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Models for grinding HSS Lathe Tools

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mikey

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#1
In a recent thread by @Darkbluesky, http://www.hobby-machinist.com/thre...tools-ideas-of-what-to-buy.62043/#post-511618, @ttabbal joked about sending me blanks to be ground into lathe tools ... he was joking! But it got me to thinking ... yeah, I know it's not a good thing when Mikey gets to thinking ... but it got me thinking that reading about how a tool is ground and having a decent tool in your hands that you can see and touch are two different things.

So, what if I ground a set of tools from 3/8" mild steel keystock (just to discourage some bozo from actually trying to cut something with the models) so people could hold it in their hands to look at. You could use them to plop onto your tool rest to see what the rest angles should be and maybe how your hands have to align to grind the tool. You could also buy some keystock and duplicate them for a permanent reference, and then pass them on to the next guy who wants to have a look.

I'm thinking of making THREE sets of these model tools and mailing them out to guys who are interested. We would need to figure out a list if there are more than three guys interested in seeing them, and YOU GUYS need to sort out how to keep track of these things. I would guess one to two weeks of holding time per person would be reasonable and the guy who has them would pay to flat rate ship it to the next guy on the list. Naturally, the only guys who can get on the list would be members of the HM forum.

As to which tools to include in the set, I'll leave that to you guys. We can discuss it here and see if we can come to some consensus. I will probably write a set of notes with details on how each tool is ground and why the angles are what they are and how you can modify them to better suit your needs; these notes would be posted to this thread.

I don't know if this is of interest to anyone but on the off chance that it is, let's talk about this and see if we can make it real. I'll spring for the keystock, grind the models and send them out. After that, you guys need to sort out how to get them distributed. The last guy on the list can hang onto them until some other HM member contacts them or you can send it back to me so I can do the same.

Let me be very clear about one more thing. The models will be of tools as I grind them for use in my shop on my lathe(s). It is one way, not necessarily the right way or the only way. My hope is that it will help you to find your own way of grinding tools that work for you.

Thoughts?

Mikey
 

tweinke

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#3
I think that would be an awesome idea. Possibly grind a standard LH, RH, threading tool, and ??? I for one would be very interested in actually being able to touch a tool that has the potential to work instead of guessing from pictures.
 

mikey

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#4
I think that would be an awesome idea. Possibly grind a standard LH, RH, threading tool, and ??? I for one would be very interested in actually being able to touch a tool that has the potential to work instead of guessing from pictures.
Okay, thanks, Todd. Are you thinking a general purpose RH tool, a roughing tool or ... ? I was thinking maybe a RH general purpose tool, a RH knife (facing) tool and a threading tool. A LH version is just a mirror image that you can sort out easily. I'm okay with whatever you guys feel the need for.
 

tweinke

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#5
I like your thinking, much better then my newbie thoughts. only reason I mentioned a LH tool was for some it may be hard to grasp the mirror image thing. I really have enjoyed your posts on tool grinding and can grind a tool that will cut but to be able to touch a proper tool and see it in my own hands would just be cool. I am in the process of getting ready to build a belt grinder with tool sharpening as the primary reason. I hope more guys chime in on this soon!
 

mikey

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#7
I like your thinking, much better then my newbie thoughts. only reason I mentioned a LH tool was for some it may be hard to grasp the mirror image thing. I really have enjoyed your posts on tool grinding and can grind a tool that will cut but to be able to touch a proper tool and see it in my own hands would just be cool. I am in the process of getting ready to build a belt grinder with tool sharpening as the primary reason. I hope more guys chime in on this soon!
Thanks, Todd. Yeah, I think it might be helpful to actually hold a tool in your hand that, if reproduced in HSS, will actually work the way it is intended to work. All of us, to some extent, are visual learners and if we do this then I hope it works out okay.

As for the mirror image thing, I'll write it up so that you can't possibly misunderstand how it is done. I'm listening, Todd and will do what I can to make this work for you.
 

