Models for grinding HSS Lathe Tools

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

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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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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.
 
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,
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.
 
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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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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.
 
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
 
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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