# How To Grind A Hss Turning Tool



## mikey

​
*This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear.*

Lathe tools are some of the most misunderstood and under-appreciated tools in the shop. The tip geometry on a HSS tool is hard to visualize, let alone understand, and grinding them accurately is even more confusing. It’s no surprise that so many hobby guys go to carbide tools, HSS insert tools or tangential tools – HSS tools can seem to take too much work.

Now here’s the reality: grinding lathe tools is actually really simple. You’re just grinding three flats at the tip of the tool, that’s all. Yeah, they’re all angled and they have confusing names but they’re still just flats. The cool thing is that even when you modify your tool geometry the grinding process is the same – 3 flats - it really isn’t any harder than that. And I'm going to attempt to show you how.

To grind a tool you need a good grinder; either a bench grinder or belt sander will do. I prefer the latter because it is easier for me to use and it cuts much cooler and much faster but I can use a wheel just as well. Your grinding media should be a coarse grit. I prefer a 24 grit Aluminum Oxide belt. I use some stick wax applied lightly to the belt before grinding each face.

Once the tool is shaped, I typically follow up with a 80 grit belt to remove coarse grind marks before honing on a coarse, then fine, then extra-fine diamond stone.

Your grinder should have a good tool rest. Mine is steel and is quickly settable to precise and reproducible angles. A good rest is very important, especially if you need to modify your tool geometry because you may be making changes of only a few degrees and a good rest will allow you to do that quickly and precisely.

Another very important tool is a push block. Mine is a 7” long X 1-1/2” wide X ¾” thick piece of plywood. It allows me to push directly into the belt and if there is a “top tip” in tool grinding it is this: push straight into the belt or wheel. The tool may be angled but your line of force into the cutting media is straight into it, and the block allows you to do that. It also helps you to stabilize the tool bit and move it side to side.

Other than your safety equipment, that’s it. Okay, let’s get to grinding!

My order of operations is to typically grind the side face first, then the end and then the top. While there are no rules on the order to take I follow this sequence because each face serves as a reference for the next. After grinding the side, it serves as a reference for the angle of the end face. Grinding the end forms the tip of the tool, which is used to tell me when to stop the top grind. This makes it easier for me to plan and control things as I progress so this is the sequence I prefer to use.

I am going to grind a general purpose right hand turning tool with a modified tip geometry that is not optimized for any one material but will work for most stuff we cut in a hobby shop. All the tool angles are 15° - side and end relief and side and back rake – so I call it a Square Tool. It will have a 1/32” nose radius that will produce a very good finish on most materials.

The general process is the same for all turning tools since they will all have the same three flats. The specific angles may differ, depending on the desired geometry but you will grind them the same way.


​Shown above is my belt sander. The tool rest is set at 15° and will not move for this tool. Should I need to change an angle, the rest will precisely set it in just a few seconds. I also use a ceramic glass platen liner to provide a long-lasting flat surface for the belt to run on; you cannot grind a flat if the platen itself is dished. Of all the mods you can do to a belt sander this platen liner is THE most important one. These liners are available from knife making suppliers, often under the name Pyroceram.

​
This is our blank, a high quality 3/8” HSS bit from Japan. Initially, I suggest you practice on mild steel key stock from the hardware store and switch to HSS when you are confident in your ability to grind what you intend.

*The Side*
The first face to be ground is the side of the tool. I normally make the length of this face 1-1/2 to 2 times the size of the bit; in this case ~ ¾” long. For a general purpose tool I will angle the tool bit so that about 50-60% of the end of the tool is ground off when the side is done.

For illustrative purposes, I have drawn a line to show what I mean. It is useful for new guys to do this as it helps you to align your tool bit to the grinding media. As you get used to grinding you won’t need this line.


​To be very clear, as we grind the side we are grinding the *side cutting edge angle (*represented by the inked line*)* and the *side relief angle (*set by your table angle*)* at the same time. Don’t let the labels bother you; although you’re grinding a flat the result will be these angles.


​This is how it looks as I grind this side face. The push block is angled in the picture because I wasn’t paying attention when I took the picture but it is perpendicular to the platen in use. As I grind, my force is straight into the belt. You can see the ceramic glass platen liner in the picture above.

The inked line on the bit parallels the face of the belt. My left hand simply helps to move the tool back and forth across the entire surface of the belt. The block provides all the pressure straight into the belt to keep it cutting continuously and also aids in moving the bit side to side. As you grind, the tool will heat up; just dip it in cold water and move on. Now we just grind to the line, pushing into the belt and using its entire width to grind a flat even surface.

Below is the finished side face. To recap, we have created the side cutting edge angle by grinding along that line we drew on the top of the tool. We have also ground the side relief angle of 15° at the same time because that is what our tool rest was set to. If you want more or less relief angle on the tool then just change the tool rest angle … got it?


​*The End*
Now we will grind the end face of the tool. The angle it forms relative to the side edge is called the *end cutting edge angle* and the clearance angle under this end edge is called the *end relief angle*, which is set by the angle of the tool rest.

For most tools I recommend that the end relief angle be kept the same as the side relief angle; in this case, 15°. Just this alone will reduce cutting forces and cutting temperatures versus standard geometry and you give up very little in terms of strength.

Since this tool is a general purpose tool, meaning it can turn, face or finish, it must be able to cut into a shoulder and then be able to face out. To accomplish this we will make the end cutting edge angle less than 90° so it can access corners without rubbing. I normally set it at 80°, which is represented here by an inked line:


​The table angle remains at 15° and I set up like this:


​For the end, the push block is moved up near the tip to provide both lateral support and some force to move the bit back and forth across the belt. My other hand holds that black line parallel to the face of the belt and provides the cutting force into the belt and also moves the bit side to side. The end face cuts fast – just grind it to the line.


​We have now ground the majority of the tool angles. If this were a tool for brass/bronze all we would need is to hone it, put a nose radius on it and the tool would be ready for use. For our tool, however, we have the very important rake angles to grind next.
​*The Top*
The top of the tool houses the two most influential angles on a turning tool – the side rake and back rake angles. While they might seem hard to grind they are actually the easiest, as you will see.


​I normally make the depth of the top grind about 1 to 1-1/2 the dimension of the bit. Here, I have marked the side of the blank at ½” from the tip. I will line this up with the right edge of the belt to serve as a reference, as seen below.

My steel table will not provide adequate support for the tool on the right side of the belt so I have an auxiliary table that drops on top of my standard table that does have a support area. This auxiliary table has some angled lines scribed on its top that allows me to choose from a variety of angles. In this case, I am using the 15° line and the bit is brought to the belt without changing this angle. You can also ink a line on the tool rest, up near the belt to help you align if you need to. Once the bit is angled the inked line on the side of the tool bit is brought to the edge of the belt and the support block is brought into contact with the tool bit. I am now ready to grind the top rake angles but before I do that …

Note that the table angle sets the *side rake* angle; in this case, 15°. The angle I am holding the bit at as I feed it into the belt sets the *back rake*, also 15°. As I feed the tool into the belt I am cutting both rake angles at the same time.

Also note that if you use a belt sander you need to track the belt off the right side of the platen about 1/16” to avoid cutting the belt. This also creates a nice radius into the back rake.



​To grind the rake angles all you do is use the push block to push the bit straight into the belt (or your wheel) – that’s all, a straight push. You do not move side to side here.

I visually align the front edge of the push block with the flat face of the platen and just push straight into the belt while my other hand maintains the 15° tool angle. The block really helps to direct your force – I would use one if I were you.

To orient you, the top of the tool is facing the belt. The side cutting edge is facing up, the back of the tool is touching the table and the bottom of the tool contacts the push block. Due to the angle of the table the belt will start to cut at the right rear of the top surface of the bit and as you grind, the ground surface will approach the side cutting edge and cut into it; then it will approach the very tip of the tool. Your goal is to stop the grind at the exact moment it reaches the tip. How do you know when the grind is getting to the tip? Just pull the tool away from the belt and look, and you’ll see something like this:

​
You can see that I’ve got a ways to go yet. To resume grinding, re-establish your tool angle and push. The flat that is currently ground into the tool will register itself on the platen if your right hand is relaxed. Now just keep grinding and checking until the grind reaches the tip of the tool, then stop.

You’ll see this:

​
If you have done this right the grind will extend all the way to the tip and there will be a nice curve ground into the rear of the top face of the tool. The tip of the tool will also be at the same height as the shank of the tool.


​We are done … almost. I normally use an 80 grit belt to redo each of the faces on the tool to remove the coarse shaping marks. This makes honing much easier to do. For this tool, I did not have a fresh 80 grit belt and had to hone a lot more than I normally would. Anyway, hone each face of the tool and put a nose radius on it.

I usually form the nose radius with my diamond stones as it is easier for me to control the size and shape that way. I hone a tiny flat with my stone at the very tip, being careful to follow the angle of the tip of the tool so that the flat is even, top to bottom. Then I gently round the edges of the flat so it blends into the side and end faces. I normally use coarse, fine and then extra fine stones to hone with.

Your goal as you hone is to remove all grind marks. If you use the same stones I use you will achieve a near mirror finish on your tool and the tool will be razor sharp so be careful with it.

You should have this when you’re done:





​You now know how each of the tool angles in the typical textbook illustration is ground. Sorry if I took the mystery out of it for you.


​You also know how to change each of those angles to suit your needs – change the tool rest angle and the angle of your bit as you grind it. You can find these standard angles in any tool angle table on the net or Machinery’s Handbook. It is just as easy to grind a modified tool as it is to grind a standard tool and I hope this gives you the confidence to experiment.

Lots of guys think you need a jig of some kind to grind a good tool. As you can see, this is not true. In fact, jigs restrict your ability to alter your geometry and I personally think this is a deal breaker. The only instance I can think of where a jig is useful is for grinding threading tools.

Total actual grinding time for this tool was about 4 minutes. Honing takes a few more minutes. If you hone it after each use it will likely last you a decade or more and not require a re-grind so making one like it is a skill well worth learning. I hope this helps you to do just that.

Give tool grinding a go and remember … you’re just grinding three flats.


Mikey

Addendum: Here are some links that will provide more information on tool grinding:

http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander/
http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-2/#more-5888
http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-3/#more-5897
This was a fun discussion we had on the HM Forum:

http://hobby-machinist.com/threads/turning-tool-and-facing-tool-questions.36687/

​


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## mikey

I drafted the above sometime in September of last year but due to chronic laziness and honest busyness, I only just now put the final touches on it. There have been numerous discussions about tool grinding, carbide vs HSS and so on recently and that got me off my butt. It is my sincere hope that this helps someone get over the hump and learn to grind tools. Most of us don't own big, rigid, fast or powerful lathes. We own hobby lathes, typically in the 10-11" class with max speeds of 2500 rpm or so. For those lathes and smaller, HSS is usually the best tooling option and we can further modify those tools to enhance the performance of your lathes even more.

I hope this gives you a start.

Mikey


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## Bob Korves

Great post, Mike.  You put a lot of effort into it.  Hopefully this will get a bunch of H-M members interested in making and modifying their own tools and getting better results.


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## mikey

Thanks for the kind words, Bob. Wish I had kept some of my original efforts, just to keep things in perspective. We all start at the same place, right?


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## taycat

thanks for that a lot easier to understand than a lot of the books.
bookmarked so i can refer back to it.


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## thomas s

Thank you Mikey you made grinding a tool look easy.


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## Ed ke6bnl

very good explanation, I consider myself a newbie and your method is a lot like I discovered by accident


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## higgite

Good job, as always, Mikey.

Tom


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## kentuckyjim

Thanks for sharing! I thought this was too complicated for me to master in a reasonable length of time so I bought hss inserts.  I think I could have mastered your process. Too impatient to wait I guess but I just want to make parts not stuff to make parts. Now if I could just figure out  how to get a better finish


Sent from my iPhone using Tapatalk Pro


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## BriancCc

Thanks for your great post. This is a great set of instructions. Breaking it out to simple steps makes it manageable to learn. 

I just started grinding lathe tools about 5 days ago. I watched some videos, http://tomstechniques.com/ and some others. I went at it making a couple of turning tools and a facing tool. They didn't come out beautiful but they worked quite well. 

I followed Tom and others advice about skipping the back rake angle so the bit can be indefinitely resharpened.


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## wawoodman

Great post, thanks.

What grit belt did you use for the roughing? (If I missed it, I apologize!) Do you use any lube on the belt?


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## sanddan

I recently bought a large lot of tooling and got a box of HHS cutting bits with most of them pre-ground into many different shapes. They really point out the advantages to grinding your own bits. Thanks for your write up, it went along way to explaining the process.


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## mikey

thomas s said:


> Thank you Mikey you made grinding a tool look easy.



It is easy, Tom; give it a go and see. What is not so easy is to understand what each of those angles do and what happens when you change them - therein lies the magic! There is enough material in the references I listed to get you well on your way - good luck, and show us your results.


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## mikey

kentuckyjim said:


> Thanks for sharing! I thought this was too complicated for me to master in a reasonable length of time so I bought hss inserts.  I think I could have mastered your process. Too impatient to wait I guess but I just want to make parts not stuff to make parts. Now if I could just figure out  how to get a better finish
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk Pro



Jim, I think you'll find that grinding is simple once you know what to do and how to do it, and now you do. I also own AR Warner HSS tools and like them but do yourself a favor. Grind the tool I showed above and come to your own conclusions.


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## mikey

BriancCc said:


> Thanks for your great post. This is a great set of instructions. Breaking it out to simple steps makes it manageable to learn.
> 
> I just started grinding lathe tools about 5 days ago. I watched some videos, http://tomstechniques.com/ and some others. I went at it making a couple of turning tools and a facing tool. They didn't come out beautiful but they worked quite well.
> 
> I followed Tom and others advice about skipping the back rake angle so the bit can be indefinitely resharpened.



Brian, thanks for your kind words. 

I'm happy to see that you've at least started to grind your own tools. I remember that with only 5 days of effort, I turned a 2-1/2" long tool bit into a burnt 1-1/2" long bit with so many facets on it that it was hard to tell which one was the cutting edge so good for you!

I know that eliminating back rake is a favored thing to do by some well-known guys, and even some guys here on the HM forum. Invariably, they say this makes re-sharpening easier because it does. However, I highly recommend that you grind a tool with back rake to compare performance before you blindly follow their advice. Without getting too technical, back rake reduces shear plane length and this has a significant impact on reducing cutting forces. It also focuses those forces at the tip of the tool and this enhances finishes significantly. 

I have some tools in need of re-sharpening. They are all at or beyond a decade of regular use and all have back rake ground into them. They have, and continue to perform as well as they did on the day they were ground because I hone them regularly. For me, honing for a few seconds works better than re-grinding a tool to re-establish a cutting edge. Plus, I have the performance advantages that back rake provides.

Again, sort it out for yourself. Grind a tool with and without back rake and see. I'm guessing that you'll cut deeper without chattering and you'll finish finer.


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## mikey

wawoodman said:


> Great post, thanks.
> 
> What grit belt did you use for the roughing? (If I missed it, I apologize!) Do you use any lube on the belt?



Thank you!

I use a 24 grit AO belt to shape and an 80 grit AO belt to remove coarse grind marks. I use DoAll wax stick lubricant before grinding each face - just a little dab will do ya! The wax really cuts down on grinding temps and the belt lasts much longer.


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## BriancCc

mikey said:


> Again, sort it out for yourself. Grind a tool with and without back rake and see. I'm guessing that you'll cut deeper without chattering and you'll finish finer.



I was mostly happy that I succeeded in making tools that worked. Going from zero to steel flying off the tool felt like a solid success. Thanks for the advice to try a back rake, I will give it a go.


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## ddickey

I'm ready to give this a go. Now all I need is a grinder. Lol
So not really ready just looking forward to it.