Ken from ontario

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#8
Mike, the idea is great , I would love to own a RH facing/turning bit that you have ground but I'll be honest with you, for a newbie like myself , this bit will be something to look at and compare other bits with periodically as a reference piece, it is not something I could let go after a short while. if you remember I bought a "training set" from LMS but it is a basic set and I still would like to have a single bit made by you for my own personal use.
I know it may sound selfish but that's how I feel about it.
 

Groundhog

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#9
I think that is a great idea. I've been grinding my tools for some time but have fallen into bad habits resulting in non-standard tools (my own special misshapen grinds). They seem to work, but I'm not sure why.
It would be nice to compare those to a properly ground tool.
 

mikey

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#10
great idea Mikey.
if you see and know what a good example of a hand sharpened tool is, it is much easier to reproduce one :grin:
Thanks, Mike! For you experienced guys, this may not be of interest but I remember all too well what my tools looked like when I started - they were pretty bad!!!

I actually had a set of pre-ground tools from Sherline and it helped but what I didn't know was that those tools were ground to the typical geometry found in a tool angle table and I couldn't take a decent cut with them on my Sherline lathe. A 0.020" deep cut in 12L14 steel resulted in chatter and it took a long time, experimentation and frustration to figure out how a tool cuts. Now I can triple that 0.020" deep cut in 12L14 mild steel with my Square Tool and have no chatter on a Sherline lathe; the only thing that changed is the geometry of the tool. I will say that those original Sherline tools allowed me to hone my profanity skills, though!
 

mikey

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#11
Mike, the idea is great , I would love to own a RH facing/turning bit that you have ground but I'll be honest with you, for a newbie like myself , this bit will be something to look at and compare other bits with periodically as a reference piece, it is not something I could let go after a short while. if you remember I bought a "training set" from LMS but it is a basic set and I still would like to have a single bit made by you for my own personal use.
I know it may sound selfish but that's how I feel about it.
Ken, thanks for being honest. Let's you and I discuss this in a PM - contact me when you have time. I'm partly responsible for egging you on about being lathe-less so I feel some responsibility ... ;)
 

mikey

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#12
I think that is a great idea. I've been grinding my tools for some time but have fallen into bad habits resulting in non-standard tools (my own special misshapen grinds). They seem to work, but I'm not sure why.
It would be nice to compare those to a properly ground tool.
Thanks for your input, Groundhog. I plan to grind modified tools that work for me. They will not be standard tools that you can grind from the data found in any tool grinding table. The models I have in mind should work better than a standard geometry tool but whether they are "proper", I don't know.
 

thomas s

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#13
Mikey, Thank for taking the time to do this. I think it is a great idea count me in. Thomas S.
 

DHarris

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#14
Brilliant idea Mikey!!! and your write-up of the tools / grinds will be invaluable to close the loop for all of us newbies!!

Well done Sir!

Dave Harris
 

ttabbal

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#15
I think this is a great idea! Thanks for offering to do something like this. I may have to order some blanks even without yet having a lathe just to have some grinding time with a reference in hand.

I may have to start a thread about grinder upgrades. My HF grinder is kinda crappy.. But with some work on the rest it might be usable to start with.
 

mikey

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#16
Okay, there seems to be some interest. Now we need to decide which tools to include in the set. I agree with Todd that a RH turning tool and threading tool would be a good idea but I'm not married to the idea. What do you guys think?

I think a knife tool would be a good addition but since you can face with a turning tool, it might not be what you want. Just know that a knife tool will face better than a turning tool and is excellent for thin work sizing cuts. It will take a whisper-thin cut on a small diameter work piece and it also works pretty good for chamfering. Since facing is a basic lathe operation it is a good tool to know how to grind but its up to you guys. Let me know.
 

