I started last night, attempting to grind,  I picked up some 3/8" cold rolled square bar stock, cut it up into tool  blank sizes.  I am now practicing.

Thanks

Joe


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## JimDawson

You'll get it figured out Joe.  Pretty soon, you'll have one of those Ah-haaaaa moments and it will all come together.


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## Joe Pitz

Thanks Jim

Joe


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## mikey

Joe Pitz said:


> mikey, I started out with a 7x10 mini lathe from HF,  but I was so disgusted with the quality, I found an old Clausing 6316, just picked it up last week, so I am getting up to speed using it.  I guess I am using carbide currently as I don't know how to how to grind HSS,  I was going to stay with carbide, but after watching a bunch of videos and everyone telling me to use HSS, I started last night, attempting to grind,  I picked up some 3/8" cold rolled square bar stock, cut it up into tool  blank sizes.  I am now practicing.
> 
> Thanks
> 
> Joe



That's a 12" lathe so you should have the power and rigidity to use carbide, especially if you can get the SFM into the range you need to use those tools effectively. Those SCLCR/L tools will work well for you, I think, and will get you up and running while you learn to grind your own tools ... and well beyond. 

I'm a HSS user and have been for a long time. For smaller lathes, like your 7X10, I wouldn't recommend carbide at all. Your Clausing is another story and you have the option of using HSS or carbide or both. With modern carbide insert and tool geometry the line between what works better is blurred. There are inserts with very sharp edges and positive tip geometry that approach HSS in effectiveness, especially for Aluminum.

In any case, as Jim says, you'll sort it out. I agree with using mild steel keystock to learn to grind tools - it is a skill well worth learning.


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## Joe Pitz

Thanks mikey, I appreciate all of the good info.

Joe


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## Joe Pitz

Joe Pitz said:


> [QUOTE="I normally just use a cheap (from Harbor Freight) AR-8 brazed carbide tool and grind a little more clearance on the nose so the angle is less the 90 degrees.  I own a set of cheap insert holders, but I've only used them about 2 times.  I would rather just grind to shape I want for the job.



Jim, could you show me an image or drawing of how you grind a little more clearance on the nose.  I set up my tile saw today and made an attempt to clean up some carbide brazed tips.  The tile saw did a pretty good job.  So later this evening I stopped at HF and picked up a diamond hone set.  I want to try your less than 90 degree modified AR-8 tool.

Thanks

Joe


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## JimDawson

Here is a picture of an out of the box AR8 brazed carbide.  This is the base tool used in the following examples.  The cheap HF tool bits will not cut right out of the box, clearance needs to be ground before use.  All of the grinding was done on a standard gray aluminum oxide wheel on a bench grinder.




This is one example, in this case the carbide has been ground to about 85 degrees and a bit more clearance ground on the supporting steel.




Another example of a highly modified bit with a chip breaker ground in with a diamond wheel in a Dremel.  This creates the little curly chips rather that the stringy mess without the chip breaker as above.




Another view of the same bit

And I have no idea what the 3 black dots are, on the side.  I couldn't see them with the naked eye.





and another view




I should note here that this tool was cutting just fine and had been for about an hour of cutting 4150,  Here is a picture of one of the parts that was cut with this tool.  As crappy as the tool looks, you can see the finish was just fine.  This started out life as a 1.25 dia chunk of 4150.




Here is the same tool on another job, that is a 3 inch dia chunk of 4150




Here is an AR8 ground into a threading tool


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## kingmt01

Nice wrote up Jim.

I read on here about threes guys grinding there cheap carbide tools so I have it a try. First I tried grinding the soft metal with a white stone which seems to slowly remove the carbide also but that isn't part of the plan. I then finished the shape on the diamond hone returning to the white wheel every time I got back into the soft metal. I then made a arbor to turn my diamond wheel & tried another tool on it. Both ways of making citing tools produced very nice cutting tools but shaping them on the hone was the fastest. 

I didn't remove anything on the top like Jim shows so I may have to try that next time. I have found that not only does my ground carbide tools cut better then the out of the box ones but they last longer also. 

One suggestion is once your close to the shape you want is to have the tool nice & cool so you can finish the tool in one holding at the stone because if you take small grinds you won't get the tool held just right when you start the grind again. On a hone it is easy to pick up the shape again.


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## Joe Pitz

Thanks Jim, that is amazing the flexibility that you get by grinding the carbide.

Joe


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## Strtspdlx

I'm a complete newbie when it comes to tool grinding. I have an atlas 10" and all I've ever used was hss. That being said I went with trial and error for grinding bits and seeing how they cut. I bought a ten pack of cobalt hss and wasted half of one to figure it out after watching tubalcains video. The most important thing I got from it is you want to present the cutting edge to the work. I
Make up my angles I've never once measured one and to this day I haven't had an issue. If I don't get the finish I want I stone the edge to round it and magically I get a good finish. All other variables aside learning to grind hss tooling is mainly trial and error I wouldn't worry about pretty right now. Make it work and once you figure out what works then you can pretty it up. All my grinding is free hand also. 


Regards-Carlo


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## Joe Pitz

Thanks Carlo,  you make it sound so easy.    Your advise makes a lot of sense.  I will keep on practicing.

Joe


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## Strtspdlx

Joe Pitz said:


> Thanks Carlo,  you make it sound so easy.    Your advise makes a lot of sense.  I will keep on practicing.
> 
> Joe


Just don't be afraid to mess something up. The only way I learn is the hard way. And the only way to get good at something is by doing it (experience)


Regards-Carlo


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## Tozguy

Joe, I definitely think that you will get comfortable with grinding tools because the eventual payback in enjoyment is tremendous.
It is not always easy to interrupt a job to sharpen the tool but once you have a taste of using a really sharp tool it will become second nature. A good magnifying glass will help you see what the work sees.

The following product might be worth a look for ease of sharpening.  I have no relation with the company other than being a happy customer. It was the ole 'cry once' principal but have had much pleasure using this tool ever since. http://bay-com.com/product-list.php?DIAMOND_TOOLHOLDER-pg1-cid35.html

Good luck, Mike


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## Joe Pitz

Thanks Tozguy,  the price is quite steep in the diamond tool holder, but I watched some of the videos, and with cobalt the performance is amazing.

Joe


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## Tozguy

Joe,
Some people have made their own tangential holders so that standard HSS, cobalt and even carbide bits can be used. The 'crobalt' bit from Bay-com is relatively inexpensive. In my case the purchase price of a Diamond LH and RH holder has long since faded from memory. Such a pleasure to use it has become my go-to holder.
Mike


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## Joe Pitz

Thanks Mike,  I have been looking at how others have constructed their tangential holders.  When I develop more skills I will attempt to make one myself.  But in the mean time I will have to save up for the Bay-Com set.

Joe


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## toolman

Joe, good luck with your endeavours! In my opinion, you are doing yourself a disservice using mild steel for practice because while you can get used to grinding shapes, you can't see how those shapes work in actual use.  I watch CL and eBay for lots of used hss bits and when you grind a bit, you can see how they cut instead of just looking at it. 
I'm not knocking your procedure at all, just throwing another option out there.


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## Joe Pitz

Toolman,  you have to understand, I am so new at tool grinding  that I am having problems getting the correct angles.  Once I get the tool to start looking correct, I will switch to tool blanks.  

Thanks

Joe


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## Strtspdlx

Joe Pitz said:


> Toolman,  you have to understand, I am so new at tool grinding  that I am having problems getting the correct angles.  Once I get the tool to start looking correct, I will switch to tool blanks.
> 
> Thanks
> 
> Joe


I agree with toolmans post. You can worry about the angles and this and that all you want. It'll only leave you more unhappy when you take all that time and care to make the tool perfect and it doesn't give you the desired results. 
I would keep that in the back of your head every time you grind a mild steel blank as you cannot use it to see what changes effect certain things on material. eBay has cheap blanks and trust me it takes a lot to use up a whole blank and for under $10 you can get 5-6 in smaller sizes. 
At the end of the day it's your choice but I'd strongly advise you to reconsider practicing on mild steel and start grinding tool steels and see what they do. 


Regards-Carlo


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## Joe Pitz

Thanks Carlo,  I do have a few tool blanks around I will try on these, tonight after work.

Joe


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## Bill C.

Joe Pitz said:


> Thanks JimDawson, do you have a diamond wheel or do you use a green wheel?  I hear it is hard to grind carbide without chipping it?
> 
> Joe



Green wheels were the only ones I used.  I never had a bit to chip while sharpening. I had it pop off when my favorite bit was to small to use.


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## Bill C.

If I was making parts for a one of my projects that screwed together I would undercut the intersection between the face and turned diameter so both parts will screw tightly together.  But if the print calls for a square shoulder then I use a left hand facing bit,( if the compound slide is 30-45 degrees) and lock the carriage clamp and taking small cuts with or without power feed slowly remove the remaining material until it is cleaned up.  I like power feed but it must be set to the smallest setting because as the tool moves out it can leave spiral tool marks requiring hand feeding to cleanup.

Are you using a quick change tool-holder? I started out with what they call a lantern tool holder , the old standard of it's day, with several tool-holders then the next shop had QC tool-holders.  Seems I could have used a extra holder or two for a complex part.  If your lathe doesn't have a carriage clamp consider carriage stops to butt up to.   I have used a "C" clamp and short piece of flat stop as a stop, granted not the best but got to use what you have sometimes.


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## markknx

I like to use the tool rest it helps keep the tool still. you can also put lines for the angle you want to hold the bit at. Or if the tool rest is larger you can use a bevel square along the edge as a guide. I did the former when these guys were schooling me on grinding lathe bits. Just some thoughts, and ideas I was given when I was learning (not that I'm a pro) But like Jim said there will be that aha moment and this is one of those things that hearing many different ways of doing it may help trigger that moment. Good luck and keep trying.
Mark


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## Tozguy

Just a few pointers on grinding that I have read and then proven to myself with time.
The grey wheels that come with most grinders are wretched. They will turn you off grinding in no time. For HSS grinding get a white alox wheel of the right spec. it cuts HSS almost like butter.
For carbide I use a green sica 80 grit wheel. Its slower going but I have never had a problem with chipping.
All edges are finished with an EZ Lap hone in 1200 grit(extra fine).

I admire the people who can grind freehand. In my case the it was too frustrating to be almost done when a slip up would ruin the job. It was much easier than I thought to make a solid tool rest attached to the bench and results made it well worth the effort. With the control afforded by a solid tool rest it much quicker to match angles and touch up a tool with a minimum of grinding.

It is also imperative to keep the wheel dressed for proper grinding. Diamond dressers are best for this and they need a solid rest to be used properly.


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## Joe Pitz

Thanks Jim for the info on the green wheels.  

Thanks Bill C,  For the perspective on shoulder cutting,  I do use a quick change tool post,  I have seen tubalcain use the lantern tool post.
My lathe came with the Quick change tool post, and a few holders.  When I just had my mini lathe I picked up a quick change for it as well.
My lathe also has a carriage lock and I have been getting into the habit of using it.  The mini lathe did not have one, so I have to remember to use it.

Thanks Mark,  It is interesting to hear that different people use the tool rest and some do not.  I also watch Tom Lipton's OXTools videos and he uses the tool rest as well.

Thanks all

Joe


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## Joe Pitz

Thanks Tozguy for the info on the grinding wheels,  I will look for the alox and I have been looking to purchase a green wheel as well.

Joe


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## Strtspdlx

If you have any questions in grinds or would like to see pictures I can snap a few of my more commonly used tools just to give you an idea. I have one tool bit in my holder that I use for turning and facing. One end is for left hand turning the other is for right hand Turning and facing. While they may not be perfect grinds they get the job done for me and give
Me good finishes and fairly decent roughing cuts. Something like .060-.080 depending on material is the most I've tried using the tools I've ground so far. 


Regards-Carlo


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## Joe Pitz

Carlo, I would love to see some pics of proper tool grinds for a tool that does both turning and facing, and any other that you care to share.

Thanks

Joe


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## Tozguy

Not meaning to pre-empt Carlos as I would like to see his answer but his is kinda neat.


Many have gone before us for a long time now so knowledge on tool geometry is readily available. If you have ground a tool according to the 'book' and it doesn't work well there can be many other causes than the tool. A newcomer to grinding would be better off learning to set up and use a bench grinder properly than experimenting with unorthodox angles, radius' and  relief on the tools from the get-go. Devote sufficient time to learning about grind wheel materials, how to install them, maintain them,  and use them. It will be a revelation I garantee it.
http://www.conradhoffman.com/advancedsharp.htm


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## Joe Pitz

Thanks for the tip Tozguy,   Didn't I hear someone say you had to be a millionaire to be a home machinist.  There are way too many tools to purchase at the end of the money   I guess as I will have to start making tools in order to gain some experience. 

Thanks

Joe


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## JimDawson

Joe Pitz said:


> Thanks for the tip Tozguy,   Didn't I hear someone say you had to be a millionaire to be a home machinist.  There are way too many tools to purchase at the end of the money   I guess as I will have to start making tools in order to gain some experience.
> 
> Thanks
> 
> Joe



Nah, just look for the deals, it just takes  little time and money to get set up.  I've owned boats and airplanes, a machine shop is by far cheaper, and it will actually support it's self.


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## Joe Pitz

Jim,  yes, you do this for a living,  how can a home machinist recoup some of the investment?  Do work on the side?
I would love to hear some ideas.

Thanks

Joe


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## Strtspdlx

Well here's a picture of
My most commonly used tool. As I had said before I watched some videos and measured some angles sometimes and I never got the results I desired. My tools may not be correct or at an exact angle but they work for my purposes. The first picture of bar is a piece of unknown ss I turned the next is mild steel. Hopefully this helps if not let me know and I'll try to answer to the best of my knowledge. 
	

		
			
		

		
	













Regards-Carlo


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## JimDawson

Joe, I actually don't do machine work for a living, in fact I've never even called myself a machinist.  I'm really just an old millwright that knows how to turn a crank on a machine.  That is not to say that I don't sometimes do a small job here and there.  That money normally goes back into the kitty to buy more toys.  The reason I have machine tools (beside the fact that I enjoy making chips) is to support my ''real job'' which is industrial software & control systems,  machine design & fabrication, and contract industrial maintenance (or anything else I can make a buck at ). 

Much of the small work comes from Craigslist.  I check the Gigs section a couple of times a day, there is always someone wanting a widget built or repaired.  I would think in your area, there might be even more of that.  Just Monday I picked up a gig for a 20 piece order of prototype store displays from Craigslist.  That project will be aluminum, wood, and glass.  It will require some CNC work, but also could be done on a manual machine.

Living in a rural farming area, I also pick up some equipment repair work.  In addition to that, networking with a wide cross section of people has landed a number of jobs.  I'm about half crazy, and will tackle anything.    I have been known to bid jobs without a clue of how I was going to do it, and I usually come out OK on them.

So yeah, there is side money to be made.


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## Joe Pitz

Carlo, thanks for the quick response of the pics.  I like the close ups.  I like how you grind the large reliefs on the tool.
I have to keep on practicing.

Jim, Thanks for the tips,  when I get more skills I will definitely look on craigslist for odd jobs.  

Looks like you have a very diverse background.  

If I was younger I would definitely want to get into machine design, micro-controller based or processor based.
I love to mix software and hardware.

Thanks

Joe


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## mikey

I think using mild steel keystock to learn how to grind tool bits is a great practice. New guys need to learn to how to move their hands and mild steel makes this simple to do. And that tool will cut, although the edge won't last long. The important thing is to learn how to shape the tool to its intended purpose. Tool geometry is important and when you understand it you can make that tool do pretty much whatever you want. You can use a bench grinder or a belt sander to grind tools but you need to know what you're grinding and why you're grinding it the way you are. 

