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Vertical shear lathe tool

Like this?

20230412_091727.jpg
 
John Conroy said:
Like this?

View attachment 33506
Click to expand...

Yup. The wool is a clear sign that your tool is working.

I don't find that the grind matters much. It either works or it doesn't. But I usually prefer a steep angle on the edge.

Another trick to know is that the edge can be adjusted up or down as the edge wears. So one grind lasts a very long time.

Your wool looks a little big to me but the finish is a better guide.

You could try increasing the speed and reducing the feedrate. Or even just the feed rate.
 
Been using this idea and concept for a while now, Only way I knew how to make tenths passes and get mirror finishes in gummy metals.
Now I just opt for the CCGT DCGT tooling and settle for almost as good.

I never made .001 passes with that tool though, Never more then .0005
Thanks for posting!

Gluck
 
I have been using Carbide inserts without issues, wish I could tell you what I'm doing different to share the information. Set up I guess.
 
I have been using DCMT inserts too but need to take a much larger depth of cut to get a good finish. If I need to take a very light cut, nothing I've tried matches the finish of the shear tool. Experimenting with angles I've tried between10 degrees and 20 degrees from vertical. 10 seems to give a better finish and the edge needs to be razor sharp.
 
John Conroy said:
I have been using DCMT inserts too but need to take a much larger depth of cut to get a good finish. If I need to take a very light cut, nothing I've tried matches the finish of the shear tool. Experimenting with angles I've tried between10 degrees and 20 degrees from vertical. 10 seems to give a better finish and the edge needs to be razor sharp.
Click to expand...

That's exactly my sentiments. I can take a few tenths with a shear tool and still have a decent finish. It's tough to do that any other way than grinding. My spindle motor based tool post grinder works, but I'm not fond of using it. Perhaps that will come with time.

But the other use for a shear tool is getting a nice finish on materials that are otherwise hard to cut nicely.

I confess that I don't know what angle I use. I do it so often that I just have a feel for what it needs to look like. I'll measure one of mine next time I'm out at the shop. If I had to guess, I'd agree that it's around 10 degrees or so.

I also totally agree that it must be razor sharp! I usually grind, then fine grind, then stone, then polish with rouge on a leather strop wheel. It's a lot of work to get a nice edge, but the length of the edge makes it possible to use it for a very long time before it needs resharpening just my moving the tool up or down to get a fresh portion of the edge.

I forgot to mention earlier that it's the nature of a shear tool that it doesn't need to be on center cuz it's always on center! Vertical adjustment is only done to get a fresh edge.
 
Susquatch said:
That's exactly my sentiments. I can take a few tenths with a shear tool and still have a decent finish. It's tough to do that any other way than grinding. My spindle motor based tool post grinder works, but I'm not fond of using it. Perhaps that will come with time.

But the other use for a shear tool is getting a nice finish on materials that are otherwise hard to cut nicely.

I confess that I don't know what angle I use. I do it so often that I just have a feel for what it needs to look like. I'll measure one of mine next time I'm out at the shop. If I had to guess, I'd agree that it's around 10 degrees or so.

I also totally agree that it must be razor sharp! I usually grind, then fine grind, then stone, then polish with rouge on a leather strop wheel. It's a lot of work to get a nice edge, but the length of the edge makes it possible to use it for a very long time before it needs resharpening just my moving the tool up or down to get a fresh portion of the edge.

I forgot to mention earlier that it's the nature of a shear tool that it doesn't need to be on center cuz it's always on center! Vertical adjustment is only done to get a fresh edge.
Click to expand...
does that company that makes the HSS inserts make a shear tool type insert? Or do I need to make my own ground tool
 
I used to use a shear tool all the time & stopped for some reason, not really sure why. For one thing I was turning more sh*t grade 1018 that wasn't pretty with any tool. It did work well & grinding 2 simple angles in HSS that aren't super critical is trivial & quick. The shear/insert difference wasn't as pronounced with say 12L14. On aluminum my inserts are very sharp they cut pretty similar even on light DOC. But I've been thinking of pulling out the shear tool again for materials like stainless. Depending on the SS alloy, it likes to work harden & can be miserable in other respects. I get along fine with 303 but some of the others can be challenging. I have some bearing fits coming up in next project & probably worth revisiting.

I think shear is a bit of misnomer because a regular cutting tool is shearing metal too. I think its putting the cutting surface a more favorable plane of action, drawing the chip over a longer length & with less secondary effects. I visualize it like wet snow shoveling obliquely (where snow its piling up, more friction, more load, more digging in...) vs set at a high angle where its curling off to the side more efficiently & controlled. Not sure if that's the right way to look at it. There are woodworking analogies to this as well where a different angle + very sharp edge + shallow DOC makes for better cutting conditions.
 
TorontoBuilder said:
does that company that makes the HSS inserts make a shear tool type insert? Or do I need to make my own ground tool
Click to expand...

I've never seen them for sale. I've always ground my own.

It's more work than most bits, but the resulting tool lasts forever and is also very easily resharpened.

The companies I have bought HSS inserts from don't sell shear tools. I've never seen them for sale anywhere. Perhaps they are, but I've never seen it.
 
PeterT said:
I think shear is a bit of misnomer because a regular cutting tool is shearing metal too. I think its putting the cutting surface a more favorable plane of action, drawing the chip over a longer length & with less secondary effects. I visualize it like wet snow shoveling obliquely (where snow its piling up, more friction, more load, more digging in...) vs set at a high angle where its curling off to the side more efficiently & controlled. Not sure if that's the right way to look at it.
Click to expand...

I think of it a bit differently. (why aren't you surprised....LOL!)

I think of a regular tool as plowing (your recent video showed the effect perfectly).

But I visualize a shear tool working like a pair of tin snips shearing off a very thin wire.
 
Susquatch said:
I've never seen them for sale. I've always ground my own.

It's more work than most bits, but the resulting tool lasts forever and is also very easily resharpened.

The companies I have bought HSS inserts from don't sell shear tools. I've never seen them for sale anywhere. Perhaps they are, but I've never seen it.
Click to expand...
maybe I can combine a HSS insert with the technique from the video John Conroy posted and get better results than that fellow did
 
PeterT said:
But I've been thinking of pulling out the shear tool again for materials like stainless. Depending on the SS alloy, it likes to work harden & can be miserable in other respects. I get along fine with 303 but some of the others can be challenging. I have some bearing fits coming up in next project & probably worth revisiting.
Click to expand...
I've had really nice results with "Crobalt" hss in my diamond tool holder for stainless steel. I confess that I did not know the grade/spec of the ss I've turned in most cases.
20230414_111408.jpg
 
TorontoBuilder said:
maybe I can combine a HSS insert with the technique from the video John Conroy posted and get better results than that fellow did
Click to expand...

If that works, I'd be very interested in seeing how you did it. In fact, it would probably be worth its own thread cuz it's not a very common way to do it.

Most of the time I just grind the end of a 1/2 inch hss tool blank.
 
DPittman said:
I confess that I did not know the grade/spec of the ss I've turned in most cases.
Click to expand...

Wanted to put a Laughing icon on your post.

That sounds like me too!

That's one of the nice things about a shear tool. Who cares what the mystery stock is? It will work! LMAO!
 
John Conroy said:
I have been using DCMT inserts too but need to take a much larger depth of cut to get a good finish. If I need to take a very light cut, nothing I've tried matches the finish of the shear tool. Experimenting with angles I've tried between10 degrees and 20 degrees from vertical. 10 seems to give a better finish and the edge needs to be razor sharp.
Click to expand...
Did you men DCGT vs. DCMT ?
 
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