Chipbreaker handedness versus tool holder handedness

[ericc]

I have been getting interested in using inserts for my lathe. HSS works fine, and I have plenty of it, but I got some large negative rake triangular inserts. Earlier, I posted about my surprise when I could find a narrow range where they would work with a cobbled together toolholder. Anyway, they're no use otherwise, and it is better to go out to the shop and give them a try than to endlessly surf web (which is no good for you in the long run).

After some initial success, instead of getting recommended tools from Aliexpress, Shars, or Ebay, I went to a neighbor who was liquidating and bought a grab box of cutting tools. Inside this box were two insert toolholders. One was a positve rake trangular insert holder, and the other held what looked like 3/8" IC TNMG inserts. It was a little confusing, though, since this toolholder had what appeared to be a right hand chipbreaker insert in a left hand toolholder. I tried searching on the web, but all I found was "use R chipbreaker inserts with right hand tools and use L chipbreaker inserts with left hand tools; the insert shown has an R chipbreaker." This tool seems to be switched. I couldn't find any simple illustrations. Is this on target?

 

[T Bredehoft]

This insert is meant to cut from right to left, standard lathe work. The holder you have it is is meant to hold an insert that will cut from left to right. This insert will not cut (you know this) left to right, and only moderately right to left. It will be shaving, rather than cutting (in normal fashion)

 

[benmychree]

Tom said it all!

 

[ericc]

Thank you fellas for confirming what I thought. I was having a terribly hard time searching up something on the Internet, and my Sandvik cutting tools guide did not mention anything. Could this have been set up for facing towards the right (backwards from regular facing)?

This holder is still of value to me since I can study the clamp and pin arrangement in more detail.

 

[T Bredehoft]

Thanks, Ben.

Could this have been set up for facing towards the right ?

Yeah, but you'd want to lean the holder toward the right a couple of degrees so the insert wouldn't drag on the finished cut. Not the intended purpose for the insert. That would be like shaving with the end of the razor blade. (I know, no one knows what a razor blade is any more...)

 

[ericc]

...

Yeah, but you'd want to lean the holder toward the right a couple of degrees so the insert wouldn't drag on the finished cut. Not the intended purpose for the insert. That would be like shaving with the end of the razor blade. (I know, no one knows what a razor blade is any more...)

That is absolutely correct. I even tested it out, and it indeed rubs. The fellow probably just put the wrong insert in there. The odd thing is that in all the boxes he gave me, there was no correct insert. There was a boatload of wrong ones, nearly all of them name brands. The temptation is very strong to just go buy some fitting tool holders on EBay. Lots of fiddling to do. Still, better than wasting time.