With enough power and rigidity you can make almost any HSS tool work. Will it work as well as a properly ground tool with the correct angles for that material? I submit that it will not. 

Here is a roughing tool intended for use on steel, just off the belt sander and ready for honing:




This tool will work fine for steel and most harder materials but it won't work as well on, say, aluminum as a tool intended for aluminum - all the angles are wrong and the results will show this. Moreover, if you use this tool on a small lathe with limited rigidity and power you will run into the limits of the lathe much sooner than if you use this tool on a larger lathe. Cutting forces matter; accordingly, so does the tool's geometry. This tool would look different if I were to use it on a little 6X lathe or Sherline lathe because I need to account for the limited power and rigidity of those machines. And this is just a rougher; a finishing or facing tool would look very different since it would be ground to suit it's purpose. The relief, side rake and back rake angles would also differ from the roughing tool and they would be further adjusted to suit specific materials.

I'm not trying to be argumentative or insulting in any way. I just feel that there is a rhyme and reason to tool geometry and as I said before, getting it close is not as good as getting it right. The bottom line is that each tool is ground to suit its purpose and the material it is intended to cut. While you can also make general purpose tools that will work for most materials they do involve compromises that we need to understand and accept.


----------



## JimDawson

Joe Pitz said:


> If I was younger I would definitely want to get into machine design, micro-controller based or processor based.
> I love to mix software and hardware.



Younger?   He!!, I'm older than you are.   At our age, that just means more experience to draw on.


----------



## Tozguy

Joe, if you think grinding stuff is expensive wait until you need more measuring equipment, collets, etc.
I look at it this way; it is very inexpensive medication. So much the better if you can make some dough back.
Mikey mentionned Sherline, hope that you don't mind yet another article link but this one seems tailored for beginners.
http://www.sherline.com/grinding.pdf


----------



## Joe Pitz

JimDawson said:


> Younger?   He!!, I'm older than you are.   At our age, that just means more experience to draw on.



LOL,  You are correct Jim,  My wife will not let me quit my day job to pursue a new job,  but I sure can have a part time job.

Joe


----------



## Joe Pitz

Thanks Tozguy,  I will check out the article,  I hate to tell you but Sherline is about 30 minutes from where I live.  I have called them but never went by there showroom,. There stuff is good quality, but way too small for what I want.

Yes,  When I was growing up my neighbor was a machinist, when he retired he gave me a complete set of Starrett mics, depth gauges and telescope gauges.

When I was going to school I worked in a gas station and one night someone got into my tool box and stole my test equipment.  I was heart broken.  Still to this day I wish I had that measurement gear.

Joe


----------



## Joe Pitz

Thanks mikey,  as usual great information to take to heart.  I will work on my rake and relief angles when I can get good shape going.

Joe


----------



## mikey

Joe, keep in mind that you are grinding the relief angles at the same time as you are grinding the shape of the tool. That is, when you grind the side cutting edge angle you are also cutting the side relief angle at the same time. When you grind the end cutting edge angle you are cutting the end relief at the same time. The relief angles are set by the angle of your tool rest. If you choose to free hand the tool then your angles will be approximate at best. Your lathe has enough power for a general angle to work but for those guys with small lathes this is going to be a crap shoot. It is better to have a tool rest/table  that can be set to a precise angle and locked down. 

As I said, I agree with using mild steel keystock to learn to grind tools. You are trying to understand how all the angles on a tool are cut. Relief angles are cut as above, while rake angles simply involve a straight push into the wheel or belt; it is much easier and more accurate to do this when you have a tool rest that can be locked at accurate angles. Once you understand how the various angles are cut then you need to learn how those angles function and how they affect cutting forces so that you can alter them to suit your needs. For example, if you need a fine finisher then you can increase side relief to provide a sharper interface and better clearance at the cutting edge and increase back rake to focus the cutting forces at the tip of the tool. Then you can use a slightly larger nose radius to create a really fine finish. None of this is difficult to do  but you must first learn how to do it, how to move your hands and how to set your table angles.

Stay with it, seek understanding about how the various angles work and you'll be way ahead. Carbide tools work great but when it comes to tailoring a tool to your specific needs you cannot beat HSS.


----------



## Strtspdlx

mikey said:


> Joe, keep in mind that you are grinding the relief angles at the same time as you are grinding the shape of the tool. That is, when you grind the side cutting edge angle you are also cutting the side relief angle at the same time. When you grind the end cutting edge angle you are cutting the end relief at the same time. The relief angles are set by the angle of your tool rest. If you choose to free hand the tool then your angles will be approximate at best. Your lathe has enough power for a general angle to work but for those guys with small lathes this is going to be a crap shoot. It is better to have a tool rest/table  that can be set to a precise angle and locked down.
> 
> As I said, I agree with using mild steel keystock to learn to grind tools. You are trying to understand how all the angles on a tool are cut. Relief angles are cut as above, while rake angles simply involve a straight push into the wheel or belt; it is much easier and more accurate to do this when you have a tool rest that can be locked at accurate angles. Once you understand how the various angles are cut then you need to learn how those angles function and how they affect cutting forces so that you can alter them to suit your needs. For example, if you need a fine finisher then you can increase side relief to provide a sharper interface and better clearance at the cutting edge and increase back rake to focus the cutting forces at the tip of the tool. Then you can use a slightly larger nose radius to create a really fine finish. None of this is difficult to do  but you must first learn how to do it, how to move your hands and how to set your table angles.
> 
> Stay with it, seek understanding about how the various angles work and you'll be way ahead. Carbide tools work great but when it comes to tailoring a tool to your specific needs you cannot beat HSS.



Not to hi jack this thread and make it about grinding HSS tooling. But... You're making me feel like I need to learn a lot more about how tool geometry effects the loads on a machine. I have a little atlas 10". I work with what I have though which is a little ryobi bench grinder with an aluminum oxide wheel I believe it's 60. And then I just hone the cutter to death.  


Regards-Carlo


----------



## Charles Spencer

I learned to grind lathe tools and drill bits free hand years ago.  It works well, but I came up with something a bit simpler recently.  I bought a Harbor Freight Mini Tool Grinder off a guy cheap ($10).  I sanded off the tool rest, put Dykem on it, and laid out lines at 59 and 30 degrees from both sides.  The beauty of this little thing is that you can position it exactly as you want and it's not intimidating at all.  I plan on getting another wheel for the other side, cutting down a protractor, and affixing it to the base.  You can buy one new for less than $25 if you use a 20% off coupon.


----------



## Bill C.

Strtspdlx said:


> Well here's a picture of
> My most commonly used tool. As I had said before I watched some videos and measured some angles sometimes and I never got the results I desired. My tools may not be correct or at an exact angle but they work for my purposes. The first picture of bar is a piece of unknown ss I turned the next is mild steel. Hopefully this helps if not let me know and I'll try to answer to the best of my knowledge.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> View attachment 107038
> View attachment 107039
> View attachment 107040
> View attachment 107041
> View attachment 107042
> View attachment 107043
> View attachment 107044
> View attachment 107045
> View attachment 107046
> 
> 
> 
> Regards-Carlo



Good looking bit you are holding.  Thanks for sharing.


----------



## Bill C.

Charles Spencer said:


> I learned to grind lathe tools and drill bits free hand years ago.  It works well, but I came up with something a bit simpler recently.  I bought a Harbor Freight Mini Tool Grinder off a guy cheap ($10).  I sanded off the tool rest, put Dykem on it, and laid out lines at 59 and 30 degrees from both sides.  The beauty of this little thing is that you can position it exactly as you want and it's not intimidating at all.  I plan on getting another wheel for the other side, cutting down a protractor, and affixing it to the base.  You can buy one new for less than $25 if you use a 20% off coupon.
> View attachment 107083



You could use a small piece of flat stock and a vise-grip to clamp it making a temporary guide using your lines if you are grinding several bits.


----------



## Joe Pitz

Hey Charles, what is the thin wheel on the left, is that a cutting wheel or a diamond wheel.

I like the dykem on the rest idea.  looks good.

Joe


----------



## Charles Spencer

It's a regular cutting wheel.  All I've used it for is to sort of notch round stock that I'm going to cut on my vertical bandsaw.  It helps getting started.


----------



## Joe Pitz

thanks Charles,  good idea


----------



## benmychree

JimDawson said:


> Free hand grinding just take little practice, keep in mind the tip and the left side of the tool ( for a right hand tool) is doing all of the work, everything else is just clearance.  The angles are not critical.  If the tool grind does not produce the desired result, then try again with slightly different angles.
> 
> While I do have a tool grinder with green wheels, I normally just use my cheap Chinese bench grinder with with a standard aluminum oxide gray wheel.  You just have to push a little harder.  On the other hand, I do a lot of things that aren't ''normal''  IMHO, as long as shop safety practices are observed, anything goes in machining.  There is no ''right way'' to do an operation as long as the part comes out the way you want it to.
> .
> .


There is an alternative to the green grit grinding wheels for carbide grinding; the shop that I apprenticed in did not have diamond wheels, at least that were available on the shop floor, instead, they used a grey colored straight type wheel in a bench grinder.  In practice, one would undermine the carbide if a lot of carbide needed to be ground back, and then use the grey wheel to finish the job.  These wheels were not the typical light grey of aluminum oxide, but a dark charcoal grey, and I presume they must have been silicon carbide.  The tendency to chip the carbide was much less than with green grit wheels that I have typically seen, although perhaps the fact that most seem to be overly coarse grit may make a difference also.  The wheel specification follows:
Radiac
A.P. De Sanno & Sons
C 100 - H02 - VD2
The size we used was 7 x 1 x 5/8


----------



## Joe Pitz

Thanks bennychree for the info on silicon carbide wheels.

Joe


----------



## mikey

Carlo,


Strtspdlx said:


> Not to hi jack this thread and make it about grinding HSS tooling. But... You're making me feel like I need to learn a lot more about how tool geometry effects the loads on a machine. I have a little atlas 10". I work with what I have though which is a little ryobi bench grinder with an aluminum oxide wheel I believe it's 60. And then I just hone the cutter to death.
> Regards-Carlo



Carlo, I think its great that you've experimented with various tool shapes and angles but I do wonder if you realize how much potential you have at your disposal. I have not worked with an Atlas 10 but my understanding is that these are not the most rigid lathes in the world. Accordingly, it would be good to know how to reduce cutting forces by changing the various tool angles. For example, just a few more degrees of side relief and side rake will significantly reduce cutting forces and allow a tool that would previously chatter to cut smoothly and more accurately. Cutting force reduction isn't only for roughing. A tool that cuts with less forces will also size more accurately and finish better so it is worth the time to learn how shape and alter tools to suit your needs.

The roughing tool I showed above can easily take a 0.030" depth of cut in mild steel on my little Sherline lathe. A similar tool with modified relief, side/back rake can take an 0.050" deep cut with less strain on the lathe with a far better finish. That same tool will shave off 0.001" off an OD, too. And it won't chatter. 

My point is that you can tailor the tool to your needs but you have to know how to grind it and modify it so it does what you want it to do - predictably.


----------



## JR49

mikey said:


> The roughing tool I showed above can easily take a 0.030" depth of cut in mild steel on my little Sherline lathe



Mikey,  How about a Tutorial on the different degrees of the  angles used , and for what purposes. I posted on the first page that I felt I was pretty good at tool grinding, BUT, after reading your posts, I'm not so sure anymore. I'm sure Carlo, and myself, and Joe, would like to learn more.  Thanks,  JR49


----------



## Joe Pitz

JR49 and all,

mikey sent me some articles that he wrote on the proper way for new guys like us to grind lathe tooling.

http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander/
http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-2/
http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-3/#more-5897

I am currently reading them and they are great.  Clears up many questions I have on proper tool geometry.

Thanks

Joe


----------



## mikey

JR49 said:


> Mikey,  How about a Tutorial on the different degrees of the  angles used , and for what purposes. I posted on the first page that I felt I was pretty good at tool grinding, BUT, after reading your posts, I'm not so sure anymore. I'm sure Carlo, and myself, and Joe, would like to learn more.  Thanks,  JR49



I wrote those articles that Joe linked to some years ago to answer questions just like those we're discussing here. A guy on a forum was totally lost and couldn't wrap his head around how tool geometry worked so I wrote that just for him and then later polished it up for Rob, the owner of Machinistblog.

Its one thing to watch a video and see how a tool can be ground but it is quite another thing to understand how the angles actually work and then altering them to suit your purposes. Those articles will hopefully give you an idea of how to make your tools do what you want them to do. Have a look and we can discuss this more if you feel the need.

Oh, I should add that that article was for small lathe users because that is what the guy had - a Sherline lathe. The same principles apply to larger lathes as well. I can take a tool and grind it to reduce cutting forces on my 11" Emco lathe just as easily and it will cut far better than a tool with standard tip geometry.


----------



## mikey

Guys, I've been thinking about our discussions and it seems to me that some of you are capable tool grinders. If that is the case then don't think you have to change what you're doing. On the other hand, for those of you who have smaller lathes that seem to struggle a bit then I suggest to you that you can grind a tool that will work far better than a standard geometry tool. The angles found in the typical angle table are suggestions based on what is known to work on larger lathes in production situations but if your lathe is not one of those larger lathes then using those angles may produce cutting forces that can cause problems for you. Every tool angle has a purpose and while not all of them need to be modified, when we do change them for the right reasons the difference in performance can be significant.

I know of one guy who does not use back rake on his tools; his videos show this. That's okay but you must also realize that back rake plays an important role in chip clearance, force focalization, cutting forces and cutting temperatures. Not incorporating back rake into your tool may be deleterious to your tools performance.

If you read the articles Joe linked to above you might have the impression that these angle changes only apply to little lathes and don't have a place on larger lathes but you would be wrong. Anytime we can make a tool cut more efficiently with less load and with greater precision then it is worthwhile considering it. The tools I use on my 11" lathe to cut 1144, 4140 and 303 all use larger relief angles, more back and side rake in order to reduce cutting temperatures and allow less cutting forces during the cut. These tools produce cleaner cuts with less work hardening and greater precision. It takes only a few minutes for me to modify a tool to do this and I can tell you that they work far, far better than standard geometry tooling.

I think we get locked into thinking that the table angles are locked in stone but they are simply baseline values. Where we take them from there is up to us and I encourage you to experiment with them. Once you see how much better a modified tool cuts you'll never go back to a standard tool.


----------



## JimDawson

:+1:  What mikey said


----------



## JR49

I would be very interested in hearing what everyone (but particularly Jim and Mikey) think about this statement;   The sharper you make the cutting edge, by increasing rake and clearance angles, the better, more precise, smother, and with less cutting force, the tool will cut.  HOWEVER, increasing the angles too much, will cause the tool to wear faster, so one must find a happy medium between excellent cutting features, and  tool life, or time between sharpening..   What say you guys,  JR49


----------



## francist

Those are really nicely written articles, mikey. Well done!

-frank


----------



## mikey

JR49 said:


> I would be very interested in hearing what everyone (but particularly Jim and Mikey) think about this statement;   The sharper you make the cutting edge, by increasing rake and clearance angles, the better, more precise, smother, and with less cutting force, the tool will cut.  HOWEVER, increasing the angles too much, will cause the tool to wear faster, so one must find a happy medium between excellent cutting features, and  tool life, or time between sharpening..   What say you guys,  JR49



You are correct in concept, JR. The way I approach angle changes is to consider what it is I want to change and why I think I need to change it. You can reduce cutting forces by altering relief angles, side rake and back rake and you can also alter the degree to which you make those changes.