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## Christian Poulsen

mikey said:


> I drafted the above sometime in September of last year but due to chronic laziness and honest busyness, I only just now put the final touches on it. There have been numerous discussions about tool grinding, carbide vs HSS and so on recently and that got me off my butt. It is my sincere hope that this helps someone get over the hump and learn to grind tools. Most of us don't own big, rigid, fast or powerful lathes. We own hobby lathes, typically in the 10-11" class with max speeds of 2500 rpm or so. For those lathes and smaller, HSS is usually the best tooling option and we can further modify those tools to enhance the performance of your lathes even more.
> 
> I hope this gives you a start.
> 
> Mikey


Great posts and step by step Mikey....Except dissing on carbide again for home lathes (except for big, rigid, powerful lathes)...which is BS
Smiley Face here!
....Without going back and copying and pasting all the carbide info. and grades I've posted...straight up: The "good" carbide is stronger, harder, tougher and stays sharper many times over HSS
But granted, a common belt sander won't work on carbide....


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## mikey

BriancCc said:


> I was mostly happy that I succeeded in making tools that worked. Going from zero to steel flying off the tool felt like a solid success. Thanks for the advice to try a back rake, I will give it a go.



Yup, nothing succeeds like success. I wish you all the best, Brian, and do post pics of your tools if you can.


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## mikey

Christian Poulsen said:


> Great posts and step by step Mikey....Except dissing on carbide again for home lathes (except for big, rigid, powerful lathes)...which is BS
> Smiley Face here!
> ....Without going back and copying and pasting all the carbide info. and grades I've posted...straight up: The "good" carbide is stronger, harder, tougher and stays sharper many times over HSS
> But granted, a common belt sander won't work on carbide....



I have to leave to run some errands right now but I'll respond to this when I get back.


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## Tozguy

I grind both HSS and carbide tools. 
For carbide it is recommended in some cases to put a 45 deg bevel on the cutting edge to give it more strength. This idea is counter-intuitive after taking pains to get the edge sharp in the first place. But I buy the concept knowing how brittle some carbide tools can be and how hard some workpieces can be.
My question is about whether this idea can sometimes apply to HSS tools. A razor sharp HSS tool might be great for softer metals, but for the harder materials, that can be cut with HSS, would there be any advantage to honing a slight bevel on the cutting edge?


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## mikey

Christian Poulsen said:


> Great posts and step by step Mikey....Except dissing on carbide again for home lathes (except for big, rigid, powerful lathes)...which is BS
> Smiley Face here!
> ....Without going back and copying and pasting all the carbide info. and grades I've posted...straight up: The "good" carbide is stronger, harder, tougher and stays sharper many times over HSS
> But granted, a common belt sander won't work on carbide....



Chris, this thread  is intended to help our newer members learn to grind a HSS tool. It is a skill well worth learning because it is a skill that is being lost. The industry has moved almost entirely to carbide tooling and almost nobody in a modern shop grinds HSS tools anymore. Who, then, will keep this skill going? Us hobby guys, that's who. For whatever reason we choose to use these tools, we have to grind them to use them and I wanted to give the newer guys a start. 

Why not start a thread of your own? I promise not to come in and label something you said as BS.


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## mikey

Tozguy said:


> My question is about whether this idea can sometimes apply to HSS tools. A razor sharp HSS tool might be great for softer metals, but for the harder materials, that can be cut with HSS, would there be any advantage to honing a slight bevel on the cutting edge?



Mike, I honestly don't know. I never honed a 45 degree bevel on a HSS tool. Maybe you can try it and let us know how it works. The hardest stuff I've cut with HSS is maybe 4140 and had no problems at all but there are much harder materials out there. Normally, cutting really hard stuff, or hard turning, is done with fast, rigid lathes using CBN inserts so that leave me out - my lathe isn't nearly fast enough or rigid enough. 

The tool I use for 1144 or 4140 has slightly increased relief angles to improve penetration and more side rake to get the heat out of the cut, while back rake is usually left at the recommended angle for improved strength. I hone the edge sharp and the tool cuts well. 

Which harder material(s) are you referring to?


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## Tozguy

The materials would be steels that are on the hard end of the range that HSS can handle (whatever that is).
It is a theoretical question because I don't have a turning project on the go. I have been roughing out some HSS tools with renewed interest, to have a variety of them on hand and be ready for 'anything'.

The Machinery's Handbook Pocket Companion has a section on grinding carbide tools. On p.229 it states ''....and it is good practice to bevel the edges of roughing tools at 45 degrees to leave a chamfer of 0.005 to 0.010 inch wide. This is done by hand honing and is done to prevent crumbling or flaking off at the edges when hard scale or heavy chip pressure is encountered.''  There is a bit of information in this book about grinding chip breakers on HSS tools but little else.

This idea of giving the edge a bit more strength at the expense of sharpness might also apply to HSS tools to some extent or maybe not. I know it applies to knives in that edge bevels will vary according to the use intended.

 A more experienced person than I am, reading this, might have already been there and done that and have some clues for me. It is hard for me to believe that this has not already been considered somewhere and that no one can tell me if I am on the wrong track (which is probably the case) or not.


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## BriancCc

Here is a facing tool that I ground that is the least embarrassing of the group. I did this off the rest. It was the third of the night.

On the subject of back rake, I forgot that I'm using a tool holder that holds it at a bit of an angle. 

(I had a difficult time getting a photo of this thing.)


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## mikey

Tozguy said:


> This idea of giving the edge a bit more strength at the expense of sharpness might also apply to HSS tools to some extent or maybe not. I know it applies to knives in that edge bevels will vary according to the use intended.



On a HSS tool, you can bolster edge strength by reducing the relief angles. This provides a greater amount of material under the main cutting edge, thereby increasing strength. This is a compromise because cutting forces increase as a result. With many harder materials or materials that can potentially work-harden, the key thing is to get the heat out of the cut as expeditiously as possible and on a HSS tool, that means increased side rake and possibly back rake if finishing potential is also important. 

For the really hard stuff, Rc55+, you won't be cutting that with HSS. You need CBN inserts, a rigid lathe and high speeds. 

I don't make knives but many woodworking tools have a standard bevel and also a micro-bevel. This provides a very sharp cutting edge but with more mass backing it for strength.


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## brino

Great post Mikey, Thanks!

I'll be referring to this one often.

-brino


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## llhots

Fantastic post... Thanks! Much to learn about here.


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## mikey

BriancCc said:


> View attachment 140589
> 
> Here is a facing tool that I ground that is the least embarrassing of the group. I did this off the rest. It was the third of the night.
> 
> On the subject of back rake, I forgot that I'm using a tool holder that holds it at a bit of an angle.
> 
> (I had a difficult time getting a photo of this thing.)



Brian, thank your posting a pic of your tool. This is exactly what I hoped to see - pics of tools. This allows us to provide suggestions for improving the tool if you are willing. What say you?

If you do want input, it helps to have pics that show the tool clearly. Look at the 4-shot series of the completed tool in my original post and take pics like that - that will be a big help.


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## mikey

Brino and llhots, thank you! Just basic info but hopefully it will help someone.


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## Christian Poulsen

I guess I'm not


mikey said:


> Chris, this thread  is intended to help our newer members learn to grind a HSS tool. It is a skill well worth learning because it is a skill that is being lost. The industry has moved almost entirely to carbide tooling and almost nobody in a modern shop grinds HSS tools anymore. Who, then, will keep this skill going? Us hobby guys, that's who. For whatever reason we choose to use these tools, we have to grind them to use them and I wanted to give the newer guys a start.
> 
> Why not start a thread of your own? I promise not to come in and label something you said as BS.


Sorry Mikey but I am just answering in rebuttal to what seems as anti carbide/misinformation on threads  I read ...
...and I also agree and like to see the grinding (sharpening) skill of cutters going onward;
...Sharpening carbide also does just that (Again;  I'm not talking about insert tooling in the home, hobby setting (But grabbing a handful from a bucket of dull or chipped throw aways can also be silver soldered to prehard or boring bars and sharpened...(and IMO; My take (experience) with carbide is also good for the beginner/novice and home machinist to know and consider...

...Again and granted; A diamond wheel (I prefer a 220 "face wheel") is the way to sharpen carbide (with a coarser (around 100) diamond wheel on a regular old 8" "snag grinder is the way to rough form one (if needed)...
...But then, with all the same info around here (for instance like you have also posted) on HSS cutter angles and experimentation as applied to different materials, one ends up with a superior cutter (many times longer lasting edge) for most materials (steels,...especially the tool steels) on any lathe (that isn't "slop city" lol)...
....Again; Some carbides aren't much better(**) for wear than HSS and some it behooves one to put a little more nose radius (chipping) for heavy and interupted cuts...
....(**)= again depending on grades (thangs' such as cobalt content, grain size, tonnage of press, hot (or not lol) isostatically pressed...and yada yada

...so with all that, I'll post this link again and notice the braised carbide cutter pics and illustrations (ground forms and angles) are very much the same as HSS:
https://www.google.com/search?q=car...X&ved=0ahUKEwjyqf3oydTQAhWhxVQKHZIDAyIQsAQIGg


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## Hukshawn

I honestly find I actually have better luck with ground tools over my carbide bits. I'm really going to use this post! 
I have a bunch of 3/8" hss tool blanks coming for Christmas with a bunch more qctp tool holders. 
I bought an old Kennedy style tool box off a retired machinist a while back and I've been using all his tooling. Resharpening the right tools to use. I want to grind a bunch of my own nice tools and get them set in dedicated tool holders for the qctp. Gonna be sweeeet. *bookmarked*


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## mikey

Chris, my intent was to help a new guy learn to grind a good tool, that's all. As near as I can tell, I provided no misinformation. Instead, I tried to provide information as  simply and accurately as I could. 

If you're somehow construing that this post is a debate that somehow warranted a "rebuttal" from you, tell me what I said that justified such a vigorous response from you. Maybe instead of pushing your own agenda here, why not start a new thread that states your position and then teach the guys how to do what you think they should do? I may not agree with your views but I'll be damned if I don't respect your right to have them. And as I said before, I will not come into your thread and disrespect you. 

I am not a pro machinist like you. I am a lowly hobby guy with only 25 years messing with metal so I'm still learning every day. I am also a Professional in my own field, with over 35 years of experience. In my world, professional conduct is somewhat different.


----------



## mikey

Hukshawn said:


> I honestly find I actually have better luck with ground tools over my carbide bits. I'm really going to use this post!
> I have a bunch of 3/8" hss tool blanks coming for Christmas with a bunch more qctp tool holders.
> I bought an old Kennedy style tool box off a retired machinist a while back and I've been using all his tooling. Resharpening the right tools to use. I want to grind a bunch of my own nice tools and get them set in dedicated tool holders for the qctp. Gonna be sweeeet. *bookmarked*



Like you and Sandan, I have a drawer full of those HSS tools ground by some old school machinist, too. Some of them have some really interesting shapes that I haven't seen before, including some negative rake tools with chipbreakers on them that cut surprisingly well.

Hukshawn, good luck with your grinding. No pressure but if you care to share how they went, I'm sure the guys would enjoy seeing them.


----------



## Hukshawn

Well Christmas is still a couple weeks away, but if I remember, I'd be more then happy to share.

Also, after reading this, i got thinking, and tinkering. I have a bench top 4x21 belt/disc sander in my wood shop I don't ever use with an adjustable compound table.... guess what's going to turn into a dedicated tool grinding machine...


----------



## Ozwelder

*Mikey,
you wrote

<This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear>
*
_While I agree with most of what you say I would feel wrong to let this go unchallenged._
Gloves of any type on rotating  Machinery- A BIG *NO NO*

After  nearly 50 years in the trade I have had to assist injured fools that wore gloves on grinders just too  many times.

This is from your own American OHSA.

https://pmpaspeakingofprecision.com/2014/08/13/gloves-and-grinders-unsafe-osha/

I would look at reducing the belt grit size as its far too coarse for anything but roughing. 

Ideally a 8'' wheel of about 120 grit gives a near razor finish to the cutting tool. Great for hand grinding drill bits-no drill doctor required.

Safety first for sure

Regards
Ozwelder


----------



## Dan_S

Ozwelder said:


> *Mikey,
> you wrote
> 
> <This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear>
> *
> _While I agree with most of what you say I would feel wrong to let this go unchallenged._
> Gloves of any type on rotating  Machinery- A BIG *NO NO*
> 
> After  nearly 50 years in the trade I have had to assist injured fools that wore gloves on grinders just too  many times.



I'd add that if the wheel comes apart, an apron isn't going to do anything to protect you.


----------



## mikey

Ozwelder said:


> *Mikey,
> you wrote
> 
> <This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear>
> *
> _While I agree with most of what you say I would feel wrong to let this go unchallenged._
> Gloves of any type on rotating  Machinery- A BIG *NO NO*
> 
> After  nearly 50 years in the trade I have had to assist injured fools that wore gloves on grinders just too  many times.
> 
> This is from your own American OHSA.
> 
> https://pmpaspeakingofprecision.com/2014/08/13/gloves-and-grinders-unsafe-osha/
> 
> I would look at reducing the belt grit size as its far too coarse for anything but roughing.
> 
> Ideally a 8'' wheel of about 120 grit gives a near razor finish to the cutting tool. Great for hand grinding drill bits-no drill doctor required.
> 
> Safety first for sure
> 
> Regards
> Ozwelder



Thank you for your input, Oz. Yes, I recognize the danger of using gloves around rotating machinery. I don't use gloves when working on a bench grinder but I do when using my belt sander. The reason is that when, not if, a belt snaps the tag end can cut you in an instant. I have a scar that taught me this lesson. I am careful to leave only a 1/16" gap between the belt and the table and I use a push block to distance my hands from the belt. When weighing the danger, I feel that doing it this way is an acceptable risk. You are correct, however, in raising this red flag and again, I thank you for making us all aware of it.

I also agree that a 24 grit belt is too coarse for anything but roughing but that is what I use it for, roughing the shape before refining it with an 80 grit belt. The 24 grit shapes the tool fast without requiring excess pressure while also keeping grinding temps down. I tried every grit before I settled on this one and found it to be the best compromise. If you note the straw brown color of the tool bit after a face is ground; that tells me the tool is only getting to somewhere in the high 400 degree range. This is very cool when shaping a bit. Moreover, it only takes me about 2 minutes to grind the side, about 10 seconds to grind the end and maybe 1-1/2 minutes to grind the top of the tool so the belt cuts fast and cool without requiring excess pressure that might bog down the little 1/2HP motor I have. 

You spotted the inherent danger of my approach and the fact that the belt I use is quite coarse. First time anyone has pointed these things out and I appreciate you doing so. While I accept those risks we need to be sure others are cognizant of them so again, thank you.


----------



## mikey

Dan_S said:


> I'd add that if the wheel comes apart, an apron isn't going to do anything to protect you.



Yup, that's one of the reasons why I don't use a wheel. The apron works great for catching a fragment of belt that slams into your chest, of that I'm sure. For those using a bench grinder, use your wheel guards and make sure your wheels are sound. An exploding wheel is not an experience I wish to ever have again.

Thanks, Dan.


----------



## Hukshawn

Dan_S said:


> I'd add that if the wheel comes apart, an apron isn't going to do anything to protect you.


Not a whole heck of a lot is going to protect you if the wheel comes apart.. I've tended to make a bit of a habit to stand just off to the side of the wheel. especially on the wire wheel. those little curly spears are deadly.


----------



## Tozguy

Oz,
I have developed a tendency to wear gloves more often for many things but certainly not bulky gloves when it is known to be a hazard. On the question of wearing gloves (or not) while grinding is there any allowance to be made for belt grinders versus wheel grinders? 

Also, does it depend on the style of glove? I wear blue nitrile gloves almost always when in my shop and don't see any danger to it. It is great to have the grip they provide for many operations, grinding included.

PS  Had not read Mikey's post when typing this.


----------



## 4GSR

Mikey,

Can I send you all of my HSS and let you sharpen it for me? 

Just kidding.  Nice post there, especially the shots of each grind.  Pictures say a lot.  I look at more pictures than reading!