Groundhog

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#17
Thanks for your input, Groundhog. I plan to grind modified tools that work for me. They will not be standard tools that you can grind from the data found in any tool grinding table. The models I have in mind should work better than a standard geometry tool but whether they are "proper", I don't know.
Actually I was being sarcastic. I have been grinding my tools improperly (although they seem to work most times!) and would like properly ground tools to compare my poorly ground tools with. I need to break my bad habits.
 

mikey

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#18
Actually I was being sarcastic. I have been grinding my tools improperly (although they seem to work most times!) and would like properly ground tools to compare my poorly ground tools with. I need to break my bad habits.
Mike, I hope my models meet your expectations. If they help you in any way then I'll be happy but don't expect too much - they're just turning tools.

I keep saying this but nobody can possibly make an uglier tool with more facets than I did as a beginner. I thought I tossed those early tools but I may have some of my early efforts somewhere in this shop; if I can find them I will show them so you know I'm not kidding.
 

ttabbal

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#19
Obviously, I'm coming at this with little practical knowledge... I would like to have an example of at least the most common tools. Turning, threading, and facing being the most obvious. The knife tool sounds useful.

One thing that comes to mind is surface finish. It sounds like a tool with a larger radius gives a better finish. Rough and finish versions of one of the tools might be useful.

Perhaps number them with matching examples from written info or times in the video? So we can read/watch while looking at the tool? I don't want to make a lot of work for you, so feel free to do whatever. Just thinking out loud as a beginner.
 

Rockytime

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#20
Thanks, Mike! For you experienced guys, this may not be of interest but I remember all too well what my tools looked like when I started - they were pretty bad!!!

<SNIP> Now I can triple that 0.020" deep cut in 12L14 mild steel with my Square Tool and have no chatter on a Sherline lathe; <SNIP>

I've used my Sherline for 20 years and can't even imagine a .060 depth even in brass. How do you do that?
 

mikey

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#21
Rockytime, just my general purpose square tool will take a 0.050" deep roughing cut in 12L14 on my Sherline lathe as shown below:

CRW_2883.jpg

My tool for mild steel has a bit more side rake and will take 0.060" in a single pass without chattering.

EDIT: I should answer your question as to how I do that. I increase the relief and side rake angles but keep the back rake angle near baseline. This reduces cutting forces significantly while also focusing those cutting forces at the forward area of the side cutting edge. A Sherline lathe is pretty light and cannot handle the cutting forces a standard geometry tool produces but give it a little help with the geometry and it becomes capable of much more. The same is true for all lathes, not just a little Sherline.
 
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mikey

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#22
Obviously, I'm coming at this with little practical knowledge... I would like to have an example of at least the most common tools. Turning, threading, and facing being the most obvious. The knife tool sounds useful.

One thing that comes to mind is surface finish. It sounds like a tool with a larger radius gives a better finish. Rough and finish versions of one of the tools might be useful.

Perhaps number them with matching examples from written info or times in the video? So we can read/watch while looking at the tool? I don't want to make a lot of work for you, so feel free to do whatever. Just thinking out loud as a beginner.
Okay, a turning tool, facing tool and threading tool. This covers most general lathe operations. Anything else?

By the way, finishes are affected by the nose radius, relief angles and back rake. We'll make that clearer as we go along.

I never made a video, although I've thought about it.
 

Z2V

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#23
Mikey,
Very generous of you to offer to do this. I'm very interested in seeing your tools so count me in. Do you use a jig or do you grind free hand? Do you use a bench grinder or belt? I have an 8" bench grinder and I'm also in the process of building a belt grinder.
Great idea, thank you
 

mikey

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#24
Mikey,
Very generous of you to offer to do this. I'm very interested in seeing your tools so count me in. Do you use a jig or do you grind free hand? Do you use a bench grinder or belt? I have an 8" bench grinder and I'm also in the process of building a belt grinder.
Great idea, thank you
I use a belt sander but I cheat - I have a really good tool rest. The tool is otherwise ground "free hand" without a jig of any kind. You can do the same thing on a bench grinder provided you can get the tool rest at the right angles. That's why I thought models might help folks see the rest angles a bit better.
 