For example, say I am cutting 303 and I want to get the heat out of the cut as fast as I can. In that case I would increase my relief angle a few degrees to gain a sharper interface and increase side rake up to 4-5 degrees to really clear those chips fast. Since I do not necessarily wish to focus my cutting forces at the tip of the tool but prefer to take the load on the side cutting edge I would leave back rake at the standard setting. What this does is give me a sharper cutting edge with better chip clearance and I doubt you would see a breakdown of the cutting edge unless you have a very long production run. I may also increase the end cutting edge relief to improve shearing action at the cut, which can have an impact on work hardening also.

Or say I needed to cut some 1018 (I hate that stuff). I would increase side relief by about 4-5 degrees for better shearing action but keep side rake at baseline for strength. I would increase back rake 3-4 degrees to focus cutting forces near the tip and use a slightly larger nose radius to give me as clean a finish as possible. All of this allows the tool to cut as clean as possible in the lousy material with as good a finish as a tool can give.

I guess my point is that you should use the various angles to give you the advantage you need when and where you need it. You may need to touch up the tool more often but in my hobby shop that hasn't been an issue. I sharpen all my tools after each use or before critical cuts anyway.

*EDIT: I meant to mention that increasing side and back rake will actually improve cutter life while reducing cutting forces and reducing cutting temperatures provided you don't take these angles to extremes. If you wish to have a sharper cutting edge without sacrificing edge strength, leave the relief angles alone and boost side rake - it gives you a sharper interface and better chip clearance without your edge dulling prematurely. Try it - it works.*


----------



## mikey

francist said:


> Those are really nicely written articles, mikey. Well done!
> 
> -frank



Thank you, Frank. I hope they help.


----------



## mikey

Hey JR49, I have a proposition for you. Why not grind what I call a "square tool" and tell us how you think it works in comparison to what you normally use. Pick a general shape that you prefer and grind it with 15 degrees of side and end relief, 15 degrees of side rake, 15 degrees of back rake and put a 1/32" nose radius on it. This tool will cut with very low cutting forces and will enable you to hold tight tolerances. Give it a try and report back.


----------



## Strtspdlx

Not to stick my nose in although I do love to learn. My entire strategy behind grinding tools is to have the cutting edge present itself with the least amount of force necessary. I try to use smaller nose radi in hopes the heat will stay in the work vs being absorbed into the tool and I try to adjust for proper chip clearance but I haven't quite figure that one out yet. So far the only time I've damaged a tool is when I'm not paying attention and touch off way to hard. Or I think I touch off and I don't and run the tool way to deep. My whole outlook has been to present the cutting edge too the tool with enough clearance to keep heat in the work and not the tool. 


Regards-Carlo


----------



## JR49

mikey said:


> Hey JR49, I have a proposition for you.



Will do, Mikey, but it may take a day or two (medical issues, old man stuff)


----------



## mikey

JR49 said:


> Will do, Mikey, but it may take a day or two (medical issues, old man stuff)



Made me laugh. I just had major back surgery 5 days ago and I've been typing these responses while doped up on Hydrocodone. If I offended anyone I sincerely apologize. 

I don't mean to put you in an uncomfortable position, JR. You don't need to make the tool but if you do I suspect you will be surprised that geometry well beyond what we normally use can work well. I would be very interested in what you think.


----------



## mikey

Strtspdlx said:


> Not to stick my nose in although I do love to learn. My entire strategy behind grinding tools is to have the cutting edge present itself with the least amount of force necessary. I try to use smaller nose radi in hopes the heat will stay in the work vs being absorbed into the tool and I try to adjust for proper chip clearance but I haven't quite figure that one out yet. So far the only time I've damaged a tool is when I'm not paying attention and touch off way to hard. Or I think I touch off and I don't and run the tool way to deep. My whole outlook has been to present the cutting edge too the tool with enough clearance to keep heat in the work and not the tool.
> 
> 
> Regards-Carlo



Carlo, most of the heat in a cutting operation is carried off by the chips so chip clearance is very important. Chip clearance is enhanced by side rake - the more side rake you have the better the chip clearance will be. Back rake also plays a role here but not as much as side rake.

In your pictures of your tools you posted earlier in this thread it looks like you use very little side rake and almost no back rake. This will cause your tool to cut with very high cutting forces and poor chip clearance because you are basically presenting a square edge to the work. I would suggest you grind in both side rake and back rake in amounts appropriate for the materials you are cutting. This will give you a much sharper cutting edge that will not only cut cleaner but last longer. It will also clear chips much better and keep cutting temperatures down.

You also said you free hand your tools and never measure angles. That's fine - lots of guys do this. I can free hand a tool and come within a degree or two of what I want but I've been doing it for over 25 years. For best results or until you have a lot of experience I highly recommend you use a rest that you can set at known angles so you can control your geometry. Then take the time to learn to grind the proper relief angles, side and back rake and the tool shapes you require. 

Please don't take this the wrong way as I'm not trying to criticize you in any way. I want you to succeed and I assure you that there is a great deal to be gained from learning to grind a good tool. Those three articles that Joe linked to above will give you a good start in understanding how all the angles work and how they can be ground into your tools. 

Joe started this thread and it has evolved into a tool grinding thread. That's okay - so far, Jim hasn't put a stop to it and until he does we can all use it to help each other and share what we know about tool grinding. I, for one, value your input.


----------



## JR49

mikey said:


> I don't mean to put you in an uncomfortable position, JR.



Are you kidding?  Threads like this one are my favorites. I hope Joe is OK with how his thread has evolved, cause there is definitely a lot to be learned here.  As far as putting me on the spot, here is what I'm planning.  Just the other day I ground a 3/8" tool with front and side clearance, a small nose radius, but almost no side or back rake. This tool seemed to cut pretty well on my 12" Logan, BUT, I don't really think that I have enough experience to know the difference between a good cutting tool or a poor cutter.  So I'm going to grind another 3/8" tool with the angles that you listed in post #78. Then I will cut  the same steel rod,  half with each tool.  This way even a beginner like me should see a difference, and if it is OK with you Joe, I'll report my findings here.  One thing I need from you first Mikey is, please tell this beginner what you mean by   a "square tool" Thanks,  JR49


----------



## JimDawson

mikey said:


> Joe started this thread and it has evolved into a tool grinding thread. That's okay - so far, Jim hasn't put a stop to it and until he does we can all use it to help each other and share what we know about tool grinding. I, for one, value your input.




I think this thread has a lot of valuable information and even this old dog is learning   The lack of learning how to hand grind tools is one of my pet peeves.  I don't use insert tools and have always hand ground my own, be it carbide or HSS.


----------



## mikey

JR49 said:


> Are you kidding?  Threads like this one are my favorites. I hope Joe is OK with how his thread has evolved, cause there is definitely a lot to be learned here.  As far as putting me on the spot, here is what I'm planning.  Just the other day I ground a 3/8" tool with front and side clearance, a small nose radius, but almost no side or back rake. This tool seemed to cut pretty well on my 12" Logan, BUT, I don't really think that I have enough experience to know the difference between a good cutting tool or a poor cutter.  So I'm going to grind another 3/8" tool with the angles that you listed in post #78. Then I will cut  the same steel rod,  half with each tool.  This way even a beginner like me should see a difference, and if it is OK with you Joe, I'll report my findings here.  One thing I need from you first Mikey is, please tell this beginner what you mean by   a "square tool" Thanks,  JR49



I call it a square tool because all the angles are the same - side relief, end relief, back rake and side rake - all 15 degrees. I've ground *hundreds* of experimental tools and have found this particular combination to cut well in most materials. It is not optimized for any one metal but will do a decent job on most, from mild steel to stainless to 1144 and even aluminum. It is fast to cut because the table angle doesn't change. It is also easy to resharpen for the same reason. On my belt sander I can grind one from a blank in about 4 minutes and hone it for use in another minute. 

Typically, I will shape this tool halfway between a rougher and facing tool so it is a general purpose tool that will turn and face by changing the lead angle. I made one just like this in the third article in the series Joe linked to. Your tool should look very much like that one. I think you will find it cuts well for you and wanted you to see that even on a lathe larger than a little Sherline such a tool can be useful.

Oh, just so you know, I chose you to do this because you said you were an excellent tool grinder and I have no doubt that you are. Once you add this to your collection it will give you a basis to experiment more with angle changes. It usually only takes a few degrees more added to a standard angle to produce a significant impact, especially side rake angles. Anyway, you're the guy right now. When Joe catches up we'll put him on the spot!

We await your report!


----------



## mikey

JimDawson said:


> I think this thread has a lot of valuable information and even this old dog is learning   The lack of learning how to hand grind tools is one of my pet peeves.  I don't use insert tools and have always hand ground my own, be it carbide or HSS.



Thank you, Jim, for your support. I know there are a lot of new guys out there reading this stuff and not saying a single thing. There are also a lot of experienced tool grinders who are just as silent. Jump in, guys!


----------



## Strtspdlx

mikey said:


> Carlo, most of the heat in a cutting operation is carried off by the chips so chip clearance is very important. Chip clearance is enhanced by side rake - the more side rake you have the better the chip clearance will be. Back rake also plays a role here but not as much as side rake.
> 
> In your pictures of your tools you posted earlier in this thread it looks like you use very little side rake and almost no back rake. This will cause your tool to cut with very high cutting forces and poor chip clearance because you are basically presenting a square edge to the work. I would suggest you grind in both side rake and back rake in amounts appropriate for the materials you are cutting. This will give you a much sharper cutting edge that will not only cut cleaner but last longer. It will also clear chips much better and keep cutting temperatures down.
> 
> You also said you free hand your tools and never measure angles. That's fine - lots of guys do this. I can free hand a tool and come within a degree or two of what I want but I've been doing it for over 25 years. For best results or until you have a lot of experience I highly recommend you use a rest that you can set at known angles so you can control your geometry. Then take the time to learn to grind the proper relief angles, side and back rake and the tool shapes you require.
> 
> Please don't take this the wrong way as I'm not trying to criticize you in any way. I want you to succeed and I assure you that there is a great deal to be gained from learning to grind a good tool. Those three articles that Joe linked to above will give you a good start in understanding how all the angles work and how they can be ground into your tools.
> 
> Joe started this thread and it has evolved into a tool grinding thread. That's okay - so far, Jim hasn't put a stop to it and until he does we can all use it to help each other and share what we know about tool grinding. I, for one, value your input.



I'm going to try as you suggested next time I can get out to my shop. I read the linked articles but I have memory issues and it just didn't seem to sink in. Maybe I'll read them several times over and see if any of it soaks in. 
I had never thought of the chips being the place to direct the heat. I'm lad you mentioned it however as it makes more sense then my way. 
Hopefully adjust the angles will achieve better results I use those two tools for just about everything mainly because I'm too lazy to reset everything for a new tool. 


Regards-Carlo


----------



## mikey

Strtspdlx said:


> I'm going to try as you suggested next time I can get out to my shop. I read the linked articles but I have memory issues and it just didn't seem to sink in. Maybe I'll read them several times over and see if any of it soaks in.
> I had never thought of the chips being the place to direct the heat. I'm lad you mentioned it however as it makes more sense then my way.
> Hopefully adjust the angles will achieve better results I use those two tools for just about everything mainly because I'm too lazy to reset everything for a new tool.
> 
> 
> Regards-Carlo



I know you feel otherwise but I really think practicing with mild steel keystock is the best way to learn to grind a tool bit. It cuts easily and allows you to understand how to hold and angle the bit to get the results you need. Once you are comfortable with the procedure then switch to HSS. Grinding tools isn't hard to do but it takes practice to wrap your head around the process. Stick with it, Carlo - it will come.


----------



## Doubleeboy

Someone starting out and struggling with sharpening lathe tools and lathe operations in general might be well served to check out this link.  A motherload of info IMO. 

http://team358.org/files/mechanical/HowToUseALathe.pdf

cheers
michael


----------



## francist

Ok, jumping in....

For starters I'm not especially new to the mechanics of tool grinding, but I am less versed with the performance aspects of various grinds so I've been following this discussion quite closely. I think for me, the most salient take-away has been that while the textbook numbers may be tried and true based on much research, those numbers may not be the best option for smaller machines that typically don't take huge cuts or do long production runs. It's a basic factor for me, a smaller lathe user to consider, and I'm almost embarrased I hadn't taken it to my tool grinding as well.

With that said, and the coincidental arrival of five fresh tool blanks last week, I ground one of mikey's "square tools" last night. I ground it as more of a roughing shape though, and in keeping with the theme made the lead angle 15-degrees as well. Then I honed it as I always do, stuck it in my little Atlas, and fed it some 6061.

Very nice, I'm liking it! Easy-breezy cutting, nice finish, decent chip direction. I can't give a percentage-point advantage compared to what I was using before, but it just *felt* better. Where I may have backed off my DOC before, that threshold has moved further out with the new tool. And to my mind, that's improvement.

So, I can't wait to try another one. I do use my grinder though instead of the belt machine. It works for me and I made an adjustable rest that is easy to adjust and holds the angles well so I'm sticking with it. 

Great discussion, guys. Very useful indeed and some really good banter.

-frank


----------



## Joe Pitz

JR49 said:


> Are you kidding?  Threads like this one are my favorites. I hope Joe is OK with how his thread has evolved, cause there is definitely a lot to be learned here.  As far as putting me on the spot, here is what I'm planning.  Just the other day I ground a 3/8" tool with front and side clearance, a small nose radius, but almost no side or back rake. This tool seemed to cut pretty well on my 12" Logan, BUT, I don't really think that I have enough experience to know the difference between a good cutting tool or a poor cutter.  So I'm going to grind another 3/8" tool with the angles that you listed in post #78. Then I will cut  the same steel rod,  half with each tool.  This way even a beginner like me should see a difference, and if it is OK with you Joe, I'll report my findings here.  One thing I need from you first Mikey is, please tell this beginner what you mean by   a "square tool" Thanks,  JR49



JR, I do not mind at all, mikey has been helping me and providing me good info.  I love all of the different views and perspectives given,  I love how this post has progressed.  and welcome everyone's feedback and experimentation's.  I am learning a bunch.

Joe


----------



## mikey

francist said:


> Ok, jumping in....
> 
> For starters I'm not especially new to the mechanics of tool grinding, but I am less versed with the performance aspects of various grinds so I've been following this discussion quite closely. I think for me, the most salient take-away has been that while the textbook numbers may be tried and true based on much research, those numbers may not be the best option for smaller machines that typically don't take huge cuts or do long production runs. It's a basic factor for me, a smaller lathe user to consider, and I'm almost embarrased I hadn't taken it to my tool grinding as well.
> 
> With that said, and the coincidental arrival of five fresh tool blanks last week, I ground one of mikey's "square tools" last night. I ground it as more of a roughing shape though, and in keeping with the theme made the lead angle 15-degrees as well. Then I honed it as I always do, stuck it in my little Atlas, and fed it some 6061.
> 
> Very nice, I'm liking it! Easy-breezy cutting, nice finish, decent chip direction. I can't give a percentage-point advantage compared to what I was using before, but it just *felt* better. Where I may have backed off my DOC before, that threshold has moved further out with the new tool. And to my mind, that's improvement.
> 
> So, I can't wait to try another one. I do use my grinder though instead of the belt machine. It works for me and I made an adjustable rest that is easy to adjust and holds the angles well so I'm sticking with it.
> 
> Great discussion, guys. Very useful indeed and some really good banter.
> 
> -frank



Outstanding, Frank! I'm glad the tool seems to work well for you but am even happier that you know how to alter your tool geometry to better suit your smaller lathe. I couldn't have hoped for a better outcome - congratulations!