Ken


----------



## Christian Poulsen

Christian Poulsen said:


> I guess I'm not
> 
> Sorry Mikey but I am just answering in rebuttal to what seems as anti carbide/misinformation on threads  I read ...
> ...and I also agree and like to see the grinding (sharpening) skill of cutters going onward;
> ...Sharpening carbide also does just that (Again;  I'm not talking about insert tooling in the home, hobby setting (But grabbing a handful from a bucket of dull or chipped throw aways can also be silver soldered to prehard or boring bars and sharpened...(and IMO; My take (experience) with carbide is also good for the beginner/novice and home machinist to know and consider...
> 
> ...Again and granted; A diamond wheel (I prefer a 220 "face wheel") is the way to sharpen carbide (with a coarser (around 100) diamond wheel on a regular old 8" "snag grinder is the way to rough form one (if needed)...
> ...But then, with all the same info around here (for instance like you have also posted) on HSS cutter angles and experimentation as applied to different materials, one ends up with a superior cutter (many times longer lasting edge) for most materials (steels,...especially the tool steels) on any lathe (that isn't "slop city" lol)...
> ....Again; Some carbides aren't much better(**) for wear than HSS and some it behooves one to put a little more nose radius (chipping) for heavy and interupted cuts...
> ....(**)= again depending on grades (thangs' such as cobalt content, grain size, tonnage of press, hot (or not lol) isostatically pressed...and yada yada
> 
> ...so with all that, I'll post this link again and notice the braised carbide cutter pics and illustrations (ground forms and angles) are very much the same as HSS:
> https://www.google.com/search?q=car...X&ved=0ahUKEwjyqf3oydTQAhWhxVQKHZIDAyIQsAQIGg





mikey said:


> Chris, my intent was to help a new guy learn to grind a good tool, that's all. As near as I can tell, I provided no misinformation. Instead, I tried to provide information as  simply and accurately as I could.
> 
> If you're somehow construing that this post is a debate that somehow warranted a "rebuttal" from you, tell me what I said that justified such a vigorous response from you. Maybe instead of pushing your own agenda here, why not start a new thread that states your position and then teach the guys how to do what you think they should do? I may not agree with your views but I'll be damned if I don't respect your right to have them. And as I said before, I will not come into your thread and disrespect you.
> 
> I am not a pro machinist like you. I am a lowly hobby guy with only 25 years messing with metal so I'm still learning every day. I am also a Professional in my own field, with over 35 years of experience. In my world, professional conduct is somewhat different.


Mikey, I in no way think of anybody here as lowly....also I am not pushing my own or any agenda (In this subject case: Carbide as compared to HSS cutters)...
...But to answer how/and what that I construed a rebuttal (Which IMO is not so vigorous (I'm just also trying to teach and yes, no matter what experience we have, we all learn if we're open to it)...anyway, it is from a snippet from your subject somewhere above: "Most of us don't own big, rigid, fast or powerful lathes. We own hobby lathes, typically in the 10-11" class with max speeds of 2500 rpm or so. For those lathes and smaller, HSS is usually the best tooling option......"

...I guess so as not go round and round with examples and facts on your take again that carbide needs big, rigid, fast and powerful lathes that run more than 2500 RPM  I will use your own words in previous threads: "We should agree to disagree"... (But note: I don't think I have ever ran a manual machine spindle at more than 2000 rpm except for high speed polishing and  maybe for double o and triple 0 center drills, tiny drills and even then 1000 to 2000 depending on yada is norm)
...and again; My garage Logan, or the Machinists "old" 9" to 12" lathe area in our shop (Lablonde, Logan, Southbend and a pretty weak newer Clausing), although well kept, were anything but big, rigid, fast and powerful... 

...I also think, in regards to your dis on my professionalism above, I thinks' (Hey" I heard that!), maybe (probably) it's a difference in perception plus what environment each of us has worked in for decades, as in my world one cannot help but develop layers of thick skin on the shop floor...

...also please note that every comment I have given you respect by way of saying: "with all due respect but I disagree"...and, like on your subject title here: " Great posts and step by step Mikey except...." And note that my disagreements (just carbide details and applications so far) are just that and usually include a "smiley face here"

...also I'm the 1st one to admit while using "production value" as the buzz words I've seen here on this site regarding authoring my own subject titles;
 I would/am in last place as my only equipment in that regard is my "specs" and this laptop I'm pecking on now (again, even my phone is a $39.95 flip phone LOL)...
...so I'll just leave all the great "threads", questions, with pictures and videos to others and my silence usually means I'm learning or agree but when I see or read a detail that is off kilter I will respond with my opinion (and yes when the "off kilter" is somewhat repetitive, my response may include a "BS" (but followed with a "Smiley face here!")

...Maybe I need to work on my professionalism and friendliness  and just read (unless I see or read something dangerous).... I'm sure all will get along fine without my input)
https://www.linkedin.com/in/christian-poulsen-49b05b30?trk=nav_responsive_tab_profile


----------



## mikey

4gsr said:


> Mikey,
> 
> Can I send you all of my HSS and let you sharpen it for me?
> 
> Just kidding.  Nice post there, especially the shots of each grind.  Pictures say a lot.  I look at more pictures than reading!
> 
> Ken



Thanks, Ken. Coming from you, that's high praise.


----------



## mikey

Chris, as tempting as it is to respond to you honestly, I won't do that. Instead, I want to steer the discussion back to the subject at hand so that the new guys can ask questions and/or discuss their concerns. *This thread is about how to grind a tool and to help those who wish it.* This is about them. If you want to help them or if you have something to contribute to that subject then feel free to join the discussion. I, for one, would like to see what your HSS tools look like.

On the other hand, if you want to show us how to grind carbide tools then start a thread and show us how to do it. I'm willing to learn and I'm sure there are others here who would, too.


----------



## Hukshawn

What a beautiful tool... doesn't quite look like yours, but most the geometry is there. the cut is incredible. smoothest cut I've gotten so far. 
And the chips are the little curled up balls. 
Awesome


----------



## Hukshawn

What's the speed of that belt sander you have? 
I modified a 4x36" woodworking sander (just moved the table from the disc to the belt) set to 15°. 
Also, what belts do you use? I tried a home depot special, Diablo belt, says good for wood, metal, plastic. got about 5 minutes and that one tool bit out of it. now it's dull. lol


----------



## mikey

If the tool works then it works - good for you! As you get used to the process things will be easier to control - it looks like you're most of the way there already. I can see side rake, back rake, good relief angles and enough of an end cutting edge angle to access shoulders. Nose radius looks to be about 1/64" and that will work great. Pretty tools are great and will come with practice but function is what counts and you've got that now - way to go!

My belt sander runs at 3450 rpm. I get my Aluminum Oxide belts from an ebay seller called Barbkat. Most sanding belts have a shelf life of about a year so buy only what you can use quickly. If the belts get old the adhesive in the splice gives out and the belts can snap. I usually buy 5 belts of 24 grit to shape and 80 grit to fine sand the bit and then hone from there. I try to make tools in batches and grind up a bunch to use the belts while the splice is strong. Last time I ground tools I think I made 10 of them. Then I don't buy belts until I need to grind again. 

I also use a wax stick lubricant, applying some to the running belt for about 2 seconds. This is enough to cut cool and fast. I apply some before grinding each face. You can find this stuff on Amazon or from industrial suppliers. 

https://www.amazon.com/C-R-Laurence...480724066&sr=8-2&keywords=wax+stick+lubricant

One tube will last me over 10 years so its pretty cheap if you amortize it over time.


----------



## AR. Hillbilly

I have nothing to add but a thank you. I recently bought (5) 3/8" HSS blanks to get started on. I've tried some carbide and it worked ok but not a very good finish. I'm very new at this and like to run the lathe as slow as possible until I get a better feel for it. It had one HSS bit when I got it. I used it a few times and got a nice finish and then switched to carbide and could cut deeper but the finish wasn't as good. I feel like rpm is the main reason for that. I havea 6" and 8" bench grinders. I'm making some nice tool rests for the 6" and plan to use it for nothing but sharpening.
Your pics and descriptions were good. I really appreciate you sharing your time on this. That's why I like this place so much.


----------



## mikey

AR. Hillbilly said:


> I have nothing to add but a thank you. I recently bought (5) 3/8" HSS blanks to get started on. I've tried some carbide and it worked ok but not a very good finish. I'm very new at this and like to run the lathe as slow as possible until I get a better feel for it. It had one HSS bit when I got it. I used it a few times and got a nice finish and then switched to carbide and could cut deeper but the finish wasn't as good. I feel like rpm is the main reason for that. I havea 6" and 8" bench grinders. I'm making some nice tool rests for the 6" and plan to use it for nothing but sharpening.
> Your pics and descriptions were good. I really appreciate you sharing your time on this. That's why I like this place so much.



You're welcome. When you get that grinder set up, try making the tool I showed. It is a modified tool that will cut most common stuff while lowering cutting forces and cutting temperatures. If you reproduce it, it should rough well, size accurately and finish nicely. And you won't have to change your tool rest angle to make it.

Cutting speeds as we usually calculate them are starting points. Quite often, we need to adjust the speed to get the depth of cut we need (slower) or the finish we want (faster speed and/or slower feed). A good tool like that shown in the OP will let you cut deeper at higher speeds and will finish well at lower speeds due to the increased back rake. Give it a try and share it with us if you care to.


----------



## Bob Korves

sanddan said:


> I recently bought a large lot of tooling and got a box of HHS cutting bits with most of them pre-ground into many different shapes. They really point out the advantages to grinding your own bits. Thanks for your write up, it went along way to explaining the process.


It seems like every lot of old tools I get has a pile of already ground HSS tools that come as part of the deal, and also some NOS high quality HSS blanks as well.   I clean them up, and then sort them into categories -- RH turning, LH turning, L & R facing, form tools, internal tools, blanks, and so forth.   After cleaning and sorting them, I put them away by category, but first I give each one a close inspection to see how it was made and to speculate on what kind of material and job it was was ground to cut.  If only those old tools could talk...  Or if I could talk to the guys who ground them...  Many of them are very carefully made, with obviously lots of time and effort invested into making them.  Some were done on surface grinders or tool and cutter grinders, most by hand.  I have so many that I almost never need to make tools from blanks, though I have plenty of those as well.  I just find one that will do the job, or modify one that is close to doing the job, change relief and rake angles if needed, and make sure it is sharp.  It takes far less time than making a tool from scratch, and just about all the tools I have were obviously made by talented machinists.

I got those tools for less than scrap value.  They are useful, and work well after picking out the best one for the job and often making slight modifications.  I also have carbide insert tooling, and I use that as well, it is tougher and can take higher feeds and speeds.  It is also in dedicated holders, which makes them quick to get into play.  The old HSS tools are usually the go to choice when I am doing more than simple turning or facing.  Part of that is I want to see how the old tool made by someone who is now likely gone actually works, and honor his legacy.  If only those tools could talk...

Most of the tools I make myself from HSS are fairly simple, no back rake, smaller side and front angles than what Mike is showing, often with chip breakers ground in, but then my lathe is bigger and more rigid (13x40) than many H-M guys have.  Most of the HSS tools I come into are ground with angles more like Mike's work, and they work fine, but I do not push them hard.

I would feel quite limited with the few styles of holders and carbide inserts I have on hand, but they do the job for high removal rates and for harder and tougher materials.  My HSS tooling fills in for the "other" work...

Thanks again for the great thread, Mike!


----------



## Hukshawn

mikey said:


> If the tool works then it works - good for you! As you get used to the process things will be easier to control - it looks like you're most of the way there already. I can see side rake, back rake, good relief angles and enough of an end cutting edge angle to access shoulders. Nose radius looks to be about 1/64" and that will work great. Pretty tools are great and will come with practice but function is what counts and you've got that now - way to go!



the picture doesnt show it, but all of the angles you described in the first post are there. its a 3/8 tool, and i just didnt go as steep as you did. there is a good enough cutting angle to get into the shoulders. the top cutting surface is a mess because i dont have a very good edge to grind against. im using a pretty standard 4x36" belt/disc woodworking sander. i actually had to do that top cutting surface on the grinder. ive been keeping my eye out for a reasonable 1" belt sander.  i like this bit now, i may refine it, make the angles a bit steeper to get into tighter spots without having to constantly readjust the QCTP. 



mikey said:


> My belt sander runs at 3450 rpm. I get my Aluminum Oxide belts from an ebay seller called Barbkat. Most sanding belts have a shelf life of about a year so buy only what you can use quickly. If the belts get old the adhesive in the splice gives out and the belts can snap. I usually buy 5 belts of 24 grit to shape and 80 grit to fine sand the bit and then hone from there. I try to make tools in batches and grind up a bunch to use the belts while the splice is strong. Last time I ground tools I think I made 10 of them. Then I don't buy belts until I need to grind again.



im surprised, i would have assumed some other belt material other than aluminum oxide, it tends to dull faster than others. especially on tool steel. 
i deal a lot with sanding belts, but with wood. my stroke sander in my basement shop is 6"x168". and the drum sander is something like a 10' piece of 3". cant say ive ever had one snap. 

if youre able. im interested in seeing some other types of common tools youve ground for various uses.


----------



## mikey

Thank YOU, Bob. It helps for the guys to know how other experienced machinists make their tools. The more we share, the better it gets for all of us who use them.


----------



## mikey

Hukshawn said:


> the picture doesnt show it, but all of the angles you described in the first post are there. its a 3/8 tool, and i just didnt go as steep as you did. there is a good enough cutting angle to get into the shoulders. the top cutting surface is a mess because i dont have a very good edge to grind against. im using a pretty standard 4x36" belt/disc woodworking sander. i actually had to do that top cutting surface on the grinder. ive been keeping my eye out for a reasonable 1" belt sander.  i like this bit now, i may refine it, make the angles a bit steeper to get into tighter spots without having to constantly readjust the QCTP.
> 
> 
> 
> im surprised, i would have assumed some other belt material other than aluminum oxide, it tends to dull faster than others. especially on tool steel.
> i deal a lot with sanding belts, but with wood. my stroke sander in my basement shop is 6"x168". and the drum sander is something like a 10' piece of 3". cant say ive ever had one snap.
> 
> if youre able. im interested in seeing some other types of common tools youve ground for various uses.



This is the first of many, Hukshawn, and in time your tools will look exactly the way you want them to. The main thing is that they cut well for you. 

When looking for a belt sander, see if you can find one that uses a 2" belt and has a solid but replaceable platen so you can add a glass liner to it. It needs to be at least 1/2HP to grind tools. I would avoid the typical 1" sanders because the platen is usually mounted only on one end and WILL move when you apply pressure to it. Aluminum Oxide belts work great on my sander. I can get maybe 3 - 4 tools fully ground before I have to change the belt. Maybe the wax stick lubricant has something to do with extending belt life; I think so anyway.

The Square tool is just one tool. It is ground with angles that I found to work with most stuff - steel, tool steel, stainless, aluminum, and plastics. It also cuts brass like butter, even though the top rake angles are there. I came up with this tool after literally hundreds of experimental tools and it has proven to be a very good general purpose tool, at least good enough that I decided to share it on this forum. 

My personal tools look very much like this one. If I showed pics they would look the same because the angles are the main thing that differentiate them and you cannot see a 2-3 degree angle change in a pic. I did show some of them here: http://hobby-machinist.com/threads/turning-tool-and-facing-tool-questions.36687/. See post 153 and you'll see three pics; a knife tool, a tool steel cutter and my aluminum cutter. The first two were very old tools and the last was a few months old; have a look.

I can tell you that each tool works very well. 

