Shear tools for lathe work.

**crazypj** · Sep 28, 2017, 06:42 PM

When I was training, I used something similar but MUCH larger.
I was pretty interested in making 'stuff' and used it on 1-1/2" stainless steel clock part. (Vic, the instructors hobby was clock making) I also got to make a 'load' of stainless 'rivets' from 1/8" welding rod whic wasn't much fun. ('conventional' tooling for that)

Almost sure instructor called it a shriving tool (or something very similar?) It was a 3/4" piece of tool steel mounted with one end down towards headstock at a shallow angle (15~20 degrees?) with 'back end' pointing out and up. (almost like a wood lathe tool rest?) Zero setting up as te edge would be 'on centre' somewhere along it's lengthno grinding just two sides polished a bit with oil-stone. Can't remember what sort of fixture held HSS in place but it wasn't a welded up 'homemade' part
This is the closest thing I've seen to the 'unknown' tool I used but tis set up has much steeper angles.
The only disadvantage was it needed quite a lot of clearance at front end and couldn't be used close to chuck

**Cascao** · Oct 4, 2017, 07:54 AM

Clever approach in carbide shear tool. Will try it. Definatelly.

Shear tools are greath when you need remove small amounts of material too. Conventional tools have a grab/no grab behavior sometimes leading to incosistencies in amount removed and tight tolerances can be tricky.

Below a comparasion I did with shear tools vs conventional tools.

**tonyfoale** · Oct 4, 2017, 08:57 AM

Originally Posted by Cascao

Below a comparasion I did with shear tools vs conventional tools.

Great video. I did similar tests, but mainly on aluminium which is the main metal that I work with, although I did some tests with 4140. I videoed none.

**Canobi** · Mar 19, 2018, 02:49 PM

Yay! Thanks to your post showing shear tool geometry, I've realised I didn't balls up my first attempt at grinding a right hand turning tool, I was in fact making a shear tool without knowing it. Just as well as it was crap at being right hand turning tool but I kept it as a reminder. And to think, all this time I've been striving for a smoonth finish on my work and all I had to do was rotate the bit 90° in the holder

**tonyfoale** · Mar 19, 2018, 03:12 PM

Originally Posted by Canobi

Yay! Thanks to your post showing shear tool geometry, I've realised I didn't balls up my first attempt at grinding a right hand turning tool, I was in fact making a shear tool without knowing it. Just as well as it was crap at being right hand turning tool but I kept it as a reminder. And to think, all this time I've been striving for a smoonth finish on my work and all I had to do was rotate the bit 90° in the holder ]

It is not strictly required for turning but if you make the front of the cutting edge vertical (assuming that your lathe is level) then the tool height becomes unimportant and you can change it without changing workpiece diameter. So when you get some wear on the tool just raise or lower it a bit. Thus extending periods between sharpening.

**Canobi** · Mar 19, 2018, 05:01 PM

Will do and thanks again

I thought I'd give the shear tool a whirl on the shank of an arbour I'm making as its a shade oversize and was giggling like a little schoolgirl while taking the few passes needed to bring it bang on size, neither which were more than .01mm:

Although not pictured, I have been using a centre in my tailstock while working on this piece but it's nice to see all the effort I've put into referbishing my old lathe is paying off, just sorted the last major issue yesterday by making my own flat belt, the teeth connectors that the previous one had was causing undue vibration and it was showing in the work, so this was a real treat for me

**Denis G** · Mar 31, 2018, 06:14 AM

I saw the video, and although it is an interesting tool, it wasn't what I expected from its name. "Shearing" is usually used to describe a cutting action, so I was expecting to see something like what a parting tool does. It seems that the process for this tool is more like "burnishing."

**tonyfoale** · Mar 31, 2018, 08:23 AM

Originally Posted by Denis G

I saw the video, and although it is an interesting tool, it wasn't what I expected from its name. "Shearing" is usually used to describe a cutting action, so I was expecting to see something like what a parting tool does. It seems that the process for this tool is more like "burnishing."

Denis,
I didn't invent the name, that is in common use for this type of tool.
The action is far from burnishing, it is a true cutting action, as I am sure that anyone who has used one would testify to.

**Rorschach** · Mar 31, 2018, 09:10 AM

A very useful tool that has saved me many times. I have a facing and a side cutting bit ground up. Gives an almost polished finish on brass too.

**olderdan** · Mar 31, 2018, 12:01 PM

Canobi,
For some years now I have been running my SB lathe with an inside out poly v belt which is super smooth and quite cheap to buy. I have tried scarfed leather and flat grinding belts but this is the best.
I like flat belt drive as it is quiet and has saved a few tool breakages (works like a fuse).