Keep us posted on your future efforts and if there is anything I can do to assist you, please let me know.

Mikey


----------



## Tozguy

mikey said:


> I know you feel otherwise but I really think practicing with mild steel keystock is the best way to learn to grind a tool bit. It cuts easily and allows you to understand how to hold and angle the bit to get the results you need. Once you are comfortable with the procedure then switch to HSS. Grinding tools isn't hard to do but it takes practice to wrap your head around the process. Stick with it, Carlo - it will come.


 
This reflects my experience very well. It was only after getting equipped properly to grind lathe tools that it became comfortable for me. As in many other operations the right equipment is a prerequisite. Now that it is fun for me to grind, I don't hesitate to tailor angles for a specific job and keep tools sharp. It all translated into more enjoyment in using the lathe.


----------



## Strtspdlx

Mikey 
Instead of quoting and wasting space for valuable information I'm hoping I can just reference your last post and there won't be confusion. So I'm going to try. 
As far as mild steel blanks I only really dislike the idea because when I started I went around and bought up every piece of tooling I could get my hands on. Needless to say for less then $100 I must have well over 200 blank hss bits in various sizes. So I'm not necessarily opposed to your idea. I just don't wish to spend the money. I do firmly believe if I want to get a specific angle in any place on a tool it can be done. I do have adjustable tables and protractors and misc measuring tools for angles I just chose to never use them. Hopefully today I'll get out to my shop. I'd like to measure the current angles of my tools and adjust them to your guidelines and see what I get. Please keep the help coming if there's a better way id love to know it. 


Regards-Carlo


----------



## mikey

Strtspdlx said:


> Mikey
> Instead of quoting and wasting space for valuable information I'm hoping I can just reference your last post and there won't be confusion. So I'm going to try.
> As far as mild steel blanks I only really dislike the idea because when I started I went around and bought up every piece of tooling I could get my hands on. Needless to say for less then $100 I must have well over 200 blank hss bits in various sizes. So I'm not necessarily opposed to your idea. I just don't wish to spend the money. I do firmly believe if I want to get a specific angle in any place on a tool it can be done. I do have adjustable tables and protractors and misc measuring tools for angles I just chose to never use them. Hopefully today I'll get out to my shop. I'd like to measure the current angles of my tools and adjust them to your guidelines and see what I get. Please keep the help coming if there's a better way id love to know it.
> 
> 
> Regards-Carlo



Carlo, ANYTHING you have to say has value as far as I am concerned. I also understand and accept that since you have a wealth of HSS blanks around, and the means to grind angles into them accurately then that would be your preferred route - go for it. What really matters is that you understand how to grind all the relief and rake angles the way you want them to be. I have no doubt that you'll figure it out but if something isn't making sense, we are here.

Mikey


----------



## Strtspdlx

I need to engrave the terminology in my head. Every time you refer to an angle I have to go in my book and look at exactly what you're talking about. Like you've already
Mentioned time and experience are the major things to figuring out how to do it correctly. 


Regards-Carlo


----------



## JR49

Boy, this thread has really taken off.  Still planning to test out mikey's angles , but presesnly i'm reading this in the surgery waiting room. (Wife is having a minor procedure), but hope to get to it this weekend.  JR49


----------



## mikey

JR49 said:


> Boy, this thread has really taken off.  Still planning to test out mikey's angles , but presesnly i'm reading this in the surgery waiting room. (Wife is having a minor procedure), but hope to get to it this weekend.  JR49



First things first, JR. Hope all goes smoothly.


----------



## Strtspdlx

Alright guys I didn't quite measure my tooling. I tried but I don't trust my measuring tools. So I went ahead and tried threading with a hand ground 60* tool. I figured since we where on the subject of hss tooling I'd post a picture of the rough threads. These where not meant for any purpose other then to see if I could thread anything on my lathe with any success whatsoever. The material is unknown SS. I should've got a picture of the tool but I was in a bit of a hurry. So here's what I ended up with. Questions now.
When I get to a certain depth it is showing chatter
Marks along the length of the thread but I can't hear or feel any when cutting. What may cause that? Should I have back rake on a threading tool? My holder is already angled 15* up I believe. 
	

		
			
		

		
	





Regards-Carlo


----------



## JimDawson

Carlo, I see a couple of things.  Your work was not supported by the tailstock so I'm surprised that it didn't chatter even more, that is a lot of stick out.  Normally about 3x the diameter of the work is the max.  This would indicate that your tool is working just fine.

When threading, as the tool goes deeper, the cut is wider, so more prone to chatter.  Run another piece, and support the end with the tailstock center and I'll bet the chatter goes away.


----------



## Strtspdlx

JimDawson said:


> Carlo, I see a couple of things.  Your work was not supported by the tailstock so I'm surprised that it didn't chatter even more, that is a lot of stick out.  Normally about 3x the diameter of the work is the max.  This would indicate that your tool is working just fine.
> 
> When threading, as the tool goes deeper, the cut is wider, so more prone to chatter.  Run another piece, and support the end with the tailstock center and I'll bet the chatter goes away.



In all honesty I had figured as much being unsupported. And the tool height wasn't right and and and.  I just jumped into it and started playing. When I had made my scratch pass I had it kind of supported then I decided to
Move the tail stock because it was interfering with my movements. It's just odd I'm so used to hearing or feeling chatter. This just cut a nice curly chip with no noise whatsoever. 


Regards-Carlo


----------



## Joe Pitz

Hello All, I picked up a HF belt sander, normally $79.00, Item #69033, used a 20% discount coupon.  Using mikey's articles 
I have been practicing my tool grinding.

Here are some shots of my second attempt.  A little more positive rake angle on the top and I should have it down.

I am using the general purpose grind in article 3 as a learning example.

I can say using the tool rest makes it much easier to repeat the compound angles.  

I am really enjoying the learning experience.

Thanks

Joe


----------



## JimDawson

Looks like a tool bit to me!


----------



## Joe Pitz

Thanks Jim for the positive feedback

Joe


----------



## mikey

Yup, looks like one to me, too! Good job, Joe!


----------



## higgite

Good job, Joe. You're finding out what I found out... hang around here long enough and some good stuff starts to rub off on you.

Tom


----------



## Joe Pitz

Thanks Tom,  Yes, that is what I am finding out. 

Joe


----------



## JR49

It's great to here that you're getting the hang of grinding, Joe.  I'm sure most think that I've abandoned  my test of mikey's angles by now, but actually, I've been dealing with some health issues.  I hope to report my results soon.  Happy machining,  JR49


----------



## Joe Pitz

JR get better, we need you out in the shop.  " I feel a weakness in the force"

Joe


----------



## mikey

Joe Pitz said:


> JR get better, we need you out in the shop.  " I feel a weakness in the force"
> 
> Joe


 +1, JR.


----------



## mikey

This is going to sound really stupid but when I first started grinding tools I wondered how long each face of the tool "should" be. There isn't a formula for this but over the years I have settled on making the side cutting edge 1-1/2 to 2 times the height of the tool (so, for a 3/8" square tool bit the side cutting edge should be 9/16 to 3/4" long).  The end cutting edge ends up whatever it is depending on tool shape. For the top rake, 1 to 1-1/2 times the size of the bit works well. This is the length from the tip of the tool to the end of the side rake angle.

When grinding a roughing tool, if you angle the tool so that you make the side cutting edge to the above length while also taking off about 40% of it's width at the end, the tool shape works well. For a facing tool take off 70% and for a finisher take off 80%. For a general purpose tool, take off about 60%. These are approximations but work well for me.
*EDIT: *I should make it clear that the reason for the amounts taken off as above is to provide the lead angle required by these different tools to work properly when the tool shank is perpendicular to the work. If you look at the books the lead angle is actually a bit less than I use but I have found these shapes to work better for me. I just want to be clear that this is MY practice; do what you think is best.

Here's one that never made sense to me. A rougher cuts primarily with the tip and side cutting edge, while a facer cuts mainly with the side cutting edge near the tip and a finisher cuts primarily with the nose radius of the tool. Each tool is meant to take the load in different areas to perform different functions. Why, then, do all the angles in the typical angle table remain the same for all of these tools for a given material? I don't know why but it makes sense to me that the angles should change to suit the purpose of the tool ... so I change 'em and it has made all the difference!


----------



## Strtspdlx

Joe, 
You made yourself a very nice looking tool!!!   Now let's see how she cuts!!!


Regards-Carlo


----------



## Joe Pitz

Thanks Carlo, that is the next step.

I will include some pics when I do.

Joe


----------



## JR49

My apologies to all, for never getting back to this post with the results of the test that I promissed to do. I first thought that my "old man" health issues would only delay my report a week or so, but now, further tests on a completely unrelated issue have determined that I quickly start 9 weeks of radiation treatments, and by then, this post will be long forgotten. I was able to find enough time in the shop to grind a tool using mikey's angles, and have to say that it cut very well and left a very good finish. Mikey also posted a great response yesterday, to a thread by Pinresto "Lathe noob with some questions on first cuts". Reading that thread is what motivated me to make this post, as we are all lucky to have such giving members like Mikey and Jim Dawson, as well as many others. PLEASE NOTE; this post is intended to give mikey's tool grinding technique the credit it deserves, and to show why I didn't do as I promised. No sympathy posts are needed or wanted, as I will be back to making chips by October or sooner, and will still be on my favorite forum until then. Happy machining to all, JR49


----------



## Joe Pitz

JR, it looks like it is time to catch up on all those machining articles you been wanting to read.

Joe


----------



## mikey

JR49 said:


> My apologies to all, for never getting back to this post with the results of the test that I promissed to do. I first thought that my "old man" health issues would only delay my report a week or so, but now, further tests on a completely unrelated issue have determined that I quickly start 9 weeks of radiation treatments, and by then, this post will be long forgotten. I was able to find enough time in the shop to grind a tool using mikey's angles, and have to say that it cut very well and left a very good finish. Mikey also posted a great response yesterday, to a thread by Pinresto "Lathe noob with some questions on first cuts". Reading that thread is what motivated me to make this post, as we are all lucky to have such giving members like Mikey and Jim Dawson, as well as many others. PLEASE NOTE; this post is intended to give mikey's tool grinding technique the credit it deserves, and to show why I didn't do as I promised. No sympathy posts are needed or wanted, as I will be back to making chips by October or sooner, and will still be on my favorite forum until then. Happy machining to all, JR49



JR, the most important thing in life is life itself. This forum, tool grinding posts or whatever else we do here have no importance when compared to what you're dealing with. You are in my thoughts and I will pray for your speedy recovery. Come back to us when you can - we'll be here.

Oh, and thanks for the kudos but I'm sure there are many others who would have posted the same stuff if I didn't get there first.


----------



## Doubleeboy

mikey said:


> This is going to sound really stupid but when I first started grinding tools I wondered how long each face of the tool "should" be. There isn't a formula for this but over the years I have settled on making the side cutting edge 1-1/2 to 2 times the height of the tool (so, for a 3/8" square tool bit the side cutting edge should be 9/16 to 3/4" long).  The end cutting edge ends up whatever it is depending on tool shape. For the top rake, 1 to 1-1/2 times the size of the bit works well. This is the length from the tip of the tool to the end of the side rake angle.
> 
> When grinding a roughing tool, if you angle the tool so that you make the side cutting edge to the above length while also taking off about 40% of it's width at the end, the tool shape works well. For a facing tool take off 70% and for a finisher take off 80%. For a general purpose tool, take off about 60%. These are approximations but work well for me.
> *EDIT: *I should make it clear that the reason for the amounts taken off as above is to provide the lead angle required by these different tools to work properly when the tool shank is perpendicular to the work. If you look at the books the lead angle is actually a bit less than I use but I have found these shapes to work better for me. I just want to be clear that this is MY practice; do what you think is best.



Mikey, any chance you have photos of your 3 bits, roughing, facing and finishing, that might be helpful.  I for one would be interested in seeing them.

cheers
michael


----------



## mikey

Got the bits but the camera is on its way to China with a friend. Can I please ask for some time?


----------



## Doubleeboy

No problem Mikey, its great that you will be able to do that, should help a lot of folks.  Even though I have been at this off and on for decades I still learn by seeing others tools and work.

cheers
michael


----------



## mattthemuppet2

Joe Pitz said:


> Hello All, I picked up a HF belt sander, normally $79.00, Item #69033, used a 20% discount coupon.  Using mikey's articles
> I have been practicing my tool grinding.
> 
> Here are some shots of my second attempt.  A little more positive rake angle on the top and I should have it down.
> 
> I am using the general purpose grind in article 3 as a learning example.
> 
> I can say using the tool rest makes it much easier to repeat the compound angles.
> 
> I am really enjoying the learning experience.
> 
> Thanks
> 
> Joe



Looks good Joe. The next thing to do is get a medium and a hard Arkansas stone (or medium and fine diamond hones) and hone that cutting edge. It'll make a world of difference. At the same time, you can stone a small radius onto that tip so that a) it leaves a smoother finish and b) it holds up longer.

Certainly looks better than my first attempt


----------



## Joe Pitz

Thanks Matt,  Yes, a good stone is on my list.


----------



## mattthemuppet2

You're welcome  I got a rather chintzy little wooden thing with two 2 x 3 stones (medium and hard) and a holder with a bottle of honing fluid in between for $13 or so off eBay. Looks cheesy but it's been heavily used and it's very easy to do both the rough and finish hones as they're right next to each other.


----------



## Joe Pitz

Yes Matt, I have been looking at something very similar.

Joe


----------



## mikey

Doubleeboy said:


> No problem Mikey, its great that you will be able to do that, should help a lot of folks.  Even though I have been at this off and on for decades I still learn by seeing others tools and work.
> 
> cheers
> michael



It will be a month before I get that camera back and I hope there is still interest in it, Mike.


----------



## Joe Pitz

mikey there will always be interest in looking at professional ground tooling.

Joe


----------



## mattthemuppet2

something like this, even think that this was the store I got mine from!
http://www.ebay.com/itm/Sharpeners-...s-Oak-Mount-/381344208177?hash=item58c9e2d531

in fact, after looking through the store, this is _exactly_ what I got and it's only $11. Still have over 1/2 the bottle left too after a couple of years.
http://www.ebay.com/itm/Sharpeners-...-Honing-Oil-/381347010142?hash=item58ca0d965e


----------



## Joe Pitz

Thanks Matt for the ebay links.

Joe


----------



## mikey

Joe Pitz said:


> mikey there will always be interest in looking at professional ground tooling.



I'm merely competent at best, Joe, but not a pro by any stretch of the imagination. 

I've been thinking about this and wonder what it is you guys really need to see. I hope Mike (Doubleeboy) is reading this. I can certainly show you pics of my used tools when I get my camera back but I'm not sure of the value in that. I'll tell you why.

I have over 20 years on a Sherline lathe and have had to learn how to modify tools to expand on that lathe's already decent capabilities. Up to about 5 years ago I only used dedicated tool sets (rougher, finisher) and a Knife Tool for facing for everything I did. I had a set for every common material I worked with. However, I have changed my preference to a general tool shape because it is stronger, performs as well as dedicated tools when used with the proper lead angle and it is easier for me to maintain one tool instead of two or three. I now use a general tool for most things except facing and thin work finishing; I use the Knife Tool for that but the general tool faces nearly as well. I have a general tool for each commonly used class of material I work with because the tool angles change with the material. Even though I have a larger lathe now but I still prefer these tools.