My knife tool will put a mirror finish on any face I use it on and will also produce whisper-thin cuts on thin work pieces with very little deflection. It is one of my favorite tools and if you need a facing tool I highly recommend you consider making one. The one shown is for softer stuff; I also have one for hard stuff. They have replaced all the facing tools in my drawer. The details for construction are in the third part of the article from MachinstBlog I posted earlier. 
My tool steel cutter can take a 0.200" deep cut (0.400" reduction in diameter) in 1144 semi-hardened steel on my 11" Emco lathe, and then take a 0.001" deep sizing cut and produce a fine finish. That's a healthy cut in semi-hardened steel and the lathe doesn't even slow down. I mention this because I initially made this tool to work on my little Sherline lathe, where it takes a 0.04" deep cut in 1144. That may not seem like a deep cut but on a lathe as small as a Sherline it is very good. It will also take a 0.050" deep cut (0.1 reduction in diameter) in mild steel while leaving a pretty good finish on the part. 
This tool is ground with slightly increased relief and rake angles to reduce cutting forces and temperatures and most of the heat goes out with the chip. As a result, very little work hardening occurs so that very small sizing or finishing cuts can be taken after the work is roughed in. A tool ground to the angles found in a typical angle table will not be nearly as capable of doing this.​
My aluminum cutter looks weird because the belt was being displaced on the platen due to the extreme back rake angles I use. I found out that the reason the belt moves is because the tensioning spring on my belt sander is weakening after all these years so the belt can move. I haven't been able to track down a replacement yet as this grinder is out of production. Anyway, this tool will take a 3/8" deep cut in aluminum and then produce a mirror-finished fine cut on the part. Due to the increased relief and rake angles, the tool cuts with little force and has not ever developed a built up edge. 

One tool I didn't include in that post was a roughing tool for mild steels. This guy is a workhorse. I haven't pushed it to see what it can do but I have taken a 0.200" deep cut in 12L14 with it and it cut without a whimper. Tool angles are standard except for slightly increased side and back rake angles to reduce cutting forces and temperatures while still retaining strength under the cutting edge. It looks like the pic despite being about 10+ years old. Anytime I need to turn mild steel, this is the tool I use. It was intended to be a roughing tool but it sizes and finishes like a general purpose tool - pretty useful. 

​
My tools are just everyday tools like yours, except that they have all been modified to reduce cutting forces and temperatures and improve penetration. None are ground to the angles in a grinding table. When I say that they reduce cutting forces, this translates into extending the limits of the lathe. A very small lathe, like a Taig or Sherline, will double its cutting capacity before running into chatter issues with these tools. When I say you should consider modifying your tools (and there is enough info in the links provided in the OP), I wasn't kidding.


----------



## Bob Korves

Hukshawn said:


> (snip)ive been keeping my eye out for a reasonable 1" belt sander.(snip)


Harbor Freight (Princess Auto?) has a very cheap one that does the job OK.  Get the one without the disc sander, belt sander only...

Edit:  I see Mike does not like the cheap HF 1" grinder, and I understand why.  He is using it to do roughing work while I will only use it for touch ups and finishing.  It is pretty worthless for hogging anything, and yes, the platen is soft.  I have not had the luxury of ever using a powerful narrow belt sander...


----------



## Bob Korves

mikey said:


> Thank YOU, Bob. It helps for the guys to know how other experienced machinists make their tools. The more we share, the better it gets for all of us who use them.


Knowledgeable, perhaps, but experienced, not so much...  Just an old codger playing with machines for fun.  I had a lot of exposure to metal working in the work I did for 40 years, so some of it comes through osmosis, but actually doing the work is another thing altogether.  You can watch a million YouTube videos. but will not learn many of the important details and work flow choices until you have your hands on the controls enough times.  That said, I have no idea how hobby machinists learned enough in the old days before the internet and YouTube (and Hobby-Machinist!) and other sources available today to keep from hurting themselves.  Machining is not really something you can learn from a book, without some hands on coaching and mentoring to get you safely started down the right paths.  Making tools is one of those skills.  I would never show my first attempt at making a HSS tool...


----------



## mikey

Bob Korves said:


> Knowledgeable, perhaps, but experienced, not so much...  Just an old codger playing with machines for fun.  I had a lot of exposure to metal working in the work I did for 40 years, so some of it comes through osmosis, but actually doing the work is another thing altogether.  You can watch a million YouTube videos. but will not learn many of the important details and work flow choices until you have your hands on the controls enough times.  That said, I have no idea how hobby machinists learned enough in the old days before the internet and YouTube (and Hobby-Machinist!) and other sources available today to keep from hurting themselves.  Machining is not really something you can learn from a book, without some hands on coaching and mentoring to get you safely started down the right paths.  Making tools is one of those skills.  I would never show my first attempt at making a HSS tool...



Regardless of what you say, Bob, you have my respect. You have helped me and many others here on HM and you've earned it.

Yup, I'm one of those old goats that started messing with tool geometry before there was an Internet. I've mangled many a tool bit, I can tell you that! Heck, I went to college when the newest high tech thing was a room-sized computer that used key punch cards.


----------



## AR. Hillbilly

mikey said:


> You're welcome. When you get that grinder set up, try making the tool I showed. It is a modified tool that will cut most common stuff while lowering cutting forces and cutting temperatures. If you reproduce it, it should rough well, size accurately and finish nicely. And you won't have to change your tool rest angle to make it.
> 
> Cutting speeds as we usually calculate them are starting points. Quite often, we need to adjust the speed to get the depth of cut we need (slower) or the finish we want (faster speed and/or slower feed). A good tool like that shown in the OP will let you cut deeper at higher speeds and will finish well at lower speeds due to the increased back rake. Give it a try and share it with us if you care to.


Will do. It may be a spell. I haven't finished the rests on the grinder yet. The grinder works well but the  original rests are flimsy junk. These will be fairly large and very rigid rests with easy adjustment.
My work has kept me fairly busy lately and the dear wife wants some kitchen repairs done before I get much more shop time.


----------



## mikey

Happy wife, happy life - her first.

We'll be here when you have the time.


----------



## Hukshawn

What kind of aluminum oxide belts are you using? I went shopping today. got a wax stick, different brand, meant for threads or grinding etc, but looks like the right stuff. got a new 40 grit belt and a couple discs. I can grind about half a face using about 1/3 of the 4" belt. I get half a face ground and the belt is dull. 
I'm trying to grind a 3/8 hss tool bit, pictured below... 
Is this bit super hard? even my grinder is having a hard time. I like these 3/8" bits. the 1/4" ones I have seem to grind nicer...
What am I doing wrong here...


----------



## mikey

The name on the belt is "Deerfos XA617+". Not sure why your belt aren't lasting - maybe the platen? My grinding times are with a 24 grit belt. I am putting about half the force needed on a bench grinder but there is force. Be sure your platen is not flexing as you apply pressure.

3/8" bits are much harder to grind than 1/4" bits - takes about twice as long to grind. What you have there is a *T15 *cobalt bit, which is even harder to grind - takes about twice as long to grind as a 3/8" M2 HSS bit. That bit will hold an edge for a long time and will cut harder steels but for most stuff you will turn, M2 is sufficient and easier to work with.

I have two suggestions. First, buy some M2 bits. Second, buy some 3/8" mild steel square key stock from the hardware store and practice with that first. When your practice tools look the way you want and you're clear on how to move your hands, etc, then move to the M2 bits. When those come out good, then go to cobalt.

By the way, what kind of lathe are you using and what is the top speed you can get on it?


----------



## Hukshawn

I was wondering if it was harder... that was a nice uncut piece I had in my tool box. So I wanted to try to make a nice new bit. Others that had been previously gerund do grind better. The pieces I have coming are just standered hss. I don't think I'm too concerned with the mild steel practice. I was just dwelling on that one piece. I'm other words, it was kicking my ass... 
I have another piece of 3/8 that ground nicer when I tried it, but then I got yelled at cause the noise woke the kiddo. Haha.

I have an enterprise 10 lathe. Check out "crazy threads" in the questions forum. It pretty well dovers all aspects of my lathe but it has a posted top speed of 2000 rpm. But I do most of my work in the 500-1000 range. Actually. I don't think I've ever even ran it at 2000. It would probably scare me half to death.


----------



## mikey

Okay, yeah, the M2 will be easier to work with at this stage. Oh, by the way, I had a good laugh as I pictured your face grinding that cobalt tool ... WTF!!??

I wouldn't be too afraid of higher speeds. The softer the material (aluminum, brass) the faster you can go. I usually turn aluminum at around 2800 rpm with HSS. Harder stuff and deeper cuts require slower speeds.


----------



## Hukshawn

ill try the higher speeds. Just get it over with and learn. 

What's the proper way to grind those harder tools? Specific wheels? Belts? Diamond?


----------



## Hukshawn

I think I'm comfortable the slower speeds because my lathe can handle it better. Last time I used the high belt positions the lathe hogged down a bit. 3/4 hp motor.


----------



## mikey

Hukshawn said:


> ill try the higher speeds. Just get it over with and learn.
> 
> What's the proper way to grind those harder tools? Specific wheels? Belts? Diamond?



Use whatever speed works. My tools allow me to go faster.

I use the same belt sander to grind cobalt. It just takes me a little longer.


----------



## mikey

Hukshawn said:


> I think I'm comfortable the slower speeds because my lathe can handle it better. Last time I used the high belt positions the lathe hogged down a bit. 3/4 hp motor.



Oh, yeah, a 3/4HP motor might be an issue. My lathe has a 2HP motor on it. This is all the more reason to learn to grind tools - they will enable you to do a lot more with the power you do have. 

I truly hope this turns out to be a worthwhile endeavor for you, Hukshawn.


----------



## Dan_S

Since It's on topic I thought i'd share this, special thread relief tool I made last week from a 3/8" square blank. The short end is .030" wide, and the long one is 0.045". Each end took about 5 minutes on my grinder using a CBN wheel. You can't see it in the picture but the short end is actually at an angle to the blank so that I could get the clearance need to clear a large shoulder.


----------



## mikey

Whoa, Dan, that is awesome! Super-clean grind done with skill! Did it work as good as it looks?

I've been wondering how good a CBN wheel grinds HSS lathe tools. They're expensive so I was waiting for someone like you to report on it. Can I ask which wheel you're using? Is the corner of the wheel sharp or radiused? What grit works best for shaping and/or finishing?

Have you ground any turning tools with this wheel? I'd sure like to see some pics if you have them. No pressure, Dan, really but I just have a good friend that prefers a bench grinder and I've told him to look into CBN wheels and I think he, and others, would like to see the results.


----------



## Hukshawn

Here's that doAll bit that was kicking my ass... I was bound and bent to finish it... and from what you said about it's longevity, I wanted to use it. 
critique it, and go!
The cut is pretty damn good. like butter. and I cranked the lathe up to 1400 rpm. seems I need to do some belt tightening in high gear tho


----------



## higgite

Dan,

Those are great looking tools. I have a CBN wheel that I got when I was grinding my own tools when I first got a mini lathe, then I got lazy and asked Santa for some HSS insert tools. But, you have given me some inspiration to crank up the grinder again and grind a thread relief tool or two. Of course, then I'll have to make a new QC tool holder... or two. Which means I need to ask Santa for a dovetail end mill... or two. Which means....
Jeez, a lazy hobby machinist's work is never done.

Tom


----------



## BriancCc

Here is the tool I ground and a block I faced with it. I'm open to advice. I'm using a 6" bench grinder with 48 grit wheel. I did this off the tool rest. I'm using this on a Clausing 100 with a lantern tool post. I'm using a armstrong holder, which holds it at like a 8deg angle.  So that is like, the work angle is 8deg added to tool back rake, and work angle is 8deg less front clearance than tool angle, right?


----------



## Dan_S

mikey said:


> Whoa, Dan, that is awesome! Super-clean grind done with skill! Did it work as good as it looks?



O yea, it work great



mikey said:


> . Can I ask which wheel you're using? Is the corner of the wheel sharp or radiused? What grit works best for shaping and/or finishing?


Right now I'm using the 8" d-way 180 grit wheel.
http://d-waytools.com/cbn-wheel-8-x-1-1-2-x-1-arbor-hole/


It leaves an excellent surface finish right of the wheel that can quickly be honed. I plan to get the 80 grit wheel for the other side at some point, as it will remove material even faster.



mikey said:


> Have you ground any turning tools with this wheel? I'd sure like to see some pics if you have them.



I took photos of the two below this morning as I know for sure I ground them with it. I use mostly carbide now, so I only go to HSS for specialty stuff. The honing was done with a cheap diamond credit card hone.

large threading tool 3/8" shank.





vertical sheer tool 3/8" shank


----------



## Dan_S

higgite said:


> Dan,
> 
> Those are great looking tools. I have a CBN wheel that I got when I was grinding my own tools when I first got a mini lathe, then I got lazy and asked Santa for some HSS insert tools. But, you have given me some inspiration to crank up the grinder again and grind a thread relief tool or two. Of course, then I'll have to make a new QC tool holder... or two. Which means I need to ask Santa for a dovetail end mill... or two. Which means....
> Jeez, a lazy hobby machinist's work is never done.



Ask Santa for a shaper, then you can make the QC tool holder with a ground HSS bit.


----------



## mikey

Hukshawn said:


> Here's that doAll bit that was kicking my ass... I was bound and bent to finish it... and from what you said about it's longevity, I wanted to use it.
> critique it, and go!
> The cut is pretty damn good. like butter. and I cranked the lathe up to 1400 rpm. seems I need to do some belt tightening in high gear tho



Okay, you definitely know how to grind the rake angles and that is usually the hardest thing for guys to get a handle on. If the cut is good then that is what counts. With that said, I would suggest you grind your next tool with a bit more mass backing the tip. Use a protractor and draw a line at 80 degrees, using the side cutting edge as a base or reference. Once you grind to that line there will be more mass backing the tip for strength. 

Doing good, Hukshawn!


----------



## mikey

BriancCc said:


> Here is the tool I ground and a block I faced with it. I'm open to advice. I'm using a 6" bench grinder with 48 grit wheel. I did this off the tool rest. I'm using this on a Clausing 100 with a lantern tool post. I'm using a armstrong holder, which holds it at like a 8deg angle.  So that is like, the work angle is 8deg added to tool back rake, and work angle is 8deg less front clearance than tool angle, right?



Brian, thanks for the pics. It really helps to see the tool better.

The overall tool shape is fine for a facing tool. It is difficult to estimate side rake but it looks to be about 12 - 14 degrees to my eye and that's fine for steel. I make the front clearance angle somewhere around 22 degrees or so; minus the 8 degree tool angle, this gives you 14 degrees of clearance, which is great. There is very little nose radius; I can't see any but it could be my eyes. You have no back rake other than that provided by the tool holder angle so call that 8 degrees. 

This tool should face well. The only thing I would suggest is to try honing a little nose radius on the tool - it will give a better finish. A facing tool cuts mainly with the side cutting edge, up near the nose, but the nose does participate. Try honing a tiny nose radius and see what happens. 

You will find that a tool rest helps to control your angles, and it's safer, too. It will improve the finish on the tool because the tool isn't bouncing around as you grind. Honing the edges will also greatly improve the finish cut so if you prefer not to use a rest then hone to a clean edge. A sharp tool will cut curliques in paper with it's edge. 

You're doing great! Share with us as you progress, Brian!


----------



## mikey

Dan_S said:


> O yea, it work great
> 
> 
> Right now I'm using the 8" d-way 180 grit wheel.
> http://d-waytools.com/cbn-wheel-8-x-1-1-2-x-1-arbor-hole/
> 
> 
> It leaves an excellent surface finish right of the wheel that can quickly be honed. I plan to get the 80 grit wheel for the other side at some point, as it will remove material even faster.
> 
> 
> 
> I took photos of the two below this morning as I know for sure I ground them with it. I use mostly carbide now, so I only go to HSS for specialty stuff. The honing was done with a cheap diamond credit card hone.
> 
> large threading tool 3/8" shank.
> View attachment 140755
> 
> View attachment 140756
> 
> 
> vertical sheer tool 3/8" shank
> View attachment 140757
> 
> View attachment 140758



Thanks, Dan. So, 80 grit to shape ... got it. I'll make sure my friend sees this post.


----------



## Hukshawn

mikey said:


> Okay, you definitely know how to grind the rake angles and that is usually the hardest thing for guys to get a handle on. If the cut is good then that is what counts. With that said, I would suggest you grind your next tool with a bit more mass backing the tip. Use a protractor and draw a line at 80 degrees, using the side cutting edge as a base or reference. Once you grind to that line there will be more mass backing the tip for strength.
> 
> Doing good, Hukshawn!