Aukai

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#25
I always thought I was born too late, looks like I have good timing for this opportunity. This is an awesome offer, I will donate blanks. I would like to take part, I have a new grinder, and some new AL wheels I'd like to break in, not wear out on the first try. LOL
 
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mikey

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#26
I always thought I was born too late, looks like I have good timing for this opportunity. This is an awesome offer, I will donate blanks. I would like to take part, I have a new grinder, and some new AL wheels I'd like to break in, not wear out on the first try. LOL
No need to donate anything. I already have the 3/8" keyway stock so it's no problem. I will order some new belts for my sander and get them done once we figure out which tools the guys want to see.
 

Z2V

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#27
I would be particularly interested in the knife for facing and a threading tool in addition to general turning. Could you possibly show the difference between a roughing and finishing tool also.
Would also like to see your tool rest if you would care to share a pic or two. I'm looking for ideas for my own belt grinder.
Again, thank you
 

mikey

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#28
I would be particularly interested in the knife for facing and a threading tool in addition to general turning. Could you possibly show the difference between a roughing and finishing tool also.
Would also like to see your tool rest if you would care to share a pic or two. I'm looking for ideas for my own belt grinder.
Again, thank you
You can see my grinder and tool rest here: http://www.machinistblog.com/modifying-a-craftsman-2-x-42-inch-belt-sander-for-tool-grinding/#more-5349.

You should also look at the thread by @Alan H on his tool rest: http://www.hobby-machinist.com/thre...and-work-table-upgrades-lots-of-photos.61968/

@ddickey also has a 2x72 grinder he is setting up for tool grinding; you can PM him.

As for roughing and finishing tools, if you intend to use separate tools for all three common lathe operations (roughing, finishing and facing) then we can do that. Having separate tools was popular before we had quick change tool posts and all three types were used with the tool shanks perpendicular to the work. The advent of the quick change post changed that and now most guys prefer to use a general purpose tool to rough and finish.

The relief and rake angles are different on a general purpose tool vs the older style tools and you have to understand how they differ because general purpose tools are a compromise. In order for a single tool to handle heavy cutting loads and then turn around and take fine sizing cuts with a fine finish is a tall order. And yet, we can come pretty close if we add a little more side and end relief, add in a bit more back rake and increase our nose radius just a little bit. These changes are subtle but make a huge difference in how the tool performs.

You also have to bear in mind that no tool cuts all materials equally well. A general purpose tool is really a shape, not a designated tool with specific angles. You can use the same shape but have relief and rake angles that are optimized for a given material class and that tool will work better for that material class.

Rather than grind a tool for every material class, I'll grind a Square Tool. This is a general purpose tool that will work pretty well with most materials commonly used in a hobby shop. If you work with a particular kind of material a lot then it will be better to change the angles on the tool to better suit that material. For example, a general purpose tool for aluminum will have larger relief angles, more side rake and way more back rake than a Square Tool will have but the overall shape of the tool will be the same. The aluminum tool will typically have a slightly larger nose radius than one for say, steel; this gives us a mirror finish that a smaller nose radius would not do as well.

As you can see, there is a lot to grinding a good tool. The thing is, once you see how the table angle is set to grind a relief angle on my model then it is a simple step to know that increasing that angle a degree or two more will reduce cutting forces further and allow the tool to cut with greater ease. Similarly, once you have a solid idea of how the side rake is ground then that really opens the door to changing how your tool can cut with lower cutting forces and cutting temperatures. I can tell you how to do it but if you also see the model so you can set the actual table angle then that makes it simpler to understand. I think that's been the missing link for a lot of guys and is the key reason for doing this model tool thing.

What I intend is to write an article that goes with the model tools. I will show how each is ground and why each angle is chosen. I will also tell you when to change the angles, how to change them and why. Once you are clear on this stuff it is a simple step to deciding how to grind a tool that will do exactly what you want it to do.

I don't know how much you know about tool geometry or tool grinding, Jeff, so pardon me if I'm insulting you by referring you to an article that I wrote that might make all of this clearer. You can see it here:
http://www.machinistblog.com/?s=belt+sander&submit=Search. Its in three parts but all the articles are on that page. Look it over and we can go further if you need to.
 
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