Now that we have QCTP and can alter lead angle almost instantly, I really wonder if very many of us use a tool perpendicular to the work anymore. If not then the older tool shapes are not going to be of much interest. This thread has over 3800 views so something is of interest. I'm just not sure what that is, exactly. If folks need more detail on tool mods, I can provide my understanding on that. If its on how to actually grind the tool then we can do that, too, and provide pics and a narrative. It sort of depends on what folks need or want and that I don't know. 

Mike, if I was to provide a pic on a good general lathe tool instead of the more archaic shapes would that be of greater interest? What do you think?


----------



## Doubleeboy

Mike, I think I am kind of like you, not a pro full time, but have been around the block a few times.  Turned a ring on a Rockwell lathe in 8th grade shop class almost 50 years ago and have never regretted time spent in front of a machine, even when paid a pittance.  I always look forward to finding pre ground used HSS tools at swap meets and metal working shows, just to see profiles that I have not seen before or used.   As rudimentary as they may be any photos of tools that are of use on low hp machines or other wise are a gift as far as I am concerned.

It is just recently that I have been fooling around with HSS negative rake tooling and am finding that when sharp as a razor and presented at appropriate lead angle it will cut like a hot knife thru butter, yet all these years I have been believing the tale that only positive rake with big reliefs will work with low hp machines.  For me its all about learning, I do this for fun, so yes I would welcome seeing photos of your go to tools even if its a year from now.

Kind Regards
michael


----------



## mikey

Thank you, Mike - glad you were watching. Unlike you, I'm no pro; just a hobby guy like many of us here. I will try to borrow a camera so we don't stall this thread waiting on me. I'll take a shot of an oft-used and very functional general use tool for steel. It is probably used more than most of my tools and is representative of the group. It is also very functional on my Sherline and my 11" Emco. While I'm not sure how it will help anyone, I will take some pics of it as soon as I can, okay? Thank you for getting back to me, Mike.

There are so many ways to grind a tool, some good, some not so good. I have about 15 pounds of old HSS tools ground by professional machinists and its amazing that so many shapes can be ground into a blank. Most of them are crude but they get the job done. Sadly, modern tools are rapidly replacing those old custom-made boring and turning tools and the skills those old guys had is rapidly fading away. If we are to help preserve even a basic knowledge of those skills this is where we will do it - a hobby forum - and I'm honored to play even a small part in that. I am hopeful that other forum members who also grind tools will chip in here so we can all learn more about it. 

Funny you should mention negative rake tooling. I played around with that many years ago and never quite got it right, at least not on my little Sherline. Jim Dawson also told me about using a brazed carbide tool set below centerline and I haven't wrapped my head around that one yet, either. So much to learn and try. I'll keep your comment and Jim's in mind and will mess with it when time allows.

Oh, I emailed Joe Pitz and we discussed what info he would find useful. I figured he is the OP so I need to meet his needs. He has requested more info on how to actually modify lathe tools and I'll work on something I hope the forum finds useful.


----------



## JR49

mikey said:


> Now that we have QCTP and can alter lead angle almost instantly, I really wonder if very many of us use a tool perpendicular to the work anymore.



I can't believe you wrote this Mikey, because, of all your posts/tutorials  I have read (and that's all of them that I have found), the ONLY thing that I did not agree with, (and believe me, as a noob, I figured I was wrong) is when you advised grinding away so much of the front of the tool to create such a large leade angle.  Now I realize this is because I have never, in my limited experience, used anything but a QCTP, and have always been able to select the leade angle I want by simply turning the tool post.  Off course, there are times when  an acute lead angle ground on the tool itself is needed, like when avoiding a crash when turning very close to the chuck. Thanks for the reassurance,  JR49


----------



## mikey

JR49 said:


> I can't believe you wrote this Mikey, because, of all your posts/tutorials  I have read (and that's all of them that I have found), the ONLY thing that I did not agree with, (and believe me, as a noob, I figured I was wrong) is when you advised grinding away so much of the front of the tool to create such a large leade angle.  Now I realize this is because I have never, in my limited experience, used anything but a QCTP, and have always been able to select the leade angle I want by simply turning the tool post.  Off course, there are times when  an acute lead angle ground on the tool itself is needed, like when avoiding a crash when turning very close to the chuck. Thanks for the reassurance,  JR49



Yup, the advent of the QCTP has changed many things and tool shapes and the way they are oriented is no longer a standard. That's fine as long as we recognize that the side cutting edge angles are there for a reason. I can't speak for others but even though I may now use a general purpose shape in a QCTP, the lead angle in use for a given operation is very close to what an old timey tool would be when positioned perpendicular to the work. This isn't just habit.

Machinery's Handbook recommends using as much lead angle as possible [to enhance finishes] as long as there is no chatter. If you take a roughing tool, an old-timey tool or a shop-ground new age general purpose tool, and alter the lead angle until it chattered and then backed off until it cut sweet you will find that the side cutting edge angle will be very close to what the standard side cutting edge angle is. Or at least that was the case when I tested it in my shop ... Hmm.

Things are the way they have been for well over a century for a reason. We may use different tool holding devices and we may shape our tools differently but that doesn't make the reason less valid.


----------



## JR49

Once again, Mikey, your advise is spot on!!  Which is why I enjoy reading your posts. As far as thread topics go, this has been an incredible one. In fact Joe Pitz has started a number of threads that go on a long time, and produced lots of valuable information.  Why are Joe's threads so popular?  Because he's not afraid to admit he is a noob.  So, too all the beginners on this forum, myself included, Lets man up and ask all the basic questions that we've been wondering about, but didn't want to admit we didn't know.  I bet the most basic questions will yield the most watched threads, and remember,  all the "pros" (as I call them) enjoy answering our questions. If they didn't, they wouldn't be here.  Happy Machining, and a BIG THANK YOU to all the "pros",   JR49


----------



## mikey

Doubleeboy said:


> Mike, I think I am kind of like you, not a pro full time, but have been around the block a few times.  Turned a ring on a Rockwell lathe in 8th grade shop class almost 50 years ago and have never regretted time spent in front of a machine, even when paid a pittance.  I always look forward to finding pre ground used HSS tools at swap meets and metal working shows, just to see profiles that I have not seen before or used.   As rudimentary as they may be any photos of tools that are of use on low hp machines or other wise are a gift as far as I am concerned.
> 
> It is just recently that I have been fooling around with HSS negative rake tooling and am finding that when sharp as a razor and presented at appropriate lead angle it will cut like a hot knife thru butter, yet all these years I have been believing the tale that only positive rake with big reliefs will work with low hp machines.  For me its all about learning, I do this for fun, so yes I would welcome seeing photos of your go to tools even if its a year from now.
> 
> Kind Regards
> michael



Hey Mike, I was trying to fall asleep last night and for some reason your negative rake tooling kept popping into my mind - thanks for that, Buddy!

Anyway, when I visualized the geometry on a negative rake tool it struck me as being similar to a Vertical Shear tool or a Contrary Finishing tool, except with the opposite approach angle. The vertical shear tool is a fine finisher but cannot take a cut more than a few thou deep. I think this is because there is so much contact area at the cutting edge and the edge doesn't last very long. However, on a negative rake tool the forces on the cutting edge are moving away from the cutting edge and the contact area is angled and much smaller. 

I'm sure there is a lot more to this than my simple mind can penetrate right now but at least now I have something to keep me awake when I need to stay conscious. This one is going on my to do list.


----------



## Btroj

This thread has made me look at how I grind tools in a different light.  Being a rank beginner I am very open to new ways of looking at things.

Thanks Mikey, this has made me a grind tools that work much better.


----------



## mikey

Btroj said:


> This thread has made me look at how I grind tools in a different light.  Being a rank beginner I am very open to new ways of looking at things.
> 
> Thanks Mikey, this has made me a grind tools that work much better.




You are most welcome!


----------



## mikey

Hey Guys. This post is in response to a request for more information about how the various tool angles work and how that information can be used to modify your tools if you should choose to do so.

Now, this is going to look very much like a tutorial, which implies that I have some sort of expertise that qualifies me to do a tutorial. I will tell you outright that I don’t. I’m just another hobby guy like you who happens to have done some experimenting over the years and has formed some opinions on how tool geometry works. I am not a tool engineer so the information here is worth exactly what you’re paying for it.

*I want to clarify something up front. I am going to simplify this discussion and take some liberties that allow me to transmit concepts more easily. I’m not lying; I’m avoiding a complex discussion that would otherwise require a long article instead of an easily communicated set of ideas. For example, if I say that increasing a relief angle helps penetration (even Machinery’s Handbook uses this term) that may not be entirely correct. To be correct, I would have to launch into how increasing the angle causes the chip to shear off before the flank of the relief angle contacted the work and then go into the physics of how that affects the three cutting forces and the various types of chip deformation and … well, you get the idea. This is a forum thread and like I did with that article that Joe linked to I would prefer to just keep it intuitive and simple so I can transmit concepts. The important thing is that these concepts, when applied to a turning tool, actually work in real life. If I can get a budding tool grinder to understand these concepts and help him grind a good working tool then the liberties I am taking are acceptable to me. I hope it is acceptable to you.*

Okay, let’s begin with the bottom line:

*What really matters is that you understand what every angle on your tool does; only then can you develop control over it to make your tool do what you need it to do.*

*Edge Angles and Lead Angles*
The side cutting and end cutting edge angles determine the shape of the tool but do not directly alter cutting forces. Nowadays, the older tool shapes are not used as much by hobby guys because our QCTP allow us to rapidly change our tool position. A general purpose tool is more common and provides strength, access to shoulders and more mass that is more forgiving of angle modifications. However, this general shape does require more attention to our lead angles that the side cutting edge angles used to provide automatically because lead angles do directly alter cutting forces.

Remember that when the side cutting edge angle is not at the standard angle provided by a traditional tool then the lead angle will be determined by the side cutting edge angle as you have positioned it and an imaginary line perpendicular to the direction of feed.

As lead angle increases, so do cutting forces because more of the side cutting edge contacts the work. On rigid work pieces this results in better finishes but on thin work this can cause deflection and chatter. I won’t go much more into this other than to say that we want to use as much lead angle as possible (to enhance finishes) as long as there is no chatter. If chatter develops, reduce your lead angle before altering speed and feed.

*Relief Angles*
There are two relief angles on a turning tool – the side relief and end relief angles. They are critical angles because they form half of the cutting edges of the tool.

The primary role of a relief angle is penetration, especially side relief. I’m not talking about penetration in the sense of how easily the tool enters the work; I’m talking about the ease with which the tool moves through the work as it cuts. If you visualize that a greater relief angle will form a more acute included angle at the side cutting edge you can imagine how that angle will cut through the material with greater ease; this is essentially how increasing relief angles reduces cutting forces. Nothing comes for free, however, and we do lose some support under the cutting edge so increasing relief angles may reduce useful edge life. On a hobby lathe in non-production situations this is usually not an issue provided we don’t go crazy with our angle changes.

End Relief angles are usually viewed as support angles (when we think of them at all). If you look at a typical grinding table you will see that the end relief angle is usually about 2-3 degrees less than the side relief angle. This added mass backs the tip of the tool for strength. Unfortunately, it also adds resistance to the cut and retains heat. This is fine if you’re doing long production runs with a heavy lathe on hard materials but that’s not what most hobby guys do, or at least this one. Therefore, it is my practice to equalize the side and end relief angles with the intent of improving shearing action at the tip and to further reduce cutting temperatures. I suggest you consider doing the same. A tool ground this way will cut with greater ease that you can feel and I have yet to break a tip off, even with heavy cuts.

*Rake Angles*
Of all the angles on a turning tool, the rake angles are the most important. They are usually thought of as chip clearance angles, mostly because it’s true. However, they are also the critical upper half of the side and end cutting edges and play a major role in tool penetration, tool life, and cutting force and cutting temperature reduction.

Side rake is the most important variable in your tool’s geometry. Like side relief, increases in side rake will increase the included angle of the side cutting edge so penetration is enhanced and cutting forces decrease as a result. Unlike side relief changes, this advantage comes without affecting support under the cutting edge so tool life is actually improved. Moreover, since increases in side rake promote better chip evacuation we also see reduced cutting temperatures. No other angle change provides so many benefits with so little risk. When lower cutting forces and temperatures are your priority, think about side rake first, relief angles second and back rake third.

Back rake interfaces with the end cutting edge so increases in back rake increases the included angle at the end edge. While you might think this will have little effect, remember that as back rake increases the cutting load shifts from the side cutting edge toward the tip and this can significantly improve finishes. If you want to see the effect of increased back rake, watch a video on how a tangential tool cuts. These tools have what amounts to substantial back rake and as it cuts you will see the chip spiral off the tip. That’s what increasing back rake does – it focuses the cutting forces at the tip. Conversely, as back rake decreases it transfers the cutting load to the side cutting edge. Knowing this allows you to shift where the cutting load is focused; this is a rather useful thing to know, I think. Finally, increasing back rake creates a more positive rake at the cutting tip; this enhances chip flow so cutting temperatures are further reduced.

Changes to side rake and back rake are the closest we will come to a free lunch in tool grinding. Far and away, they are the most useful angles when altering turning tool geometry. We can now see why Machinery’s Handbook says studies show that “… cutting forces and cutting temperatures decrease and tool life increases as side rake and back rake become more positive …” We have mostly upside with very little downside with rake angle changes provided we keep our changes within reason.

*The Thinking Part*
I hope this gives you a clearer picture of what the various tool angles do, which should make it easier to choose which angle to change to enhance the performance aspect you wish to improve. It is important to understand that while we can change a single angle to enhance our geometry, we can also alter multiple angles on the same tool and the effect will be additive. An example of how you might modify a tool with multiple angle changes may help illustrate this.

Say we intend to cut a material that is fairly hard and is known to work harden. 1144 Stressproof steel is a good example of such a material. On a heavy lathe, this steel cuts and finishes very nicely but on a smaller, less rigid lathe it can be a challenge. 1144 roughs well at low speeds but likes very high speeds to finish well. If the surface work hardens due to high temperatures in the cut it can be difficult to take a lighter sizing cut and still hold tolerances or produce the fine finish this steel is capable of. In order for us to work effectively with this material we need to think about how alterations to our tool geometry can enhance our ability to machine it before running into the rigidity and power limits of our lathe.

Clearly, we need to reduce cutting forces so we can rough with a decent cut at a feed rate that won’t stall the lathe or slow it much; this reduces the potential for work hardening. For the same reason we also want to reduce cutting temperatures as much as we can. From the discussion above we know that our first choice will be to increase side rake; this will greatly reduce cutting forces and temperatures with a single change. To further aid in cutting force reduction we could also increase side and end relief by a few degrees without endangering the cutting edge. We can also increase back rake to reduce cutting forces and temperatures even more while improving our finishing potential. Smaller nose radii cut with lower cutting forces because it is easier to bury it in the cut for added support so we will keep our nose radius at about 1/64” and depend on the increased back rake to aid in finishing potential.

Will such a tool really work? Yup, it does. I have one exactly like it, shaped with the above reasoning. On my personal tool, the side and back rake angles were increased by 4 degrees each, while the relief angles were increased by 2 degrees. It will take a much heavier cut than a standard tool and doesn’t seem to work harden the material in the process. As a result, sizing cuts are very accurate and the finish is very good.

Now that we have an idea of how to think of which angle(s) to change the question then becomes: how much do we change each angle for a given tool? The answer is … it depends. Each lathe will differ in degrees of wear, rigidity, power and how the user likes to use that lathe. It also varies with the material being cut. Therefore, there are no pat answers for how much to change an angle.