Just to make sure I understand you, don't cut such a sharp angle on the right side of the cutting tip? let's call that right side face a 45° to the adjacent side. you'd like me to go as shallow at 80°. am I understanding correctly?


----------



## Hukshawn

All of these rake terms I read in the south bend - how to run a lathe book, are making much more sense now...


----------



## mikey

Hukshawn said:


> Just to make sure I understand you, don't cut such a sharp angle on the right side of the cutting tip? let's call that right side face a 45° to the adjacent side. you'd like me to go as shallow at 80°. am I understanding correctly?



Yes, exactly. If you take the side cutting edge and rotate it so it is vertical, then draw a line about 10 degrees below  horizontal and grind the end cutting edge angle to that line it will give you a lot more mass backing the tip so the tool can sustain heavier cuts. See the OP for grinding the second flat if this is not clear. 

A tool shaped like the above will take a cut as heavy as your lathe can handle without breaking the tip off.


----------



## Hukshawn

Got it! I will readjust.
You seem to like this tool for most general machining. how do you alter for various needs/materials? I think you mentioned previously all you do is change the rake angles. can you specify? and reasons. I'm actually learning a lot here.


----------



## mikey

I'm having trouble with my laptop. Hope this goes through.

This is a tool I share with others because it works for most things. I also use material-specific tools with the same general shape but with relief and rake angles that suit each material group. My stainless tool is different from my tool steel tool, etc. Each tool has relief and rake angles that are intended to reduce cutting forces or accommodate a characteristic of the material.

If you have time, read the articles I linked to in the original article. It will tell you what each angle on the tool does and how you can modify the tool to do what you want. For example, if you work with stainless steel you will find that it has a tendency to work harden due to high temps in the cut. Stainless likes more aggressive relief angles to cut well but if you also increase side and back rake the chip clearance is better. Since most of the heat in a cutting operation is in the chip, the faster you get the chips out the lower the cutting temps are and consequently the less work hardening occurs. In other words, you can use your tool angles to make the tool do what you want it to do.

Another example is aluminum, which tends to get hot when cut and then it gets "gummy" and can weld onto the tip of your tool. My tool has increased relief angles to penetrate faster and it has large (40 degrees!) rake angles to get the heat out of the work fast. As a result, I don't have any issues with chip welding. I also add more back rake and a more generous nose radius to improve finishing potential and my aluminum tool leaves a mirror finish, even on roughing cuts. This tool is amazing in aluminum.

The rationale for these tool angle changes is explained on page 5, post 137 of this thread:
http://hobby-machinist.com/threads/turning-tool-and-facing-tool-questions.36687/

As you learn how each material likes to be cut you will be able to adjust your tools to accommodate them. You just need to know what each angle does so you know what to change to get what you need.

Don't underestimate the value of cutting force reduction. You only have 3/4HP, which is not a lot of power. By prioritizing cutting force reduction your tools will enable your lathe to make cuts it may not be able to make with a standard tool. That is the beauty of HSS lathe tooling - you can modify it to extend your lathe's capabilities while enabling you to machine stuff more efficiently.


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## Hukshawn

I don't have a clear protractor, I have a machinists protractor/ruler, but that was cumbersome. so I winged it. but it's about 75°. but my back rake angle to the side is much steeper than I intended. I actually screwed up and flipped the bit over and did the other side...
But this is a hefty tool. lots of meat.


----------



## mikey

Yeah, you got it. Add a bit of nose radius and you should be good to go. That tool will now take a heavy cut without you worrying about the integrity of the tip. Have you tried it yet?


----------



## Hukshawn

Ya I didn't hone it or do the radius before I took the picture. It works well. I took a quick pass on whatever I had in the lathe. A 1" bar. With the angle I had the tool set in the QC it didn't leave as nice of a cut as the other bit,but it swollowed a 3/16" thick pass without killing the lathe. And I had it at 1400 rpm. Fast but not very strong. But by that point I only has 1/2" of marterial left after previous test passes. It distorted the thin piece but still cut well. So, I'm satisfied. I've really learned a lot about tooling here, mike. This was one portion of the hobby I was really trying to understamd and improve but just using reading material wasn't cutting it... so to speak... 
thanks for sure. 
Shawn


----------



## mikey

You're welcome, Shawn. You learn fast and I'm sure that in time tool grinding will come second nature to you. Keep us posted, okay?


----------



## schemer

Hey Mikey,
  Great informative thread on tool grinding. What I would like to know is, what brand/model belt sander is that you are using?
Thanks


----------



## mikey

schemer said:


> Hey Mikey,
> Great informative thread on tool grinding. What I would like to know is, what brand/model belt sander is that you are using?
> Thanks



Thank you!

I am using an old Craftsman 1/2HP 2 X 42" belt sander. I can't even remember when I bought this machine. Its over 15 years for sure, maybe more, and it is absolutely reliable. They are still available as a somewhat anemic 1/3HP version nowadays. I have one of these weaker sanders and I can completely stop the belt when grinding a tool so I cannot recommend it for tool grinding. They are sold by Palmgren, Dayton and others.

You would think that anything from Sears is basically junk but this is one of the more intelligently designed sanders for tool grinding. The reasons I say this is because the platen is easily replaced with a  piece of angle iron to which a piece of ground steel can be attached. To this, a glass liner can be adhered and the whole thing shifted back to allow the glass liner to run even with the front of the two wheels. The right side of the platen is entirely exposed; there is no sheet metal in the way, and this allows full access to the belt for grinding the rake angles on a tool. This access thing makes most belt sanders on the market (except for the 2 X 72's) unacceptable to me.

This sander also has a chassis that is flat so a template with holes to angle the tool rest is easy to attach. The tool rest is simple to fabricate and allows for angle changes in seconds without tools. If you're interested in more on this sander, see here: http://www.machinistblog.com/modifying-a-craftsman-2-x-42-inch-belt-sander-for-tool-grinding/

The belt tracking mechanism is simple and precise. It does not allow the belt to drift unless the tension spring gets weak and this is only an issue if you're grinding huge back rake angles. If you can't tell, I love this tool!

I've been looking for a replacement or substitute grinder for years and haven't found one that satisfies my needs. The two things I mentioned - ability to attach a platen and have the right side completely accessible and the ability to attach a tool rest template - are important to me. If anyone spots something like this, let us all know.


----------



## RonWB1957

Timing is every thing. I need to learn to grind my own HSS bits. I need to find out how to grind a bit for cutting the recess in a medallion. SO how do you guys grind the tip to allow clearance when cutting the recess? Is the tip still centered on the diameter ?


----------



## Dan_S

RonWB1957 said:


> Timing is every thing. I need to learn to grind my own HSS bits. I need to find out how to grind a bit for cutting the recess in a medallion. SO how do you guys grind the tip to allow clearance when cutting the recess? Is the tip still centered on the diameter ?



are you talking about cutting a grove into the face of a part?


----------



## mikey

Hey Ron,
I'm not clear on how the tool will be applied to a medallion or what recess you're referring to. Can you post a pic of the project set up in the lathe? Then we might have more useful input for you.

Thanks


----------



## Dan_S

mikey said:


> Hey Ron,
> I'm not clear on how the tool will be applied to a medallion or what recess you're referring to. Can you post a pic of the project set up in the lathe? Then we might have more useful input for you.
> 
> Thanks



I think he is talking about a trepanning tool, but I'm not 100%.


----------



## mikey

Oh, okay. Thanks, Dan. By the way, my friend who was looking at CBN wheels said to tell you that you do really nice work. I agree!

Let's see if he posts a pic.


----------



## Dan_S

mikey said:


> Oh, okay. Thanks, Dan. By the way, my friend who was looking at CBN wheels said to tell you that you do really nice work. I agree!
> 
> Let's see if he posts a pic.



Thanks man.


O and I knew this what out there some place. Keith Fenner making a trepanning tool.


----------



## RonWB1957

The second from the left shows what I need to do. IT allows to either be etched or an insert glued in. Thanks


----------



## mikey

Typically, trepanning leaves a remnant in the center - not the case here. It would be easier to cut it with a knife tool by spotting the center with a spotting drill to the depth of the hole, then turning from the center to the rim. In brass, this would be a shallow roughing cut and a skim finishing cut. The tip of the tool would be on center and the side cutting edge would parallel the ways to produce a square shoulder. 

A knife tool looks like this:


----------



## RonWB1957

Thank you. I now see what I was doing wrong. Not enough side clearance. The lower portion of the bit was hitting the side wall, leaving a chamfer.


----------



## mikey

RonWB1957 said:


> Thank you. I now see what I was doing wrong. Not enough side clearance. The lower portion of the bit was hitting the side wall, leaving a chamfer.



Yup, hope it turns out okay. If not, come on back.


----------



## Dan_S

Ron, what kind of saw are you making?


----------



## Sparkysparty

you could use a milling slot drill to plunge cut, they come in many different sizes mm and inches.


----------



## benmychree

mikey said:


> View attachment 140461
> ​
> *This is a discussion about tool grinding, which can be a dangerous business. I highly recommend safety glasses, leather gloves, dust mask and hearing protection. I also use an apron in case something comes apart and hits me. Please be careful and wear your safety gear.*
> 
> Lathe tools are some of the most misunderstood and under-appreciated tools in the shop. The tip geometry on a HSS tool is hard to visualize, let alone understand, and grinding them accurately is even more confusing. It’s no surprise that so many hobby guys go to carbide tools, HSS insert tools or tangential tools – HSS tools can seem to take too much work.
> 
> Now here’s the reality: grinding lathe tools is actually really simple. You’re just grinding three flats at the tip of the tool, that’s all. Yeah, they’re all angled and they have confusing names but they’re still just flats. The cool thing is that even when you modify your tool geometry the grinding process is the same – 3 flats - it really isn’t any harder than that. And I'm going to attempt to show you how.
> 
> To grind a tool you need a good grinder; either a bench grinder or belt sander will do. I prefer the latter because it is easier for me to use and it cuts much cooler and much faster but I can use a wheel just as well. Your grinding media should be a coarse grit. I prefer a 24 grit Aluminum Oxide belt. I use some stick wax applied lightly to the belt before grinding each face.
> 
> Once the tool is shaped, I typically follow up with a 80 grit belt to remove coarse grind marks before honing on a coarse, then fine, then extra-fine diamond stone.
> 
> Your grinder should have a good tool rest. Mine is steel and is quickly settable to precise and reproducible angles. A good rest is very important, especially if you need to modify your tool geometry because you may be making changes of only a few degrees and a good rest will allow you to do that quickly and precisely.
> 
> Another very important tool is a push block. Mine is a 7” long X 1-1/2” wide X ¾” thick piece of plywood. It allows me to push directly into the belt and if there is a “top tip” in tool grinding it is this: push straight into the belt or wheel. The tool may be angled but your line of force into the cutting media is straight into it, and the block allows you to do that. It also helps you to stabilize the tool bit and move it side to side.
> 
> Other than your safety equipment, that’s it. Okay, let’s get to grinding!
> 
> My order of operations is to typically grind the side face first, then the end and then the top. While there are no rules on the order to take I follow this sequence because each face serves as a reference for the next. After grinding the side, it serves as a reference for the angle of the end face. Grinding the end forms the tip of the tool, which is used to tell me when to stop the top grind. This makes it easier for me to plan and control things as I progress so this is the sequence I prefer to use.
> 
> I am going to grind a general purpose right hand turning tool with a modified tip geometry that is not optimized for any one material but will work for most stuff we cut in a hobby shop. All the tool angles are 15° - side and end relief and side and back rake – so I call it a Square Tool. It will have a 1/32” nose radius that will produce a very good finish on most materials.
> 
> The general process is the same for all turning tools since they will all have the same three flats. The specific angles may differ, depending on the desired geometry but you will grind them the same way.
> View attachment 140462
> ​Shown above is my belt sander. The tool rest is set at 15° and will not move for this tool. Should I need to change an angle, the rest will precisely set it in just a few seconds. I also use a ceramic glass platen liner to provide a long-lasting flat surface for the belt to run on; you cannot grind a flat if the platen itself is dished. Of all the mods you can do to a belt sander this platen liner is THE most important one. These liners are available from knife making suppliers, often under the name Pyroceram.
> 
> View attachment 140463​
> This is our blank, a high quality 3/8” HSS bit from Japan. Initially, I suggest you practice on mild steel key stock from the hardware store and switch to HSS when you are confident in your ability to grind what you intend.
> 
> *The Side*
> The first face to be ground is the side of the tool. I normally make the length of this face 1-1/2 to 2 times the size of the bit; in this case ~ ¾” long. For a general purpose tool I will angle the tool bit so that about 50-60% of the end of the tool is ground off when the side is done.
> 
> For illustrative purposes, I have drawn a line to show what I mean. It is useful for new guys to do this as it helps you to align your tool bit to the grinding media. As you get used to grinding you won’t need this line.
> 
> View attachment 140464
> ​To be very clear, as we grind the side we are grinding the *side cutting edge angle (*represented by the inked line*)* and the *side relief angle (*set by your table angle*)* at the same time. Don’t let the labels bother you; although you’re grinding a flat the result will be these angles.
> 
> View attachment 140465
> ​This is how it looks as I grind this side face. The push block is angled in the picture because I wasn’t paying attention when I took the picture but it is perpendicular to the platen in use. As I grind, my force is straight into the belt. You can see the ceramic glass platen liner in the picture above.
> 
> The inked line on the bit parallels the face of the belt. My left hand simply helps to move the tool back and forth across the entire surface of the belt. The block provides all the pressure straight into the belt to keep it cutting continuously and also aids in moving the bit side to side. As you grind, the tool will heat up; just dip it in cold water and move on. Now we just grind to the line, pushing into the belt and using its entire width to grind a flat even surface.
> 
> Below is the finished side face. To recap, we have created the side cutting edge angle by grinding along that line we drew on the top of the tool. We have also ground the side relief angle of 15° at the same time because that is what our tool rest was set to. If you want more or less relief angle on the tool then just change the tool rest angle … got it?
> 
> View attachment 140466
> ​*The End*
> Now we will grind the end face of the tool. The angle it forms relative to the side edge is called the *end cutting edge angle* and the clearance angle under this end edge is called the *end relief angle*, which is set by the angle of the tool rest.
> 
> For most tools I recommend that the end relief angle be kept the same as the side relief angle; in this case, 15°. Just this alone will reduce cutting forces and cutting temperatures versus standard geometry and you give up very little in terms of strength.
> 
> Since this tool is a general purpose tool, meaning it can turn, face or finish, it must be able to cut into a shoulder and then be able to face out. To accomplish this we will make the end cutting edge angle less than 90° so it can access corners without rubbing. I normally set it at 80°, which is represented here by an inked line:
> 
> View attachment 140467
> ​The table angle remains at 15° and I set up like this:
> 
> View attachment 140468
> ​For the end, the push block is moved up near the tip to provide both lateral support and some force to move the bit back and forth across the belt. My other hand holds that black line parallel to the face of the belt and provides the cutting force into the belt and also moves the bit side to side. The end face cuts fast – just grind it to the line.
> 
> View attachment 140469
> ​We have now ground the majority of the tool angles. If this were a tool for brass/bronze all we would need is to hone it, put a nose radius on it and the tool would be ready for use. For our tool, however, we have the very important rake angles to grind next.
> ​*The Top*
> The top of the tool houses the two most influential angles on a turning tool – the side rake and back rake angles. While they might seem hard to grind they are actually the easiest, as you will see.
> 
> View attachment 140471
> ​I normally make the depth of the top grind about 1 to 1-1/2 the dimension of the bit. Here, I have marked the side of the blank at ½” from the tip. I will line this up with the right edge of the belt to serve as a reference, as seen below.
> 
> My steel table will not provide adequate support for the tool on the right side of the belt so I have an auxiliary table that drops on top of my standard table that does have a support area. This auxiliary table has some angled lines scribed on its top that allows me to choose from a variety of angles. In this case, I am using the 15° line and the bit is brought to the belt without changing this angle. You can also ink a line on the tool rest, up near the belt to help you align if you need to. Once the bit is angled the inked line on the side of the tool bit is brought to the edge of the belt and the support block is brought into contact with the tool bit. I am now ready to grind the top rake angles but before I do that …
> 
> Note that the table angle sets the *side rake* angle; in this case, 15°. The angle I am holding the bit at as I feed it into the belt sets the *back rake*, also 15°. As I feed the tool into the belt I am cutting both rake angles at the same time.
> 
> Also note that if you use a belt sander you need to track the belt off the right side of the platen about 1/16” to avoid cutting the belt. This also creates a nice radius into the back rake.
> 
> View attachment 140472
> 
> ​To grind the rake angles all you do is use the push block to push the bit straight into the belt (or your wheel) – that’s all, a straight push. You do not move side to side here.
> 
> I visually align the front edge of the push block with the flat face of the platen and just push straight into the belt while my other hand maintains the 15° tool angle. The block really helps to direct your force – I would use one if I were you.
> 
> To orient you, the top of the tool is facing the belt. The side cutting edge is facing up, the back of the tool is touching the table and the bottom of the tool contacts the push block. Due to the angle of the table the belt will start to cut at the right rear of the top surface of the bit and as you grind, the ground surface will approach the side cutting edge and cut into it; then it will approach the very tip of the tool. Your goal is to stop the grind at the exact moment it reaches the tip. How do you know when the grind is getting to the tip? Just pull the tool away from the belt and look, and you’ll see something like this:
> 
> View attachment 140473​
> You can see that I’ve got a ways to go yet. To resume grinding, re-establish your tool angle and push. The flat that is currently ground into the tool will register itself on the platen if your right hand is relaxed. Now just keep grinding and checking until the grind reaches the tip of the tool, then stop.
> 
> You’ll see this:
> 
> View attachment 140474​
> If you have done this right the grind will extend all the way to the tip and there will be a nice curve ground into the rear of the top face of the tool. The tip of the tool will also be at the same height as the shank of the tool.
> 
> View attachment 140475
> ​We are done … almost. I normally use an 80 grit belt to redo each of the faces on the tool to remove the coarse shaping marks. This makes honing much easier to do. For this tool, I did not have a fresh 80 grit belt and had to hone a lot more than I normally would. Anyway, hone each face of the tool and put a nose radius on it.
> 
> I usually form the nose radius with my diamond stones as it is easier for me to control the size and shape that way. I hone a tiny flat with my stone at the very tip, being careful to follow the angle of the tip of the tool so that the flat is even, top to bottom. Then I gently round the edges of the flat so it blends into the side and end faces. I normally use coarse, fine and then extra fine stones to hone with.
> 
> Your goal as you hone is to remove all grind marks. If you use the same stones I use you will achieve a near mirror finish on your tool and the tool will be razor sharp so be careful with it.
> 
> You should have this when you’re done:
> 
> View attachment 140476
> View attachment 140478
> View attachment 140479
> View attachment 140477
> ​You now know how each of the tool angles in the typical textbook illustration is ground. Sorry if I took the mystery out of it for you.
> 
> View attachment 140481
> ​You also know how to change each of those angles to suit your needs – change the tool rest angle and the angle of your bit as you grind it. You can find these standard angles in any tool angle table on the net or Machinery’s Handbook. It is just as easy to grind a modified tool as it is to grind a standard tool and I hope this gives you the confidence to experiment.
> 
> Lots of guys think you need a jig of some kind to grind a good tool. As you can see, this is not true. In fact, jigs restrict your ability to alter your geometry and I personally think this is a deal breaker. The only instance I can think of where a jig is useful is for grinding threading tools.
> 
> Total actual grinding time for this tool was about 4 minutes. Honing takes a few more minutes. If you hone it after each use it will likely last you a decade or more and not require a re-grind so making one like it is a skill well worth learning. I hope this helps you to do just that.
> 
> Give tool grinding a go and remember … you’re just grinding three flats.
> 
> 
> Mikey
> 
> Addendum: Here are some links that will provide more information on tool grinding:
> 
> http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander/
> http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-2/#more-5888
> http://www.machinistblog.com/grinding-lathe-tools-on-a-belt-sander-part-3/#more-5897
> This was a fun discussion we had on the HM Forum:
> 
> http://hobby-machinist.com/threads/turning-tool-and-facing-tool-questions.36687/
> 
> ​


