Models for grinding HSS Lathe Tools

[Aukai]

I have suffered with this, the right diamond plates, the right honing fluid, and relax, your not grinding the bit. It's a soft hone, and trying to be flat. Yes it's easier written than done, but it will come.

 

[mikey]

Caveat: In this thread, Mikey describes using a belt grinder with a hard, flat platen, and hand honing on flat stones, to achieve sharp tools. I expect that achieving it requires some combination of talent and practice.

The key advantage of a flat platen on a belt sander is that it produces flat faces that register well on the face of a flat stone, like a diamond stone. This makes it simple to hone each face, although I admit the end face can be harder because it is smaller so there is less real estate to register solidly on the stone.

There is no trick to honing. Just take your time and focus on getting rid of the grind marks while keeping the involved face flat. i prefer to put cutting pressure on the pull stroke and i go slow so I don't lose the register of the face on the stone. I do all three faces like this, including the top face, and have no real issues doing so. My edges cut like scalpels when I'm done.

It may be true that i have no issues honing tools because I've done hundreds of them. If that is true then it should be true for most everyone so practice - you won't improve without working at it.

 

[Grader Johnny]

First go at grinding and the new grinder goes well in my view 8in 1HP spinning 1450rpm which yes is slow but give me more time to get it right.
Cheers Johnny

 

[Grader Johnny]

That’s the first one done.

 

[Grader Johnny]

As close as I could get to 60 degree threading tool. Now I stuffed up with the turning tool as it only has 10 degrees on the tool rest

 

[ttabbal]

Those look good! You're heading in a good direction. Don't overthink the angles, the rest being a few degrees off won't make it not work. Perhaps less efficient for some materials, but it'll cut. Heck, try both and see what your setup likes best.

 

[Grader Johnny]

Those look good! You're heading in a good direction. Don't overthink the angles, the rest being a few degrees off won't make it not work. Perhaps less efficient for some materials, but it'll cut. Heck, try both and see what your setup likes best.

Thanks ttabbal
Trial an error is the way to go. Just waiting to get some round bar to do some projects.

 

[Karl A]

The key advantage of a flat platen on a belt sander is that it produces flat faces that register well on the face of a flat stone, like a diamond stone. This makes it simple to hone each face, although I admit the end face can be harder because it is smaller so there is less real estate to register solidly on the stone.

There is no trick to honing. Just take your time and focus on getting rid of the grind marks while keeping the involved face flat. i prefer to put cutting pressure on the pull stroke and i go slow so I don't lose the register of the face on the stone. I do all three faces like this, including the top face, and have no real issues doing so. My edges cut like scalpels when I'm done.

It may be true that i have no issues honing tools because I've done hundreds of them. If that is true then it should be true for most everyone so practice - you won't improve without working at it.

I tried the opposite last week: hand honing the ground face of a 3/16-inch tangential (AKA diamond) tool bit that had a very-hollow grind: I ground the face using a 1-inch diameter grinding wheel on a Dremel rotary tool. I didn't suceed in hand honing it evenly and flat. Other people recommend hollow ground surfaces for honing, but at least for me at this time it is not a panacea.

I find that I am able to hand hone the side faces of a tangential tool bit by pulling the tool bit along its long axis. I think that this little success confirms what you suggested: that hand-honing flat faces is a matter of degree of difficulty.

I can use my modified/improved 2x42-inch belt sander to grind tangential tool bits that end up with your recommended rake angles for cutting different materials. I set the table tilt angle to achieve the desired side rake angle, and I set the protractor to achieve the desired back rake angle (adding the tilt angles of the tool holder to the table tilt and protractor). I can avoid needing to hand hone the ground face by grinding with finer and finer belts, up to 800 aluminum-oxide grit.

 

[Karl A]

After having and using a 55-degree carbide-insert tool and an HSS RH knife tool for two years, I realized only this week that the tools are basically carbide and HSS versions of the same tool. The 55 degrees of the carbide insert is the same thing as the 35 degree end-cutting-edge angle of the HSS tool. One difference between them is that the carbide-insert tool has a few degrees of negative side-cutting-edge angle.View attachment 420318

Two other correspondences between insert tools and ground HSS tools are:
- 80-degree diamond insert tools and HSS tangential tools
- neutral-hand 55-degree and 35-degree diamond insert tools and HSS round-nose tools.

 

[roghmc]

OK, I'm still learning about making HSS tools, but have already learned that even with good grinding wheels (I have two dedicated grinders with various grits of Norton 38A and 32A wheels) that for some, there is a LOT of material to be removed. I've seen some YouTube guys making rough cuts with angle-grinders to get closer to the end shape with less grinding wheel time and wear and I happen to have a pretty decent old Ryobi 4" angle grinder sitting on the shelf collecting dust I could dedicate to this. So, my question, what is the ideal (might as well pick ideal(ish) since I'll be buying some wheels either way) type of wheel to use. Flat or dished/27? Grit? Material? I see some listed for Ferrous and Stainless. Is that good enough for HSS, or is there something better? Thanks in advance for any pointers.