There are, however, general guidelines we can use. Keep in mind that these are guidelines, not rules. Break them and see what happens – I did.

·  The smaller the lathe the more latitude you have with the number of angles you change and the degree to which you can change them. This is because you will take lighter cuts due to the limited power and rigidity you have so the chances of damaging even a heavily modified tool is small.

·  The more mass in the tool shape, the greater your latitude for angle changes. For this reason, roughing and general use tools are the most forgiving of shapes for us tool modifiers.

·  The harder the material and/or the greater the potential for work hardening, the more emphasis (bigger angle changes) you should put on modifying side rake. I also suggest keeping back rake near baseline to shift the cutting load to the side edge for most hard stuff. You can also boost the relief angles a small amount but be conservative to maximize support under the side cutting edge. Stainless is an exception here; it likes larger relief angles and on a small lathe I add more side rake, too.

·  When finishing potential is your main priority think back rake and relief angles first. Do not forget that lead angle can be very useful when using the tool.

·  To be very clear, when we speak of modifying angles we are speaking of increases to the baseline values already listed in the typical angle table. For example, if side relief is listed as 10 degrees and we wish to increase penetration we may increase side relief by 2-3 degrees for a final angle of 12-13 degrees.

Note also that each angle will vary with the material being cut. That being the case there is no one tool that works for every material and my best advice is to grind at least one good general purpose tool for every material group you commonly work with. Clearly, you must also be familiar with the cutting characteristics of your chosen material (hard, soft, work hardens, etc.)

If you choose to stay with the traditional tool shapes then remember that a rougher cuts with the side cutting edge and tip, a facer cuts primarily with the side cutting edge near the tip and a finisher cuts primarily with the nose. For roughers I change mainly side and back rake; for facers I alter side and end relief and side rake but back rake is left close to standard angles; for finishers I increase side and end relief, side and back rake and increase the nose radius. I leave it to you to figure out why these changes work for the tools involved.

In general, increases to the baseline angles in a grinding table of between 1-5 degrees will produce significant improvements when changing any one angle but when changing multiple angles remember that the improvements will be additive. A few degrees added to both the relief and rake angles may allow you to nearly double your usual depth of cut on a really light lathe so you do not need to be overly aggressive with your changes, especially when changing multiple angles. In fact, it is better to be conservative and selective at first and add more angle in the areas that need it once you see how the tool cuts.

It should now be clear why a tool rest that is settable to precise angles is very useful to a tool grinder. Quite often we will change an angle by only a degree or two so I suggest you leave free hand grinding to those with big lathes and focus on controlling your geometry changes with a good rest. Remember that half the angles at the tool tip are also determined by the angle YOU hold the bit at when grinding them so your skill matters … practice!

The choice of whether or not to alter your tool is up to you. If you choose to change it then I hope this information helps you think through what you’re changing and why you’re changing it. Once you know that and have chosen conservative angle changes to try then grinding the tool is a simple matter of setting your grinding table to the angle you need and grind away. Once you see how the tool cuts you can fine-tune your angle changes until the tool cuts exactly the way you want.

Good Luck!



Mikey


----------



## Bill C.

mikey said:


> Hey Guys. This post is in response to a request for more information about how the various tool angles work and how that information can be used to modify your tools if you should choose to do so.
> 
> Now, this is going to look very much like a tutorial, which implies that I have some sort of expertise that qualifies me to do a tutorial. I will tell you outright that I don’t. I’m just another hobby guy like you who happens to have done some experimenting over the years and has formed some opinions on how tool geometry works. I am not a tool engineer so the information here is worth exactly what you’re paying for it.
> 
> *I want to clarify something up front. I am going to simplify this discussion and take some liberties that allow me to transmit concepts more easily. I’m not lying; I’m avoiding a complex discussion that would otherwise require a long article instead of an easily communicated set of ideas. For example, if I say that increasing a relief angle helps penetration (even Machinery’s Handbook uses this term) that may not be entirely correct. To be correct, I would have to launch into how increasing the angle causes the chip to shear off before the flank of the relief angle contacted the work and then go into the physics of how that affects the three cutting forces and the various types of chip deformation and … well, you get the idea. This is a forum thread and like I did with that article that Joe linked to I would prefer to just keep it intuitive and simple so I can transmit concepts. The important thing is that these concepts, when applied to a turning tool, actually work in real life. If I can get a budding tool grinder to understand these concepts and help him grind a good working tool then the liberties I am taking are acceptable to me. I hope it is acceptable to you.*
> 
> Okay, let’s begin with the bottom line:
> 
> *What really matters is that you understand what every angle on your tool does; only then can you develop control over it to make your tool do what you need it to do.*
> 
> *Edge Angles and Lead Angles*
> The side cutting and end cutting edge angles determine the shape of the tool but do not directly alter cutting forces. Nowadays, the older tool shapes are not used as much by hobby guys because our QCTP allow us to rapidly change our tool position. A general purpose tool is more common and provides strength, access to shoulders and more mass that is more forgiving of angle modifications. However, this general shape does require more attention to our lead angles that the side cutting edge angles used to provide automatically because lead angles do directly alter cutting forces.
> 
> Remember that when the side cutting edge angle is not at the standard angle provided by a traditional tool then the lead angle will be determined by the side cutting edge angle as you have positioned it and an imaginary line perpendicular to the direction of feed.
> 
> As lead angle increases, so do cutting forces because more of the side cutting edge contacts the work. On rigid work pieces this results in better finishes but on thin work this can cause deflection and chatter. I won’t go much more into this other than to say that we want to use as much lead angle as possible (to enhance finishes) as long as there is no chatter. If chatter develops, reduce your lead angle before altering speed and feed.
> 
> *Relief Angles*
> There are two relief angles on a turning tool – the side relief and end relief angles. They are critical angles because they form half of the cutting edges of the tool.
> 
> The primary role of a relief angle is penetration, especially side relief. I’m not talking about penetration in the sense of how easily the tool enters the work; I’m talking about the ease with which the tool moves through the work as it cuts. If you visualize that a greater relief angle will form a more acute included angle at the side cutting edge you can imagine how that angle will cut through the material with greater ease; this is essentially how increasing relief angles reduces cutting forces. Nothing comes for free, however, and we do lose some support under the cutting edge so increasing relief angles may reduce useful edge life. On a hobby lathe in non-production situations this is usually not an issue provided we don’t go crazy with our angle changes.
> 
> End Relief angles are usually viewed as support angles (when we think of them at all). If you look at a typical grinding table you will see that the end relief angle is usually about 2-3 degrees less than the side relief angle. This added mass backs the tip of the tool for strength. Unfortunately, it also adds resistance to the cut and retains heat. This is fine if you’re doing long production runs with a heavy lathe on hard materials but that’s not what most hobby guys do, or at least this one. Therefore, it is my practice to equalize the side and end relief angles with the intent of improving shearing action at the tip and to further reduce cutting temperatures. I suggest you consider doing the same. A tool ground this way will cut with greater ease that you can feel and I have yet to break a tip off, even with heavy cuts.
> 
> *Rake Angles*
> Of all the angles on a turning tool, the rake angles are the most important. They are usually thought of as chip clearance angles, mostly because it’s true. However, they are also the critical upper half of the side and end cutting edges and play a major role in tool penetration, tool life, and cutting force and cutting temperature reduction.
> 
> Side rake is the most important variable in your tool’s geometry. Like side relief, increases in side rake will increase the included angle of the side cutting edge so penetration is enhanced and cutting forces decrease as a result. Unlike side relief changes, this advantage comes without affecting support under the cutting edge so tool life is actually improved. Moreover, since increases in side rake promote better chip evacuation we also see reduced cutting temperatures. No other angle change provides so many benefits with so little risk. When lower cutting forces and temperatures are your priority, think about side rake first, relief angles second and back rake third.
> 
> Back rake interfaces with the end cutting edge so increases in back rake increases the included angle at the end edge. While you might think this will have little effect, remember that as back rake increases the cutting load shifts from the side cutting edge toward the tip and this can significantly improve finishes. If you want to see the effect of increased back rake, watch a video on how a tangential tool cuts. These tools have what amounts to substantial back rake and as it cuts you will see the chip spiral off the tip. That’s what increasing back rake does – it focuses the cutting forces at the tip. Conversely, as back rake decreases it transfers the cutting load to the side cutting edge. Knowing this allows you to shift where the cutting load is focused; this is a rather useful thing to know, I think. Finally, increasing back rake creates a more positive rake at the cutting tip; this enhances chip flow so cutting temperatures are further reduced.
> 
> Changes to side rake and back rake are the closest we will come to a free lunch in tool grinding. Far and away, they are the most useful angles when altering turning tool geometry. We can now see why Machinery’s Handbook says studies show that “… cutting forces and cutting temperatures decrease and tool life increases as side rake and back rake become more positive …” We have mostly upside with very little downside with rake angle changes provided we keep our changes within reason.
> 
> *The Thinking Part*
> I hope this gives you a clearer picture of what the various tool angles do, which should make it easier to choose which angle to change to enhance the performance aspect you wish to improve. It is important to understand that while we can change a single angle to enhance our geometry, we can also alter multiple angles on the same tool and the effect will be additive. An example of how you might modify a tool with multiple angle changes may help illustrate this.
> 
> Say we intend to cut a material that is fairly hard and is known to work harden. 1144 Stressproof steel is a good example of such a material. On a heavy lathe, this steel cuts and finishes very nicely but on a smaller, less rigid lathe it can be a challenge. 1144 roughs well at low speeds but likes very high speeds to finish well. If the surface work hardens due to high temperatures in the cut it can be difficult to take a lighter sizing cut and still hold tolerances or produce the fine finish this steel is capable of. In order for us to work effectively with this material we need to think about how alterations to our tool geometry can enhance our ability to machine it before running into the rigidity and power limits of our lathe.
> 
> Clearly, we need to reduce cutting forces so we can rough with a decent cut at a feed rate that won’t stall the lathe or slow it much; this reduces the potential for work hardening. For the same reason we also want to reduce cutting temperatures as much as we can. From the discussion above we know that our first choice will be to increase side rake; this will greatly reduce cutting forces and temperatures with a single change. To further aid in cutting force reduction we could also increase side and end relief by a few degrees without endangering the cutting edge. We can also increase back rake to reduce cutting forces and temperatures even more while improving our finishing potential. Smaller nose radii cut with lower cutting forces because it is easier to bury it in the cut for added support so we will keep our nose radius at about 1/64” and depend on the increased back rake to aid in finishing potential.
> 
> Will such a tool really work? Yup, it does. I have one exactly like it, shaped with the above reasoning. On my personal tool, the side and back rake angles were increased by 4 degrees each, while the relief angles were increased by 2 degrees. It will take a much heavier cut than a standard tool and doesn’t seem to work harden the material in the process. As a result, sizing cuts are very accurate and the finish is very good.
> 
> Now that we have an idea of how to think of which angle(s) to change the question then becomes: how much do we change each angle for a given tool? The answer is … it depends. Each lathe will differ in degrees of wear, rigidity, power and how the user likes to use that lathe. It also varies with the material being cut. Therefore, there are no pat answers for how much to change an angle.
> 
> There are, however, general guidelines we can use. Keep in mind that these are guidelines, not rules. Break them and see what happens – I did.
> 
> ·  The smaller the lathe the more latitude you have with the number of angles you change and the degree to which you can change them. This is because you will take lighter cuts due to the limited power and rigidity you have so the chances of damaging even a heavily modified tool is small.
> 
> ·  The more mass in the tool shape, the greater your latitude for angle changes. For this reason, roughing and general use tools are the most forgiving of shapes for us tool modifiers.
> 
> ·  The harder the material and/or the greater the potential for work hardening, the more emphasis (bigger angle changes) you should put on modifying side rake. I also suggest keeping back rake near baseline to shift the cutting load to the side edge for most hard stuff. You can also boost the relief angles a small amount but be conservative to maximize support under the side cutting edge. Stainless is an exception here; it likes larger relief angles and on a small lathe I add more side rake, too.
> 
> ·  When finishing potential is your main priority think back rake and relief angles first. Do not forget that lead angle can be very useful when using the tool.
> 
> ·  To be very clear, when we speak of modifying angles we are speaking of increases to the baseline values already listed in the typical angle table. For example, if side relief is listed as 10 degrees and we wish to increase penetration we may increase side relief by 2-3 degrees for a final angle of 12-13 degrees.
> 
> Note also that each angle will vary with the material being cut. That being the case there is no one tool that works for every material and my best advice is to grind at least one good general purpose tool for every material group you commonly work with. Clearly, you must also be familiar with the cutting characteristics of your chosen material (hard, soft, work hardens, etc.)
> 
> If you choose to stay with the traditional tool shapes then remember that a rougher cuts with the side cutting edge and tip, a facer cuts primarily with the side cutting edge near the tip and a finisher cuts primarily with the nose. For roughers I change mainly side and back rake; for facers I alter side and end relief and side rake but back rake is left close to standard angles; for finishers I increase side and end relief, side and back rake and increase the nose radius. I leave it to you to figure out why these changes work for the tools involved.
> 
> In general, increases to the baseline angles in a grinding table of between 1-5 degrees will produce significant improvements when changing any one angle but when changing multiple angles remember that the improvements will be additive. A few degrees added to both the relief and rake angles may allow you to nearly double your usual depth of cut on a really light lathe so you do not need to be overly aggressive with your changes, especially when changing multiple angles. In fact, it is better to be conservative and selective at first and add more angle in the areas that need it once you see how the tool cuts.
> 
> It should now be clear why a tool rest that is settable to precise angles is very useful to a tool grinder. Quite often we will change an angle by only a degree or two so I suggest you leave free hand grinding to those with big lathes and focus on controlling your geometry changes with a good rest. Remember that half the angles at the tool tip are also determined by the angle YOU hold the bit at when grinding them so your skill matters … practice!
> 
> The choice of whether or not to alter your tool is up to you. If you choose to change it then I hope this information helps you think through what you’re changing and why you’re changing it. Once you know that and have chosen conservative angle changes to try then grinding the tool is a simple matter of setting your grinding table to the angle you need and grind away. Once you see how the tool cuts you can fine-tune your angle changes until the tool cuts exactly the way you want.
> 
> Good Luck!
> 
> 
> 
> Mikey




Thank you, well said


----------



## mikey

Thanks, Bill. Appreciate it.


----------



## mikey

JR49 said:


> So, too all the beginners on this forum, myself included, Lets man up and ask all the basic questions that we've been wondering about, but didn't want to admit we didn't know.



Just woke up and reviewed my last post and it suddenly dawned on me that while I tried to simplify things as much as I could there are going to be some beginning tool grinder guys out there that don't even know what a side cutting edge angle is, let alone how it relates to the lead angle of the tool. I am a noob too, in so many, many ways and I wanted to tell you guys that if you are unclear about something I said or anything else we said in this thread then you need to ask so one of us can clarify it. Please trust me that as basic and silly as your question may seem to you, there are ten more guys with the same question that won't voice it. Back when I started to grind tools there was no internet and nobody to ask - what I would have given to have what you have right in front of you!


----------



## Round in circles

Seeing how this is about grinding  the tool tip , I'd like to ask a  question that has been puzzling me as I seem to have a mental block about something.



I have a QCTP on my old lathe 
 I want to bore an inch hole through some 2.5 " x 3 " long round M/S bar  & at either end of the newly made " tube " I want to open it out to take a 1 &3/4 " OD  sealed roller bearing unit that is 1/2" wide.