I can see that you have devoted a lot of time to your article and it is quite informative and succinct; however I take issue with the side and front clearences, they are quite excessive, to the point that they would materially weaken the cutting edge, besides making it easier for the too to "hog in"  I find that clearences of 8 to 10 degrees work fine, unless one is using Armstrong type tool holders, which require much more front clearance due to the 15 degree angle at which the tool is held in the holder. 
 I know that the following is off subject, which is turning tools, but I point it out anyway since many hobbyists have shapers; for those tools, the front and side clearences can and should be much less, in the order if perhaps 5 degrees; this is due to the fact that a turning tool advances in the cut on a spiral path, not the straight cut that a shaper uses; this also applies to internal shaping and slotter tools, which need very little clearance on the sides and front since they only advance in the cut while the tool is returning on its backstroke (if there is a clapper box, as with a slotter) and once the tool has cleared the cut  and starting another cut, as when used in a shaper or slotter that does not have a clapper box.


----------



## Sparkysparty

mikey said:


> I drafted the above sometime in September of last year but due to chronic laziness and honest busyness, I only just now put the final touches on it. There have been numerous discussions about tool grinding, carbide vs HSS and so on recently and that got me off my butt. It is my sincere hope that this helps someone get over the hump and learn to grind tools. Most of us don't own big, rigid, fast or powerful lathes. We own hobby lathes, typically in the 10-11" class with max speeds of 2500 rpm or so. For those lathes and smaller, HSS is usually the best tooling option and we can further modify those tools to enhance the performance of your lathes even more.
> 
> I hope this gives you a start.
> 
> Mikey



Hi Mikey, a big safety issue is wearing gloves on the grinder. If your hand gets caught skin will tear where as a glove will pull you in and not let go. I imagine you are doing this because the tool gets hot, keep a container of water near to keep dipping it into and this will also stop it getting discoloured causing annealing (softening) of the tool.
If anyone can find the plans for it, there is a vertical HSS tool holder that off-sets the tool vertically at an angle and you only need to grind the end or top as such, I used have the drawing but lost in computer files somewhere. Maybe I need to draw one up on CAD.

I see that it has been mentioned about HSS vs Carbide, the main issue is the power and speed of the machine. A very basic formula for cutting mild steel with HSS is RPM=9000/diameter turning, so if cutting 10mm bar it is 9000/10 = 900RPM, Carbide on the other hand is approx. triple that, so 2700RPM. if you are going the correct speeds you will get optimum tool life and better finishes. Also if you grind a small nose radius (approx. 0.5mm) on the end of the tool will help heaps with finish. 
Just to give you a bit of feedback on why I know all this, I am a toolmaker by trade (25 yrs) where we used HSS on a regular basis and I have been teaching Fitting and machining apprentices in a trade training centre (SkillsTech TAFE, Brisbane Australia) for the last 11 years, happy to pass on any other information.


----------



## mikey

benmychree said:


> I can see that you have devoted a lot of time to your article and it is quite informative and succinct; however I take issue with the side and front clearences, they are quite excessive, to the point that they would materially weaken the cutting edge, besides making it easier for the too to "hog in"  I find that clearences of 8 to 10 degrees work fine, unless one is using Armstrong type tool holders, which require much more front clearance due to the 15 degree angle at which the tool is held in the holder.
> I know that the following is off subject, which is turning tools, but I point it out anyway since many hobbyists have shapers; for those tools, the front and side clearences can and should be much less, in the order if perhaps 5 degrees; this is due to the fact that a turning tool advances in the cut on a spiral path, not the straight cut that a shaper uses; this also applies to internal shaping and slotter tools, which need very little clearance on the sides and front since they only advance in the cut while the tool is returning on its backstroke (if there is a clapper box, as with a slotter) and once the tool has cleared the cut  and starting another cut, as when used in a shaper or slotter that does not have a clapper box.



The tool I showed is my own design and it has worked well for me for about 15 - 20 years now. I used it as an example because I like it and wanted to share it but the real goal of the post was to show the guys how to grind a tool while clarifying what they were grinding as they do each face. This geometry stuff is confusing until you get your head around it. While I think the tool itself is extremely useful in and of itself, the same approach to grinding a standard tool with the angles you prefer can be used. 

As to materially weakening the edge with greater side and end relief angles, maybe that might be an issue in a large lathe in a production environment. In a hobby shop, I don't see it as an issue. The standard tool angles are okay and have been around forever but there is no reason why we cannot change them if they improve the function of the tool or allow a smaller lathe to work like a bigger one. In a hobby shop, where we do one-off stuff most of the time, edge retention is not an issue. I have tools that are over 10 years old and are still razor sharp.

I am an advocate for modifying tool geometry and yes, I use larger relief and rake angles. I do this to reduce cutting forces and cutting temperatures that tools with standard geometry produce. If you take a little Sherline or Taig, or a 6" Atlas lathe that many, many hobby guys own and take a 0.025" deep cut with a roughing tool with those angles you cited, it will begin to chatter. The tool shown in this thread will easily take double that depth of cut, produce a nice finish and then cut curlicues in paper afterwards. Larger lathes can handle more standard geometries but smaller lathes greatly benefit from geometry changes. They are not powerful or rigid enough to break a tool or an edge. I also own an Emco 11" lathe and alter the geometry used on every tool on that lathe. These tools cut more efficiently for me and I have had absolutely no issues with edge breakdown. Nor have I ever had a lathe tool dig in. Well, except once or twice in brass. 

No disagreement here, benmychree. If a user wants to use standard tool angles then no problem. I just wanted to make sure they can grind it.


----------



## mikey

Sparkysparty said:


> Hi Mikey, a big safety issue is wearing gloves on the grinder. If your hand gets caught skin will tear where as a glove will pull you in and not let go. I imagine you are doing this because the tool gets hot, keep a container of water near to keep dipping it into and this will also stop it getting discoloured causing annealing (softening) of the tool.
> If anyone can find the plans for it, there is a vertical HSS tool holder that off-sets the tool vertically at an angle and you only need to grind the end or top as such, I used have the drawing but lost in computer files somewhere. Maybe I need to draw one up on CAD.
> 
> I see that it has been mentioned about HSS vs Carbide, the main issue is the power and speed of the machine. A very basic formula for cutting mild steel with HSS is RPM=9000/diameter turning, so if cutting 10mm bar it is 9000/10 = 900RPM, Carbide on the other hand is approx. triple that, so 2700RPM. if you are going the correct speeds you will get optimum tool life and better finishes. Also if you grind a small nose radius (approx. 0.5mm) on the end of the tool will help heaps with finish.
> Just to give you a bit of feedback on why I know all this, I am a toolmaker by trade (25 yrs) where we used HSS on a regular basis and I have been teaching Fitting and machining apprentices in a trade training centre (SkillsTech TAFE, Brisbane Australia) for the last 11 years, happy to pass on any other information.



Thank you, Sparkysparty. Like Ozwelder pointed out, gloves around a rotating machine is a danger to be aware of. And I am aware of it. I don't use gloves to protect from the heat; I use it to avoid losing meat when my hand meets the belt or when the belt snaps on me. If you look at the pics in the original post, the hand near the belt is not gloved but the one that applies the force is. One slip and that hand meets the belt - I know, I've done it. I am inordinately careful and mindful of safety in my shop and I do not use gloves at any other time but a sanding belt will cut to the bone if you touch the edge and it will cut deep if the belt snaps on you and the tag end hits you. I have scars to prove both so I choose to wear a glove. 

Please understand that I appreciate the advice and am not disregarding it in the least. The guys have been warned earlier about gloves and thanks to you, are warned again. If someone gets his hand ground up in a bench grinder while wearing gloves then, well, he was warned. 

Hey, with all your experience and credentials, you will be a valuable resource here on HM. Welcome to the community!


----------



## stragenmitsuko

A while back I needed to make a poly v-belt pulley . 
A tool was needed , much like a threading tool , but with an included angle of 40°
instead of 60° . 

So I made one , I'm the proud owner of a clarkson MKIII  t&c grinder wich makes setting the angles easy , 
ground it , honed it ... as usual . 

As it's a form tool , no rake was ground . 

That tool just wouldn't cut . 
Tried it dry and with lube , above , on and below centre . 
Tried feeding in at an angle like threading 
Tried pre cutting the grooves with a parting tool 
No avail . The last pass when cutting to depth would make the tool bind , chips would rub 
and become sticky , finish was awfull and would have eaten the belt in no time . 

So finally , I gave the cutter  a few ° of back rake . 

Look an behold , a whole new tool , able to straight plunge cut the grooves without a hickup , and with a shiny finish . 

Toolgrinding , it's a lost art wich I'm very hard trying to master .  

Pat 

Mikey , could you maybe post some pictures of toolbits for boring bars and fly cutters ?


----------



## mikey

stragenmitsuko said:


> Mikey , could you maybe post some pictures of toolbits for boring bars and fly cutters ?



Pat, I've pretty much gone over to carbide (gasp!) for boring on the lathe and flycutting on the mill. Yup, me, the HSS advocate for smaller machines, uses carbide for these jobs. Back when I began in this hobby I only used HSS tooling for boring and flycutting but I learned that the pointy end of things isn't all there is to it. 

Boring on the lathe is about consistency and predictability and it is very difficult to beat a solid carbide inserted tip bar in a deep hole with tight tolerances. Imagine boring a 4" deep hole just under 1/2" ID, then cutting a thread relief groove at the bottom and cutting a thread an inch from the bottom. I can't do it with a HSS bar but I can do it easily with a Circle Machine QCMI solid carbide bar and get a Class 3 thread fit and a consistent bore diameter all the way down. Those steel bars that take HSS bits are limited by their modulus of elasticity and cannot go as deep for a given bar diameter so I gave up on them. Solid HSS or cobalt bars or brazed carbide bars all have similar limitations for deeper bores, although they're fine for shallow bores into which they fit.

I do use Borite cobalt bars in my boring head on the mill because my speeds are more limited there and a sharp cobalt bar cuts very well at lower speeds. I tried an inserted tip bar but found that the cobalt bars were more accurate for me. This has everything to do with having only bench top mills that can't go fast without the mill walking across the floor.

Similarly, a flycutter works best at high speeds. I used to have a dozen LH HSS cutters ground and sharpened and I would go through 2 or 3 of them squaring a block of steel that needed to be truly square. I gave up when I discovered that a single insert could do it better, with as good a finish as I could get with HSS, provided I could get the speed up. And that insert was still going a year later. It became difficult to continue using HSS after that. 

The bottom line is that I don't use HSS for these processes anymore ... sorry. 

Mike


(If you wish to know more about my boring bar choices, PM me and we can discuss it. I have some very good reasons for it.)


----------



## Tozguy

Hukshawn said:


> ill try the higher speeds. Just get it over with and learn.
> 
> What's the proper way to grind those harder tools? Specific wheels? Belts? Diamond?



Hukshawn, have you ever tried these ceramic belts for wood? They are supposed to be more durable for metal 'sanding' but the regular price is scary. I bought a couple of them during a sale and will try them on metal at the next opportunity. I do so little belt grinding/sanding of either wood or metal that my comparison won't mean much but it will satisfy my curiosity, I hope.


----------



## churchjw

Thanks for the post.  Great write up.


----------



## Hukshawn

Tozguy said:


> Hukshawn, have you ever tried these ceramic belts for wood? They are supposed to be more durable for metal 'sanding' but the regular price is scary. I bought a couple of them during a sale and will try them on metal at the next opportunity. I do so little belt grinding/sanding of either wood or metal that my comparison won't mean much but it will satisfy my curiosity, I hope.