I've given it quite a lot of thought of how to ensure that the bearing will be secured and am going to use circlips but I can't quite visualize  what sort of ground tip I need to make so I can clean out the recess so it has a 90 degree face to the turned 1 & 3/4 holes  internal face . ( have no problems accurately using a grind stone ) 
I have some rather weedy boring bars hand ground to almost an off set round with a spade type tip on the end   from 1/2"  sq HSS bar but the cutting end face that would be at the internal flat face of the boring is angled to about 30 degrees and as that is a the other half of a thread angle I'm loath to alter it .

Can some of you more experienced guys sketch  what sort of grinds I can put on some new 1/2 " square HSS bar for me to make this cutter , as I'm not sure if a simple grind of face and angling the QCTP a tad will suffice when it hits the back wall  ?


----------



## JR49

Round in Circles,  not sure if I'm understanding correctly, but if I am, you can  grind the 1/2 " tool so that it will go straight in like a boring bar.  If you cut the little parting tool at the front perfectly perpendicular to the tool bit then, just be sure that the tool is parallel with lathe axis, and the groove will have a  90 deg. face.  See my sketch, hope this helps, JR49
	

		
			
		

		
	



EDIT, if you have a boring bar that holds a 1/4" or smaller bit at  90* to the bar, you can use that and have less grinding.  good luck


----------



## mikey

Let me be sure I understand you. You are going to bore a 1" through hole through the stock, then on each end you plan to open up that center bore to house a bearing on each end and hold the bearing in place with a retaining ring, right? You seem to need a boring bar that will bore a flat face at the bottom of the bearing bore.

Grinding a boring bar is not difficult but it is time consuming, especially in HSS. Personally, I would not bother. You can buy a boring bar with a 5 degree positive lead and do that bore in no time. Likewise, you can buy a grooving bar to suit the ring you plan to use and get the job done quickly and well. I'm not trying to discourage you from grinding your own tools. I saying that for me it is not worth the time and effort to do so. With that said ...

How are you planning to do the center bore? Can't you use that same bar to open up the ends? 

You can grind a grooving tool like JR shows; just be sure you round the underside of the cutting edge to provide adequate clearance.


----------



## Round in circles

JR & Mikey,
I have the tool to make the circlip retaining grove .

This by Mikey ,is what I'm after " You seem to need a boring bar that will bore a flat face at the bottom of the bearing bore "

The 1 " centre bore was going to be done using MT drills in the tail stock as I have a few that will get me there .
It is indeed the flat face at the bottom of the bearing bore  that I'm  having mind games with .

Mikey  your  post has  have triggered an avalanche in the old grey matter container , I think I've got it sussed using stuff I already have guys .


----------



## mattthemuppet2

you're going to really struggle to get that face flat using that boring bar. Does the other end have a hole for a hss bit at 45deg instead of 90? If so, as long as it's sticking out far enough, you'll be able to grind a bit that will do the job. You'll need some relief at the face (the side of the tool closest to the face of the bore) and I'd probably grind it with some back rake (from the tip to the boring bar) but no side to side top rake (so the top neither slopes to the left or right of the bit, looking at the tip). Make sure the front of the tool has enough relief not to rub on the side of the bore that you're starting with.

If that bar doesn't have a 45deg hole in the other end, you could make one relatively easily by milling a slot at the right angle, slitting the back of the slot and putting a pinch screw on the top (if you have clearance).


----------



## mikey

You might also be able to do this with a simple knife tool, which you probably have already. If you position the tool nearly parallel to the spindle axis but with the tip slightly toward the outside (negative lead angle) you can feed out from the center bore and stop at your desired ID, making multiple passes until you reach the desired bore depth. I do this all the time to make shallow depressions on the end of a part.


----------



## Round in circles

mattthemuppet said:


> you're going to really struggle to get that face flat using that boring bar. Does the other end have a hole for a hss bit at 45deg instead of 90? If so, as long as it's sticking out far enough, you'll be able to grind a bit that will do the job. You'll need some relief at the face (the side of the tool closest to the face of the bore) and I'd probably grind it with some back rake (from the tip to the boring bar) but no side to side top rake (so the top neither slopes to the left or right of the bit, looking at the tip). Make sure the front of the tool has enough relief not to rub on the side of the bore that you're starting with.
> 
> If that bar doesn't have a 45deg hole in the other end, you could make one relatively easily by milling a slot at the right angle, slitting the back of the slot and putting a pinch screw on the top (if you have clearance).


 I understand what you have said, sadly the bar is square at the other end ... I don't have a milling machine nor a lathe milling attachment ( pathetic aren't I  )


----------



## Round in circles

mikey said:


> You might also be able to do this with a simple knife tool, which you probably have already. If you position the tool nearly parallel to the spindle axis but with the tip slightly toward the outside (negative lead angle) you can feed out from the center bore and stop at your desired ID, making multiple passes until you reach the desired bore depth. I do this all the time to make shallow depressions on the end of a part.




Got it , I may have such a HSS knife tool that cuts at/towards the left top edge .. I may have to sculpt it a tad to give a bit more clearance as the bearing bore hole will be about 3/4 deep.

 Many thanks


----------



## mattthemuppet2

you don't have to have a mill, I'm sure you could manage with a drill press (or hand drill if you have to), a saw and some files. 

If the recess is only 3/4in deep you can easily grind a 3/8 square bit to do that. Looking at the front, grind the sides into a 1/4 circle (ie. the bottom right quarter of a circle) for about an inch. Then grind the  same side from ~1/4 from the tip to the full inch a little more. Grind the 1st 1/4in so that the tip angles slightly at the side to meet that recess you just ground. Grind the front a wee bit, say 5deg or so, both top to bottom and left to right. Then you can grind the top for a bit of rake if you want. Stone it and you're done, easy peasy.


----------



## mikey

Round in circles said:


> Got it , I may have such a HSS knife tool that cuts at/towards the left top edge .. I may have to sculpt it a tad to give a bit more clearance as the bearing bore hole will be about 3/4 deep.
> 
> Many thanks



You shouldn't have to alter the tool. Just angle the tip about 5 degrees off center. You are orienting the tool like a boring bar, with the tip pointed slightly to your left. Most knife tools should have more than enough relief under the cutting edge to make this cut and the shank of the tool will not even come close to touching the edge of that bore.


----------



## Round in circles

mattthemuppet said:


> you don't have to have a mill, I'm sure you could manage with a drill press (or hand drill if you have to), a saw and some files.
> 
> If the recess is only 3/4in deep you can easily grind a 3/8 square bit to do that. Looking at the front, grind the sides into a 1/4 circle (ie. the bottom right quarter of a circle) for about an inch. Then grind the  same side from ~1/4 from the tip to the full inch a little more. Grind the 1st 1/4in so that the tip angles slightly at the side to meet that recess you just ground. Grind the front a wee bit, say 5deg or so, both top to bottom and left to right. Then you can grind the top for a bit of rake if you want. Stone it and you're done, easy peasy.



To the first ......Sadly no ,  I've recently had a second spinal operation , it's left my shoulders & spinal muscles decidedly weak .
At present I couldn't pull the skin off a rice pudding let alone push a fine file through a round hole to make it square. 

To the second  , that is kind of what I'd envisaged before I mentioned the boring bar idea .


----------



## Round in circles

mikey said:


> You shouldn't have to alter the tool. Just angle the tip about 5 degrees off center. You are orienting the tool like a boring bar, with the tip pointed slightly to your left. Most knife tools should have more than enough relief under the cutting edge to make this cut and the shank of the tool will not even come close to touching the edge of that bore.




 Mikey & others you have given me much ammunition to go shooting with  ......thanks.

 I think I'll have to have a play with a bit of 1 & 1/4 " aluminium round to see roughly how it works out before I let my skills or lack of them loose on the turnable cold rolled steel I specifically purchased for the job.


----------



## mikey

Some time ago, Doubleeboy asked me for some pics of my tools but my camera was on loan for some time - I just got it back. I was sorely tempted to grind some new tools to show but decided to show a few of my oldest working tools instead. Two of these are very old and used and in need of regrinding, and my aluminum cutter is only a few months old.

Each of these tools is honed with a diamond hone after every use and show some marks but I assure you they are sharp enough to easily slice paper or a finger. Oh, and they cut metal well, too.

Shown here are my 15 year old Knife Tool, a cutter for tool steels/1144 steel, and an aluminum cutting tool:




This is the top and side cutting edge of my cobalt Knife Tool. As you can see, its time to regrind it; most of the back rake has been ground off but it still cuts so well that it sort of justifies my laziness. This tool faces everything I put it to with a mirror finish and will cut a very tight, clean shoulder. It also can take a cut in thin work pieces so fine that the chips come off like dust. I made this tool about 15 years ago, never reground it and it still cuts like new.





Here is my tool steel cutter. This tool is very old, probably 10 years since it saw a grinder, and should have been reground a long time ago. The tool marks on the top face are from my hone, not grind marks. The side and end relief angles and the side rake angles are all larger than normal to enhance the tool's performance in harder steels. As you can see, the back rake has been mostly honed off over time and needs to be re-established. Still, this tool will take a roughing cut in 1144 steel without work hardening it much, which allows a fine sizing or finishing cut. It has more mass in its overall shape to allow for the increased tool angles.





Here is an Aluminum cutter I ground a few months ago. This tool has a general shape but since it is ground on a belt sander the rake angles look weird. When it is ground the belt is shifted off to the side of the platen by about 1/16"; this prevents the belt from being cut as I grind. Due to the extreme back rake angle of about 40 degrees the tool tends to push the belt back toward the center of the platen. As it does so, it cuts a curve into the side and back rake angles. The angles are correct but the shape is distorted; there is a curve rather than a definite step as we would normally see. This is not an issue for tools with normal amounts of back rake but on aluminum cutters, it can be. While this technicality exists, the tool cuts fine and this tool can take a very heavy cut while leaving a clean finish. I sharpen the side and end with a normal diamond hone but use a round diamond hone to hone the rake angles. You can see some residual grind marks on the top because I can't get them all out without altering the rake angles so I just get the edge razor-sharp and leave it at that. When the chips come off they curl tightly, which is nice.





As I said, it was tempting to grind new tools so I could show off. I can actually grind a really pretty tool but that isn't what Doubleeboy asked for. These are some of my most frequently used working tools that are all modified to do what I want them to do. My other tools are also general purpose tools with varying amounts of modified relief and rake angles to suit different material classes.

I chose these tools because I wanted to point something out. All of them have highly modified rake and relief angles, or used to when they were new. The shape of the steel and aluminum cutters shown here have more mass to allow for these changes. That is, the side cutting edge angle is less acute than my normal general purpose shape would have. This is just my personal approach - when I increase relief and rake angles a lot then I add more mass in the tip to support those changes. This is especially true when the material being cut is hard, like my tool steel cutter, or when the rake and relief angles create a very positive angle at the tip which makes the tip more fragile, like my aluminum cutter. More mass adds strength.


----------



## Doubleeboy

Great photos mikey, thank you!   I first stood in front of a lathe when I was in middle school shop class, close to 50 years ago, its safe to say I have been around the block once or twice.  Yet when I have a chance to visit other folks shops its not their projects that first catch my attention its their hand ground cutters, then to hear what cutters are used in what materials.   Anyone who wants to increase their understand of cutting would do well to consider your cutters and grind up one or two.   If the newbies spent the time to understand hand ground technique instead of buying those dreadful 5 piece sets of Chinese carbide insert tools they would advance their skill set much quicker.



Thanks again,
michael


----------



## mikey

Thanks, Mike. Sorry it took so long to get these posted. I'll try to find the time to grind some new tools and when I do I will update these pics so you can see what the tools should actually look like. 10-15 years of wear on a tool is a bit much, I'm embarrassed to say.

I did want to encourage others, especially the newer hobbyists, to have a go at tool grinding. I think there is enough info in this thread and references to give you a fair shot at it. I'm not a tool grinding guru by any means but if I can help, let me know.


----------



## markknx

Doubleeboy said:


> Great photos mikey, thank you!   I first stood in front of a lathe when I was in middle school shop class, close to 50 years ago, its safe to say I have been around the block once or twice.  Yet when I have a chance to visit other folks shops its not their projects that first catch my attention its their hand ground cutters, then to hear what cutters are used in what materials.   Anyone who wants to increase their understand of cutting would do well to consider your cutters and grind up one or two.   If the newbies spent the time to understand hand ground technique instead of buying those dreadful 5 piece sets of Chinese carbide insert tools they would advance their skill set much quicker.
> 
> 
> 
> Thanks again,
> michael


I think it is the fear of not getting the grind right. I know I was leery of grinding my own HSS. And I had been grinding drill bits for many years. I think a company could do well that if they offered a set of preground HSS bits. This would also give new guys a chance to see a bit so they know how to grind their own  and how it should look.
Mark


----------



## Doubleeboy

Mark, 

I believe in the past and maybe currently some outfits like Sherline or Little Machine Shop, or Grizzly have sold bits that are already ground. 

What I think a lot of guys miss when the start with carbide is the understanding of cutting action and forces that you gradually learn when you do it yourself.  When you add a couple more degrees of relief under the front cutting edge and voila you go from rubbing and barely cutting to taking off material easily the light goes on in your brain.  Then you experiment with nose radius and find the sweet spot between fine finish and chatter.  Fool around with top rake, negative, neutral, positive, see the difference in power required to make a cut.

I completely agree that purchasing a set of pre ground bits and keeping them for models would be a good call for lots of folks.  Then make your own versions of them and fool with the different parameters one at a time.  Mikey's photos should help some folks if the use them as models.   Not being afraid of failure is half of the challenge.  Being willing to keep going between the grinder and lathe and only changing one thing at a time are the key IMO.

cheers
michael


----------



## markknx

Michael,
Yes, yes, all good points.  I know I would either still be struggling or have given up if it wasn't for this group and some good you tube videos on grinding HSS tool bits. I'm no expert but I can make them cut.


----------



## mikey

Hey Mark, I had the very same idea - buy a preground set so I could learn how the tool should be ground. I bought Sherline's set and, over time, learned to match them. The problem is that the tip geometry on those tools is not what I consider "proper" but I didn't know that then. I do now.

I've thought long and hard about this and I'll tell you what would help me if I were starting out. I would want a guy to tell me what I'm doing at every single step of the way. I mean, how do I angle the tool rest and how to hold the tool bit in relation to the grinding media? I would want to know what each hand is doing; which one moves side to side and where the other puts the pressure to make the grinding media cut. What am I looking to create on every face I grind and why? The side and end faces are easy to grind. Its the top rake angles that are difficult for most guys and they are probably the most important angles on that tool so it has to be right. I would want to know how to set up the rake angles and how to feed the bit into the grinder to create them. If I knew all of that then grinding the tool would be easier, as would modifying those angles if I chose to do so.

I tried to do that in my MachinistBlog articles but I had a lot to cover and didn't put as much detail into the grinding part as I would have liked. If you guys think this might be something that would help then I can grind  an actual tool and detail what I'm doing at every step of the process, complete with pictures and arrows and stuff. If that would help then let me know. I have to grind a new tool steel cutter anyway and I can take the pics as I do that.


----------



## markknx

Mikey,
I have got that all  down. But it would be a good source for other guys that are starting out.
Mark


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## mikey

Okay, just thought I would make the offer.


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## Bill C.

JR49 said:


> Round in Circles,  not sure if I'm understanding correctly, but if I am, you can  grind the 1/2 " tool so that it will go straight in like a boring bar.  If you cut the little parting tool at the front perfectly perpendicular to the tool bit then, just be sure that the tool is parallel with lathe axis, and the groove will have a  90 deg. face.  See my sketch, hope this helps, JR49
> 
> 
> 
> 
> 
> 
> 
> 
> 
> View attachment 109133
> 
> EDIT, if you have a boring bar that holds a 1/4" or smaller bit at  90* to the bar, you can use that and have less grinding.  good luck



He is asking the best way to clean up a shoulder cut after drilling and boring.  Your bit design would work fine. He would need to set the depth either with a stop or indicator. In your drawing you show a undercut so there will not be any question the shoulder is sharp and clean.  He should grind the the clearance area behind the cutting area so the bit can be used on deeper shoulders.


----------



## mikey

I decided to grind a Square Tool to show how it looks. This is a 3/8" HSS bit from Japan and it is quite a good blank. As you may recall, my Square Tool is ground with 15 degree relief and rake angles and will do a decent job on most common materials we find in a hobby shop. This one has a 1/32" nose radius on it. All grinding was done on my belt sander with a 24 grit AO belt.

This is the ground tool from the side. Note that the tip is at the same height as the shank of the tool, which means the grind extends all the way to the tip ... but no more.




This is the top surface of the tool before honing.




This is the side after honing.




The top.




The end.



And an oblique view.




The tool is honed with diamond stones and the nose radius is then stoned to shape and blended with the side and end faces. It is razor sharp and the tool cuts very well.


----------



## Bill C.

mikey said:


> I decided to grind a Square Tool to show how it looks. This is a 3/8" HSS bit from Japan and it is quite a good blank. As you may recall, my Square Tool is ground with 15 degree relief and rake angles and will do a decent job on most common materials we find in a hobby shop. This one has a 1/32" nose radius on it. All grinding was done on my belt sander with a 24 grit AO belt.
> 
> This is the ground tool from the side. Note that the tip is at the same height as the shank of the tool, which means the grind extends all the way to the tip ... but no more.
> 
> View attachment 111286
> 
> 
> This is the top surface of the tool before honing.
> 
> View attachment 111287
> 
> 
> This is the side after honing.
> 
> View attachment 111288
> 
> 
> The top.
> 
> View attachment 111289
> 
> 
> The end.
> View attachment 111290
> 
> 
> And an oblique view.
> 
> View attachment 111291
> 
> 
> The tool is honed with diamond stones and the nose radius is then stoned to shape and blended with the side and end faces. It is razor sharp and the tool cuts very well.



Nice job of design and grinding


----------



## JR49

Great job, Mike!  These pics are going on file with your grinding posts that I have saved.  You must have been a teacher in another life.  JR49


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## Doubleeboy

Maybe the management of the site could make Mike's photos and write up a sticky in this section, so that folks can easily find it to refer back to it.

Great photos!!!
michael


----------



## mikey

Thanks for your kind words, Guys - I appreciate it. I hope the pics show the various angles so folks have a better idea of what we've been talking about here. It isn't as good as a tool-in-the-hand like Mark was talking about but its better than nothing.

As I was grinding the tool above the belt snapped at the splice and I swear I must have jumped about 4 feet in the air! It happened just as I was completing the rake grind on top of the tool so I was standing very close to the belt and ... POOWWW! I had a replacement belt but it was from the same lot as the one that snapped so getting up close to it to finish the tool took some nerve, but I did it. Then I went and washed my shorts!


----------



## markknx

Nice Mikey, Sorry I did not get back to you earlier. Yes the offer was a good one and like others I think your work should be posted some place easy to find for guys trying to get a grip on grinding. Or even improve their skills. Like me I'm never against learning new ways of doing things.


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## mikey

markknx said:


> Nice Mikey, Sorry I did not get back to you earlier. Yes the offer was a good one and like others I think your work should be posted some place easy to find for guys trying to get a grip on grinding. Or even improve their skills. Like me I'm never against learning new ways of doing things.



Thank you, Mark. My offer to do a tutorial/pictorial stands if there is any interest.


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## Joe Pitz

Thanks Mikey and everyone,  the pics are great and will definitely give me a good example of what to shoot for when grinding my own tooling. 

I agree this post should be turned into a sticky in the Beginner's forum.

Joe


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## mikey

You're welcome, Joe. 

I should note that I normally do not hone the top of the tool quite so much, at least not enough to create a step and lower the top of the tool as I did. This happened because I didn't have a fresh 80 grit belt to smooth out the tool after I shaped it with my 24 grit belt. My belts were over 2 years old and the splice was giving out so I chose to hone the grind marks out rather than risk my hands. Ordinarily, the top rake would not show a step.


----------



## Strtspdlx

Alright Mikey now we have pictures of your work. Needless to say I'm rethinking my entire tooling collection now. I normally grind no back rake in my tooling. I try to grind 15-20* "slant" on the top(sorry I still for the life of me cannot remember the correct terminology. I think I will try it on my grinder some time this week. As far as honing goes. How important would you say it is to use a diamond home verse a standard hardware store knife sharpening stone? I do have a belt sander I just need to find a motor for it and some other miscellaneous parts. Seeing your tools I may have to make that a priority. I definitely want to try a tool with that much back take. As I said I normally grind with none. But some of my tools May have an ever so slight back rake. Also are you using all your tools in a qctp that holds the tools horizontal or a latern style that normally has about left right or straight tool holder with preset of 15* back rake?


Regards-Carlo


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## Bill C.

When you get the tool bit shaped and sharpen the way you like find a way to mark it or store it so in six months from now you will remember what it was used for.  

About everyone of us have a few bits we use more than others. I think I may have six HHS bits I used almost all the time.


----------



## mattthemuppet2

you can play with side and back rake to get the chips curling at the DOC you want to use - more rake tends to = curlier chips - but if you take it too far the tip won't hold up as well plus the bit can start digging in, on brass or gummy alu for example. 

as for honing, store knife stones may be too coarse. I've used a medium and a hard Arkansas stone (I think I posted the link earlier) for years with great success and recently got a fine diamond hone which is a little easier to use but gives the same result. I tend to leave that one for touching up carbide bits.


----------



## mikey

Strtspdlx said:


> Alright Mikey now we have pictures of your work. Needless to say I'm rethinking my entire tooling collection now. I normally grind no back rake in my tooling. I try to grind 15-20* "slant" on the top(sorry I still for the life of me cannot remember the correct terminology. I think I will try it on my grinder some time this week. As far as honing goes. How important would you say it is to use a diamond home verse a standard hardware store knife sharpening stone? I do have a belt sander I just need to find a motor for it and some other miscellaneous parts. Seeing your tools I may have to make that a priority. I definitely want to try a tool with that much back take. As I said I normally grind with none. But some of my tools May have an ever so slight back rake. Also are you using all your tools in a qctp that holds the tools horizontal or a latern style that normally has about left right or straight tool holder with preset of 15* back rake?
> 
> 
> Regards-Carlo




Hi Carlo, glad to hear from you. 

As long as the stone is flat and it removes the grinding marks you should be fine. I prefer diamond stones only because they stay flat and cut efficiently for a long time. They do cost more, though.

If you can grind side rake then you can grind back rake, Carlo. Both angles are ground at the same time and are very simple to do. Not using back rake is your choice, of course, if it is a choice. However, if you are not sure how it is ground then that's another thing. If that is the case, let me know.

I do use an Aloris QCTP, not a lantern tool post.

I use a belt sander because it is much faster and easier to grind tools. It is also theoretically safer. However, as good as it is, it is the tool rest that makes it so easy to use.


----------



## mikey

mattthemuppet said:


> ... as for honing, store knife stones may be too coarse. I've used a medium and a hard Arkansas stone (I think I posted the link earlier) for years with great success and recently got a fine diamond hone which is a little easier to use but gives the same result. I tend to leave that one for touching up carbide bits.



I like stones for some work too, Matt. I use a fine India followed by a translucent Arkansas on my gravers and the edge is superb. Using diamond stones I can put an edge on my turning tools that will slice a clean cut in paper or a finger with no problem but I could do surgery with my gravers.


----------



## Strtspdlx

mikey said:


> Hi Carlo, glad to hear from you.
> 
> As long as the stone is flat and it removes the grinding marks you should be fine. I prefer diamond stones only because they stay flat and cut efficiently for a long time. They do cost more, though.
> 
> If you can grind side rake then you can grind back rake, Carlo. Both angles are ground at the same time and are very simple to do. Not using back rake is your choice, of course, if it is a choice. However, if you are not sure how it is ground then that's another thing. If that is the case, let me know.
> 
> I do use an Aloris QCTP, not a lantern tool post.
> 
> I use a belt sander because it is much faster and easier to grind tools. It is also theoretically safer. However, as good as it is, it is the tool rest that makes it so easy to use.


I wouldn't say I don't know how to make the angle. I'm not sure in my case it's completely necessary. Grinding isn't hard for me. Can it be tricky of course. In just considering the fact that standard all my lantern style took holders have I believe a 15* back rake already built into the holder. So do I need additional back rake or is this mainly used when you're using holders that hold the tool perfectly perpendicular to the work?
Also I've been watching this thread. Just not commenting because I should sit back and listen sometimes. And the. Everything got busy and life over ruled everything. I haven't touched my lathe in probably 3-4 months. It's very depressing. I need to get back at it. 


Regards-Carlo


----------



## mikey

If you're using a lantern tool post that angles the bit upward then it is assumed this provides back rake so you may not need more than that for ferrous materials. You may need more for aluminum, and significantly less for brass. As long as you know how to accommodate your materials then you're all good, Carlo.

I don't use these posts but if I did then I think tool geometry would be very interesting.

Yeah, life has a way of getting in the way of things sometimes. Hope you're okay.


----------



## Strtspdlx

I'm fine. Just too much in the pile at once. I have a bunch of blanks I'd like to grind and see if I can't use some of the knowledge I. This thread. I need to fix that belt sander I have. It would be really nice to use it. I also have a fairly good stock of larger tool blanks for when I get a qctp I didn't want to purchase one until I got a larger lathe but that won't happen till after I purchase a mill and that won't happen for a good bit of time. 


Regards-Carlo


----------



## Strtspdlx

So I put a bit of back rake in my tools because when I looked at the angle the cutter was at when In the tool post it was basically level or slightly nose down. That would be negative rake?  So I put some back rake into the tool approximately 8-12* and wow. What a difference. I really need to figure out chip control though. The Long curlies are getting to be annoying. Finish and cut effort wise it's a whole different animal. The machine sounds so less loaded even in a .050 cut. 


Regards-Carlo


----------



## Doubleeboy

Carlo, you can control chip stringiness to some degree without a chip breaker by varying your feed or speed.  So If you are turning 1020 or 1018 and you are getting stings on your roughing cut try taking a deeper cut, or faster feed or change your speed.  Using cobalt HSS I like a lightly tan chip, with plane old chinese budget hss I like a little less than tan.  I keep a bent coat hanger to rip strings with if necessary.  Sometimes you find the feed and speed and depth of cut you want for a fine finish and still get strings, I just rip em out of way before they ball up on the chuck or toolpost.

cheers
michael


----------



## mikey

Glad you gave it a try, Carlo. You're right; if the tip slants down, that is a negative rake. This works but you need a lot more power and rigidity to use it well. 

I'm glad you gave back rake a try. Now you can play with your tool angles until you find what works for you. I would guess that boosting the side relief and side rake angles a little will further reduce cutting forces and allow your lathe to cut with less effort, too. 

I agree with Mike - our cutting conditions (speed, feed, DOC) have a lot to do with chip formation, as does the material we are cutting and our tool geometry. Stainless and Aluminum in particular like to form stringy chips that are sharp and dangerous. I tend to take very heavy roughing DOC with these to reduce this tendency. Hand feeding also helps to break the chips off.  Then I take a light finishing pass with power feed to get the finish I want. My stainless tool has a lot more side relief and my aluminum tool has more back rake than normal and these changes help in those materials.


----------



## Strtspdlx

I think before I
Mess with angles too much I either need to fix my belt sander or get a stone dresser for my bench grinder. It is t completely flat which makes it challenging to get an even finish on my tooling. I've thought about using chip breakers also but I've heard they take more tool pressure to properly use. Is this true? Also on tooling this small. 3/8" I believe. What is the best way to grind a chip breaker? I doubt I could grind it using the corner of the wheel. 


Regards-Carlo


----------



## Joe Pitz

Hey Carlo,

Adam Booth has several videos on chip control and cutting a chip breaker.














One thing to note though,  he is using a heavy lathe,  so he is not applying the steeper back rake and side rake/relief angles that mikey has suggested to adjust.

But otherwise, some nice videos on the performance you can get using HSS tools. 

He is using 1/2" tool blanks, but you can apply most of his technique using 3/8" tool blanks.

You might be able to cut the chip breaker with a diamond tile saw  or a Dremel tool.

Thanks

Joe


----------



## mikey

Those videos are impressive! Big lathe taking very big cuts - Wow!!!

Chipbreakers work, no doubt about it. I've messed with them in the past, mostly to try to deal with the chips from Aluminum and Stainless, but decided that the hassle to grind them wasn't worth the effort. It was an honest effort over about a 6 month period that varied width, depth, angles and closeness of the channel to the cutting edge. When I tried them they curled the chips into more compact curls that eventually broke off so there were no 4 foot long Aluminum chips going past me. My real problem with them is keeping my tools sharp. Dunn0, maybe I'm doing it wrong. 

I have ground them in both 1/4" and 3/8" bits with the corner of my grinding wheel and also used a Dremel and an air die grinder using fiber reinforced abrasive cutting wheels and found that it is very fiddly to get the edge of the chipbreaker channel to line up precisely with the side cutting edge. In the video, Adam is not trying to do this but that may be because he has a lathe big enough to allow that. I just know that this does not work well on a little lathe like my Sherline; I have not tried it on tools for my larger lathe. On the other hand, it might work for you, Carlo, so give it a try and let us know how it goes.

Oh, if you do get your belt sander up and running, Carlo, do yourself a favor. Build a good tool rest that can be set at precise angles and use a ceramic glass platen under the belt. The glass is sold by knifemaking suppliers and is called Pyroceram. It will stay flat for many years and is worth the low cost.


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## Doubleeboy

I quit fooling around with hand ground chip breakers a while back.  Yes , I could get one to work, but it made later sharpening problematic and did not seem worth the trouble.  Like Mike said, you can interrupt the cut periodically.  While not something I would do for a fine finishing cut, it works great while roughing.  Considering how small the chips are when taking a finish cut, even if it goes continuous I just pull it away with a hook tool.  If you have the room a vertical shear tool will make a great finishing tool and swarf is basically miniature steel wool.  Anyone can grind a shear tool, there are several you tube videos I believe, and its been written about on most of the machinist boards.

cheers
michael


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## Strtspdlx

Well the belt sander idea was a flop. I remembered it being a lot nicer looking. It doesn't have a belt and the motor wiring was cut all the way into the case. That and the person that was supposed to give it to me decided to not do so now. 
Anyhow I was taking a .040 cut on my lathe and I realized if I didn't make the cutting edge so long I may be able to use the unground part of the tool as a breaker of sorts. I'm going to attempt to grind a new tool and see if it may work. These long stringy chips keep throwing little chips and whatnot everywhere. And they aren't very fun to clean up. 


Regards-Carlo


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## Joe Pitz

Hi All,  Here is another cool video from Tom Lipton on tool grinding and chip control.
He grinds a tool very close to how Mikey would grind it, but with less side/edge relief.  But he does grind a fair amount of back rake.

Using a 1/2" tool he very easily turns steel at .875 DOC, at .005 and .010 feed rates.

Pretty amazing video using just HSS tool blank.






Thanks 

Joe


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