Hey, no I generally use the aluminum oxide open grain cloth back belts for the drum and stroke sanders. the durability has a lot to do with how often you dress the belt. I dress my belts about every 5 minutes of sanding time. the longer you run a loaded belt, the faster you burn it out. with that process I generally get 10 hours of actual contact time before I change a belt. Which for me, is usually several weeks. which is pretty good for an economy belt. my big 168" belts are usually only $20-$30 each, the better belts for a machine that big would cost 3-4 times that. 
But I'm going to look into appropriate metal cutting belts and discs for this little delta sander I'm using to grind. I've got a good handle on the tool grinding now, this machine and this process is a viable option for me so I'm going to try to improve on the machine make it work.


----------



## mikey

Okay, this thread is still being actively viewed. When I started this thread, I hoped it would be a place for new guys (and not so new guys) to show their tools and maybe have the more experienced tool grinders suggest ways to improve them. If embarrassment is holding you back from posting, please understand that we have all been there and nobody with even a smidgeon of memory will make you feel bad. Sometimes it just takes a word or two for something to click in your brain and have it all fall into place and I know there are some really knowledgeable guys on this forum who can give advice that can do exactly that. 

Also, if you have tools to share that you are proud of or simply wish to show to others like Dan S did, bring it! His post helped a friend of mine to make a purchase decision. 

So, open invitation, guys ...


----------



## schemer

mikey said:


> Thank you!
> 
> I am using an old Craftsman 1/2HP 2 X 42" belt sander. I can't even remember when I bought this machine. Its over 15 years for sure, maybe more, and it is absolutely reliable. They are still available as a somewhat anemic 1/3HP version nowadays. I have one of these weaker sanders and I can completely stop the belt when grinding a tool so I cannot recommend it for tool grinding. They are sold by Palmgren, Dayton and others.
> 
> You would think that anything from Sears is basically junk but this is one of the more intelligently designed sanders for tool grinding. The reasons I say this is because the platen is easily replaced with a  piece of angle iron to which a piece of ground steel can be attached. To this, a glass liner can be adhered and the whole thing shifted back to allow the glass liner to run even with the front of the two wheels. The right side of the platen is entirely exposed; there is no sheet metal in the way, and this allows full access to the belt for grinding the rake angles on a tool. This access thing makes most belt sanders on the market (except for the 2 X 72's) unacceptable to me.
> 
> This sander also has a chassis that is flat so a template with holes to angle the tool rest is easy to attach. The tool rest is simple to fabricate and allows for angle changes in seconds without tools. If you're interested in more on this sander, see here: http://www.machinistblog.com/modifying-a-craftsman-2-x-42-inch-belt-sander-for-tool-grinding/
> 
> The belt tracking mechanism is simple and precise. It does not allow the belt to drift unless the tension spring gets weak and this is only an issue if you're grinding huge back rake angles. If you can't tell, I love this tool!
> 
> I've been looking for a replacement or substitute grinder for years and haven't found one that satisfies my needs. The two things I mentioned - ability to attach a platen and have the right side completely accessible and the ability to attach a tool rest template - are important to me. If anyone spots something like this, let us all know.



Mikey,
  Thanks for the info on the grinder. As always, good stuff is harder to find when you are looking for it unless you want to pay the piper. Thanks for the link with all the added build/mod info.


----------



## mikey

schemer said:


> Mikey,
> Thanks for the info on the grinder. As always, good stuff is harder to find when you are looking for it unless you want to pay the piper. Thanks for the link with all the added build/mod info.



Ain't it the truth? I'll keep looking and post it here if I find a good substitute grinder.


----------



## ch2co

Following Mikey's request. Here's my attempt and question.
I’m a complete novice who picked up a used 10-22 lathe, a mini mill, and a ton and a half of accessory parts from an even older fellow than I am. You mention a *trepanning* tool, which was what I needed for my first real lathe job. I was making a series of different sized rings from 5/8” thick aluminum plate. These are used for: a. holding a telescope (tube) so that it can be very firmly attached to its mount, and, b. for mounting other accessory items to telescope tubes. My first go at it was basically to hold the plate in a 4 jaw chuck and machine away the entire center of the plate by making a series of passes until all of the plate was machined away except for the outer frame that the chuck held. Then the part was held by the newly formed inside “hole” and the outside of the remaining (square) plate was machined away forming a round ring.

This was a great learning experience in lathe work all done by trial and error by using various cutting tools that  had come with the lathe. The biggest problem was that it took forever to hollow out a 6-1/2” thru hole and then I ended up with a HUGE pile of swarf. Then I asked how to do it on this site and someone (thank you) mentioned “trepanning”. After looking that term up online I discovered that I already had a HS steel trepanning tool in one of the many boxes of stuff that came with the lathe.

However,as soon a I started cutting a groove in one of the pieces of aluminum I found that the bottom edge of the 1/2” high trepanning tool was scraping against the outside edge of the newly cut groove producing a lot of extra heat and a horrible squeal, no mater how much lubricant I poured on the part. Unacceptable! I could only cut a groove into the plate about twice as deep as it was wide, aprox. 1/8” wide by 1/4” deep. I tried to grind a new tool from an1/8 x 1/8 tool steel blank. It worked! it cut a groove into the plate 1/8” wide by about an 1/8” deep and then the tip promptly broke off. Hmmm. Something to do with stress greater than strength I guess. I then went back to the original tool and took it over to my little bench grinder and (without gloves) ground away the lower outside edge of the tool very roughly (crudely) rounding it out so that it cleared the outside radius of the groove. This worked fairly well, but still the tool wouldn’t cut all the way through the plate. Was it cutting speed, type of cutting fluid, poor cutting geometry, too small of a lathe, or what?  I finally started to just cut the groove wider by cutting a second groove on the inside right next to the previously existing groove. Then I could go back and cut the original groove deeper repeating this process until finally cutting through the entire plate. Much quicker and much quieter, and much much less swarf, AND I ended up with a nice remnant in the form of a disk that could be used later for something else instead of the big pile of swarf. So far I have turned out 18 such rings some of which came out of the previously formed remnant disks.
So now I ask, how do I make deeper trepanning cuts using only a single pass? I’m happy with what I’ve done so far but there must be ways to be able to due it quicker and more easily.  Here’s a photo of my current tool and a few shots of my techniques and final products so far. I don’t have a belt sander. (yet)

 By the way, when I first googled trepanning I came up with the way that early man got rid of headaches or evil spirits or something, by trepanning a round hole through the skull. Ahhh, relief! Today I just grab a couple bottles of beer and down the contents. Preferably a good tart hoppy IPA.


----------



## mikey

Great post, ch2co, especially that part about grinding without gloves - made me laugh.

A trepanning tool has several features: it has back rake, which is the equivalent to side rake on a turning tool. It has side clearance on either side of about 5 degrees. It has front clearance of between 10-12 degrees and this clearance starts at the tip and goes to the heel of the tool; this enables the tool to progress smoothly into the cut without the lower edge of the tool rubbing. This is very similar to a shaper tool.

On your tool, it looks like you have back rake in the form of a curved radius that should work. It looks like you have side clearance, although I cannot tell how much and cannot see the other side but they should match. You have front clearance but not enough and it does not extend all the way to the tip. It looks like the area just under the cutting edge is flat and this will rub. The clearance needs to come up all the way to the cutting edge.

So, I would try several things with this tool. I would grind some more clearance under the cutting edge and bring it to the tip of the tool. I would also bring the side clearance grind all the way to the top of the tool and then hone the tool to get sharp edges.

I suggest a lot of WD-40 as a lube. You are basically parting here and you need lube. I suggest starting with a fairly low cutting speed - maybe 300 rpm or so - and increase as much as the tool allows.

If you try this, please let us know how it goes. You make nice rings, really nice!


----------



## Dan_S

ch2co

take a look at this tool i just made real quick in fusion 360. just click the link and it will give you a 3d view  that you can manipulate in your browser.

https://myhub.autodesk360.com/ue294d617/g/shares/SHabee1QT1a327cf2b7a8c1a3f3a4e65e965?guid={"type":"Design","asset":"c46ea498-83ed-4de2-a909-58168fa7b580"}

Things to note:

outer edge has a radius to clear the outside diameter of the grove being cut.
inner edge has a strait grind to clear the inside diameter.
look down from the top and you will see the tool narrows as you go from the cutting edge to the shank. The taper is exaggerated, you only need 1 or 2 degrees. If you don't have some taper, it will rub as you plunge in. The tool will heat up, expand, and then seize in the work and break off.  
For something like this you want to go as slow as you can, and you want to have the compound and cross slide locked.


----------



## Old Squier

Wow! Terrific article. Thanks for posting it. 

Sent from my SM-G530T using Tapatalk


----------



## mikey

Old Squier said:


> Wow! Terrific article. Thanks for posting it.
> 
> Sent from my SM-G530T using Tapatalk


 
Thank you!


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## ch2co

Thanks Mike and Dan
First: Mike, I can't open your picture, no matter what I do, I just get the little box with a red X through it. 
I now use WD40 on aluminum, again by trial and error using every lubricant in my shop. 
The tool has to be able to cut all the way through the 5/8" plate.  This means the the narrow blade needs to be quite long. On the last and largest 
set of rings, I cut it from one side to just past 1/2 way through then I flipped the piece and cut from the other side till they met.  It only took a little cleanup to get the ID clean and smooth. I have found out by trial and error, the necessity to keep everything locked down that doesn't need to be moving. I also built a new compound clamp  
with 6 lockdown bolts to avoid the front to back rocking of the compound which is a known problem on the 10-22 lathe. Thanks again to those on the 
forum for the suggestion and dimensional prints. 
I think that I really would benefit from a belt sander rather than my old bench grinder for making and cleaning up my tools. I have also found that
a diamond dust sharpening stone works great for the minor tool touchups between cuts. 
Dan: Thanks for the Fusion 360  3D print. I really need to learn how to use that program. So far I'm a strictly 2D print man. But that takes time that I could
use for other things, like lathe and mill work. 
The front to back taper of the tool makes a lot of sense. My current tool is wider at the cutting edge, then it narrows down, but the sides are still parallel.
The cutting speed is always something that I can easily adjust (a VFD) and I still just use trial and error when adjusting it. When you say 300 rpm, that equates
to a lot of difference in surface feet per minute depending on the diameter I'm cutting at the time. Could you suggest a SFM for trepanning?
Thanks to all.

Chuck the grumpy old guy aka ch2co


----------



## mikey

Chuck, the pic was just the shot of your tool, that's all. 

There used to be a guy who sold HSS parting tools, ground from a 3/8" square bit. It had a blade almost 5/8" long but I can't find him on ebay now. My last trepanning tool was made from one of his tools and I just reshaped it for my use. If I were to do it again, I would grind it like your current tool but get the clearance angles right. 

As for cutting speed, you'll have to try it. With the aluminum piece I did last I started at 300 rpm and increased speed until the blade cut with just slight resistance to feed. I don't know what the speed was; I don't have a tach installed and didn't bother to check with my manual tach. Sorry if this isn't much help but like all cuts, you have to adjust to the cut.


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## Dan_S

ch2co said:


> Could you suggest a SFM for trepanning?



In aluminum, nothing over 600 sfm. at large diameters, you are usually limited by machine rigidity and HP. another thing to note, is just like parting you need to feed fast enough to get a continuous cut, if you don't the tool flex and generate chatter.


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## ch2co

Chatter = Squeal?


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## Dan_S

ch2co said:


> Chatter = Squeal?


Without hearing it, it could be either or, or both.


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## ch2co

The reason that I ask, is that my biggest problem when cutting with this tool is a continuous very high pitched squealing that drives me nuts even with my head phones (ear plugs) on.  I would think that chatter is an intermittent but variable 
speed interrupted event. ??


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## mikey

That continuous sound is probably rubbing, Chuck. I'm betting on the area right below the cutting edge doing the rubbing.


----------



## markrf555

Great thread on how to grind HSS.  I did this on my 1/4" HSS cutters for my lil sherline few months back. Used bench grinder at lower speed and generated a lot of heat but got basic shape needed and honed it on my wet stones (have few of those cuz mainly a woodworker and hone chisel and plane blades) I got a quick lesson on cutter angles and rake etc... the square tipped HSS cutter (trying to cut up to shoulders) and the little sherline quickly let me kno that much contact on the aluminum wasn't gunna work. I basically made a 1/4" wide parting tool/cutter wit bout 15deg rake on front face and tried to cut like do on my wood lathe. NOPE!

Really like the sander idea as I made a 2x72" belt sander for knife making but use it for lots things in my shop. Will try to post pic of it and my cutters. 

I'm new to this forum and machining in general so need to learn cutter shape needs before I cut many more. Thanks


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## markrf555

Pic of my belt sander


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## solman

Hi all ,New member here and also new to the lathe hobby. I have a HF 7x10 I got from a friend at a great deal. I followed this thread and tried my hand at grinding some keystock to the tune of the first post. Came out fine on my second try. Did a few more for practice and now ready to try on some HSS I ordered.
Thanks to Mikey for making this easy to follow and a great tutorial. 
The cutters I have are the inserts and the HF carbide on the red arms.  I don't seem to get a nice finish cut on cold rolled steel. Its ok on aluminum which is easier to cut.
 I did have a question though. 
Why remove so much material on the first cut of the side? Is this for all around cutting or for specific materials?
Thanks again,
Solman


----------



## solman

Mark,  Thats a sweet sander you made . I have a Kalamazoo 1x42 which runs at half speed and I like it, but yours looks much better for knife making.


----------



## mikey

markrf555 said:


> Great thread on how to grind HSS.  I did this on my 1/4" HSS cutters for my lil sherline few months back. Used bench grinder at lower speed and generated a lot of heat but got basic shape needed and honed it on my wet stones (have few of those cuz mainly a woodworker and hone chisel and plane blades) I got a quick lesson on cutter angles and rake etc... the square tipped HSS cutter (trying to cut up to shoulders) and the little sherline quickly let me kno that much contact on the aluminum wasn't gunna work. I basically made a 1/4" wide parting tool/cutter wit bout 15deg rake on front face and tried to cut like do on my wood lathe. NOPE!
> 
> Really like the sander idea as I made a 2x72" belt sander for knife making but use it for lots things in my shop. Will try to post pic of it and my cutters.
> 
> I'm new to this forum and machining in general so need to learn cutter shape needs before I cut many more. Thanks



Thanks, Mark, and welcome to the HM community! That grinder is going to make things a lot easier for you to grind good tools - it came out really nice!

The Sherline lathe is an excellent lathe. I love mine and use it a lot, despite having a much larger one in my shop. Like all small lathes, it is limited in its power, rigidity and speed, and the key to unlocking every bit of the potential in that lathe is your tooling. With the wrong tool or tool shape, the lathe will balk and fight you but with the right tool it will perform with great precision and will take cuts that will surprise you.

Spend some time grinding some tools from mild steel keystock until you are comfortable with grinding. Those practice tools won't hold an edge long but they will cut. When you feel that you have a handle on the material in the OP, try one in HSS. I think you'll be pleasantly surprised at what your little lathe can do. Show us your results if you've a mind to - I would be interested in seeing them.

Again, welcome to HM. This is a wonderful community and you'll learn a lot from the posts here. You'll learn even more by asking questions; there is no other forum that is as open and helpful to beginners than this one.


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## Wreck™Wreck

mikey said:


> I drafted the above sometime in September of last year but due to chronic laziness and honest busyness, I only just now put the final touches on it. There have been numerous discussions about tool grinding, carbide vs HSS and so on recently and that got me off my butt. It is my sincere hope that this helps someone get over the hump and learn to grind tools. Most of us don't own big, rigid, fast or powerful lathes. We own hobby lathes, typically in the 10-11" class with max speeds of 2500 rpm or so. For those lathes and smaller, HSS is usually the best tooling option and we can further modify those tools to enhance the performance of your lathes even more.
> 
> I hope this gives you a start.
> 
> Mikey


Excellent job, you have way to much free time however, this is a good thing I suspect.


----------



## mikey

solman said:


> Hi all ,New member here and also new to the lathe hobby. I have a HF 7x10 I got from a friend at a great deal. I followed this thread and tried my hand at grinding some keystock to the tune of the first post. Came out fine on my second try. Did a few more for practice and now ready to try on some HSS I ordered.
> Thanks to Mikey for making this easy to follow and a great tutorial.
> The cutters I have are the inserts and the HF carbide on the red arms.  I don't seem to get a nice finish cut on cold rolled steel. Its ok on aluminum which is easier to cut.
> I did have a question though.
> Why remove so much material on the first cut of the side? Is this for all around cutting or for specific materials?
> Thanks again,
> Solman



Hi Solman, and welcome to the HM community to you, too. I'm really glad to see that you tried grinding tools from keystock. In my opinion, that is the fastest way to learn tool grinding. It does take some time to learn how to move your hands and to clarify the various tool angles in your head; keystock is the best way to do that.

The answer to your question is more complicated than it seems. You actually don't have to remove so much material from the cutting side of the tool. The Brits often use a knife tool as the default turning tool and that tool has a straight cutting side - NO angle. The side we're discussing is called the side cutting edge and the angle it is ground at is called the side cutting edge angle. A knife tool has a side cutting edge angle of zero.

In times past, turning tools were oriented with the shank of the tool perpendicular to the work. In this position, the side cutting edge angle gave the user the proper LEAD ANGLE for that particular tool. To be clear, the side cutting edge angle = the lead angle when the tool was perpendicular to the work. Roughing, facing and finishing tools all had their own side cutting edge angles and when oriented perpendicular to the work the lead angle that resulted was appropriate for the function of the tool. For example, a roughing tool has a shallower lead angle vs that of a finishing tool. This shallower lead angle allowed a roughing tool to take deeper cuts without chattering. The larger lead angle of the finisher allowed for a much finer finish but it would chatter more with deeper cuts. The reason lead angle influences the potential for chatter is that cutting forces increase as more of the side cutting edge comes into contact with the work; the more contact, the more potential for chatter but with shallower depths of cut we get better finishes. If the above is true then angling a roughing tool so that its lead angle is the same as a finisher should improve the finish, right? If you do this, you will find that a roughing tool will finish just fine.

So, tool shapes in the past reflected the way the tools were used. That is why there were roughers, facers and finishers. Nowadays, with the much greater mobility of our quick change tool posts, we can use any shape that gives us the strength we need and we simply adjust the angle of the tool to suit our purpose. The tool in the OP is one such shape. It has enough mass in the tip to rough, it has enough clearance to face into a shoulder and then face out and it can finish very well with the right lead angle. We simply angle to tool to allow it to perform each of these functions.

Now, if you take a turning tool - a knife tool or a general purpose tool - and you perform roughing, finishing or facing functions by changing the tool post angle to suit, you will find that the lead angle that works best for the particular task is very nearly the same as the old time tools that were oriented perpendicular to the work. Interesting, eh?

So, the tool shape is not critical provided it is strong enough for the task and allows access to shoulders if that is important to you. Keep in mind that we are talking only about tool shape here. The actual geometry of the tool is another matter. Roughing, finishing and facing tools cut with different parts of the cutting edge and this is greatly influenced by the rake angles. The strength and efficiency required for these different functions is influenced by the relief angles. And the rake and relief angles are influenced by the material being cut.

In addition, the size of the lathe matters. Where a larger lathe can rough with shallower relief and rake angles, a smaller one requires greater rake and relief angles to produce an equivalent depth of cut. The reason for this is that different geometries produce different cutting forces so the tools used on a big lathe _should_ differ from those used on smaller lathes. This is the key advantage to HSS tooling - we can change the geometry to suit the purpose and the lathe.

The bottom line is that shape is not as important to understand. Find a shape that suits your needs and go with it. Spend some time understanding what the relief and rake angles do and learn to use them to your advantage. Until then, try the tool in the OP. It will keep you turning until you find your own design to meet your needs.

I hope I explained this to your satisfaction. If not, let me know and I'll try again.

Welcome to HM, Solman!


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## mikey

Wreck™Wreck said:


> Excellent job, you have way to much free time however, this is a good thing I suspect.



Thank you. Wreck! Yup, retirement is a very good thing!!!


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## solman

Mikey
Thank you for the clarification


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## markrf555

mikey said:


> Thanks, Mark, and welcome to the HM community! That grinder is going to make things a lot easier for you to grind good tools - it came out really nice!
> 
> The Sherline lathe is an excellent lathe. I love mine and use it a lot, despite having a much larger one in my shop. Like all small lathes, it is limited in its power, rigidity and speed, and the key to unlocking every bit of the potential in that lathe is your tooling. With the wrong tool or tool shape, the lathe will balk and fight you but with the right tool it will perform with great precision and will take cuts that will surprise you.
> 
> Spend some time grinding some tools from mild steel keystock until you are comfortable with grinding. Those practice tools won't hold an edge long but they will cut. When you feel that you have a handle on the material in the OP, try one in HSS. I think you'll be pleasantly surprised at what your little lathe can do. Show us your results if you've a mind to - I would be interested in seeing them.
> 
> Again, welcome to HM. This is a wonderful community and you'll learn a lot from the posts here. You'll learn even more by asking questions; there is no other forum that is as open and helpful to beginners than this one.



Yes love the Sherline, it was my first lathe and came with a nice set of HSS cutters and there is alot of information on them included. I have some experience (self taught) on grinding HSS wood turning tools so tackled the HSS lathe cutter but as I said need to learn the appropriate angles and shapes, but don't know until you do! I'll post some pics of my cutters this week when can get back in the shop and out of work. I will post my mistakes too.

Also thanks Solman, the belt sander was a great learning experience and project. Commercially avail ones (2x72") are $1000-2000 and didn't want to drop that, so built mine mostly from scratch. got the wheels (plastic not metal) and several other parts for it from an Ebay co that is great and priced right, then made rest of stuff and got an old 1hp elec motor from a motor shop here in New Orleans. I have a total of about $250 in it, anyone wants the plans or help, shoot me a message or email. I can also do a thread on it. very proud of it and works like a charm. think using Mikey's great tutorial and some jigs and plywood push stick (great idea btw), will be able to really dial in some cutters!


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## markrf555

solman said:


> Mark,  Thats a sweet sander you made . I have a Kalamazoo 1x42 which runs at half speed and I like it, but yours looks much better for knife making.



THanks. I also got a Kalamazoo 1x30 but needed a big dawg, so made that one. Will post a thread on it, cuz was pretty easy to make and saved a ton of cash doing it.


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## mikey

markrf555 said:


> think using some jigs and plywood push stick (great idea btw), will be able to really dial in some cutters!



Looking forward to your result, Mark. BTW, 3/8" square bits work better on the Sherline if you have them. Your belt sander will make short work of it for sure.


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## markrf555

mikey said:


> Looking forward to your result, Mark. BTW, 3/8" square bits work better on the Sherline if you have them. Your belt sander will make short work of it for sure.




Yes I ordered Sherline's 3/8" tool holder and will get some 3/8" HSS blanks for it. I quickly learned the importance of quick change when using that lathe for my first big machining project. everytime I had to change the cutter had to realign and center. took me 7 hrs to cut out the rigid alum risers for my harley, but they worked! Will prob machine a few 3/8" holders for it or a 4 way holder, pretty simple design


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## N2XD

Matt,
      Could you send me more information on your belt grinder? Thanks


John


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## Dan_S

One thing I would add, is buy a range of HSS too blank sizes. When I first started, I only used 1/2" square blanks and it was really frustrating, because it took forever to grind a new blank. Today I keep a  1/8", 3/16", 1/4", 3/8", & 1/2" square blanks on hand, and choose the appropriate size for the task at hand.


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## EmilioG

Great write up Mikey. I have them all saved as .pdf files and I always refer to them. Thank you.  You have helped me and many others learn.
That Craftsman belt sander is the Unicorn of belt sanders.  They don't come up often and your mods make the work better. Nice.
One question; Are chip breakers on lathe tools important? Will it make a big difference on heavier cuts?  I've seen Chip Breakers ground with Dremel tools.


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## mikey

EmilioG said:


> One question; Are chip breakers on lathe tools important? Will it make a big difference on heavier cuts?  I've seen Chip Breakers ground with Dremel tools.



Thank you for your kind words, Emilio. Like everyone else, just trying to help.

Chip breakers seem to be important to some folks, which is fine, but they are more trouble to grind than they're worth, in my opinion. I'm not just saying that because at one point I spent a lot of time grinding them and seeing for myself what the fuss was about. Let me be clear; chip breakers work if you grind them properly and use them under the right conditions. They are not a panacea for all cutting woes.

A chip breaker has to be near enough to the cutting edge without compromising that edge, and it has to be wide enough to guide the chip. I found that a V-shape doesn't work well because the chip often doesn't flow down the initial face; it goes right over it. What does work is to grind a V and then grind down the front half, toward the cutting edge, and then re-grind the edge. If you look at a chip breaker on a carbide insert you will find that there is a clear cutting edge and a bump to deflect the chip to encourage it to curl and break; this is the same thing I did on a HSS tool and it works much better than a V-shape. It also takes a heck of a lot of work to make one. You can dremel all you want but I bet it won't work much better than having no chip breaker at all. With that said, maybe I have no talent for this sort of thing so take it for what its worth. 

I found that the right speed and feed works nearly as well as my early attempts. Aluminum and stainless are the two materials that are notorious for making long, stringy chips but even carbon steels will do it if you take a shallow cut slow enough. If you take a deep enough cut at a fast enough feed rate, aluminum will chip off fine. Granted, some gummier alloys will string out regardless of what you do but for the most part, taking a heavy roughing cut at a slightly faster feed rate helps a lot. To be honest, I just live with the chips and make the cuts I have to make. Sometimes I have a big piece to cut and can take a big roughing cut but more often I'm starting with a piece that is near to my finished size. In that case, I get strings so I speed up my feed and hope for the best.

So, the bottom line FOR ME, is that I don't bother with chip breakers anymore. I have come to the conclusion that grinding a tool that is efficient and cuts well is more important than what it does to the chip, and that it is up to me to use that tool well. Hope this clarifies my personal position.


----------



## rwm

Mikey- early in the thread you mentioned a Pyroceram platten liner? I have never used one. How often do those come loose or break? What happens when they do? It it catastrophic or dangerous?
Robert


----------



## EmilioG

I've been researching Pyroceram liners also. I've read that some people use JB Weld and others use carpet double side tape.
Henkels, Dow Corning and others have high temp adhesives, so I'm looking at those.  There is a good metal powder adhesive that I'm waiting
on a sample for. If I could drill and countersink Pyroceram, I may use low profile screws with adhesive, I just don't know how well that material drills.  Mikeys' grinder platen seems well constructed., but I'll let Mike answer that.


----------



## mikey

rwm said:


> Mikey- early in the thread you mentioned a Pyroceram platten liner? I have never used one. How often do those come loose or break? What happens when they do? It it catastrophic or dangerous?
> Robert



My first one lasted about 11 years before the JB Weld broke loose. When it did, it came loose because a belt snapped so I guess there was some shock to the plate. I did not have a ledge under it like I should have and it did drop down so that's not a good thing but it didn't crack at all. My replacement one has two 8-32 socket head cap screws under the lower edge of the Pyroceram so even if the JB Weld comes loose, it shouldn't drop down. The danger, of course, is broken glass flying in your face so that's another reason to be wearing safety glasses.

I have heard of others using double-stick tape. In my opinion, this is dangerous. There is some heat build up when grinding tool steel and I would not trust tape. JB Weld has a high enough heat rating that I don't worry too much about it. Before applying your epoxy, it is necessary to clean the platen and the back of the Pyroceram really well after roughing both surfaces; I use lacquer thinner for this. 

If you use anything other than JB Weld, be sure the heat rating is at least as good, if not better than, JB Weld. I apply a thin layer of the stuff and then use spring clamps over the entire surface - so maybe 6 clamps holding it in place. Then I let it cure for at least 24 hours before use.


----------



## rwm

Where did you find your liner? I am having trouble finding it on eBay?
R


----------



## mikey

I get them from USA Knife Maker. Mine is 2 X 9" but they are out of stock right now.

http://usaknifemaker.com/catalogsearch/result/?cat=0&q=platen+liner


----------



## mikey

N2XD said:


> Matt,
> Could you send me more information on your belt grinder? Thanks
> 
> 
> John



John, I totally missed your request - my sincere apologies. I detailed my sander here: http://www.machinistblog.com/modify...inch-belt-sander-for-tool-grinding/#more-5349

Please let me know if you need more info.


----------



## ddickey

Made a few practice pieces out of key stock. I made the first real tool today. Took a very short cut on a piece of hot rolled from Menards. Man I think it looks good. I know a short turn but will try more later.
One thing I'm really having frustration with is 
	

		
			
		

		
	



	

		
			
		

		
	
 the back rake. It is very difficult with the table I have.
Thanks Mike for the awesome write up.


----------



## ddickey

Trying to grind 
	

		
			
		

		
	



	

		
			
		

		
	
  the back rake


----------



## Dan_S

Looks like you need to make a U shaped wrap around rest.


----------



## benmychree

Another way to go about it is to grind a semi circular or step chip breaker on the top of the tool parallel to the cutting edge with the corner of the grinding wheel; this will curl up the chips rather than having them come off stringy; this we were taught in machine shop class back in the early 1960s by our teacher who taught apprentice classes at our local navy yard after having served apprenticeship there himself.  When the feed is increased enough the chips will break in short curls rather than coiling like a spring.  These tools were used in Armstrong holders with the built in 15 degree back rake, but also work well in parallel holders.


----------



## mikey

ddickey said:


> Trying to grind
> 
> 
> 
> 
> 
> 
> 
> 
> 
> View attachment 235439
> 
> 
> 
> 
> 
> 
> 
> 
> 
> the back rake



You need some additional support under the bit. You might consider making an auxiliary table that drops onto the main table with a support ear on that right side. Once you have the support, all your issues will resolve.

Otherwise, the bit looks good! I can't see well but the cutting tip looks a bit sharp - did you stone a nose radius on it? If you do, the finish will improve.

You did an awesome job, Duane, especially for a first tool bit!


----------



## benmychree

Dan_S said:


> Looks like you need to make a U shaped wrap around rest.


Yes, that would help immensely!


----------



## ddickey

Yes I did Mike. 
Maybe a little more time with the diamond card.
Definitely will need to make a new table. This one is very thick also. When you angle the table a big valley opens up.


----------



## mikey

ddickey said:


> Yes I did Mike.
> Maybe a little more time with the diamond card.
> Definitely will need to make a new table. This one is very thick also. When you angle the table a big valley opens up.



Maybe make the nose radius a bit larger - it helps.

The belt to table distance should be about 1/16" or so. Your table should allow front-to-back adjustment. If it doesn't, make it so. This is a safety thing so an object you're grinding cannot tilt up and jam between the table and the belt; if it does, it will happen in an instant, before you can react. 

If you make a new table, make it with a protractor slot in it for when you need to grind an angle. Also make a drop on table with a support ear on the right side and a piece of stock underneath that fits the protractor slot. It takes only a second to lift such a table off and allows you to change belts without moving anything else.


----------



## ddickey

It does move forward and back. But as soon as you tilt the table down it touches the belt so you pull it back towards you. I'd say more like an eight or 3/16"  from the belt. This photo is not to good in showing that.


----------



## mikey

ddickey said:


> It does move forward and back. But as soon as you told the table down it touches the belt so you move it forward or back towards you. I'd say more like an eight or 3/16" even from the belt. This photo is not to good in showing that.



You might have to push the table into the belt and grind a bit of the bottom edge off to get the top of the table closer to the belt. At minimum, you want about 1/8", no more.


----------



## ddickey

mikey said:


> You might have to push the table into the belt and grind a bit of the bottom edge off to get the top of the table closer to the belt. At minimum, you want about 1/8", no more.


I like that idea.


----------

