Cutting down QCTP tool holders

We've touched on this subject. The BXA QCTP I bought for my Grizzly G0773 lathe / mill combo (12 x 27 swing & c - c) doesn't sit low enough on my cross slide. I couldn't begin to mill the holders as they are too hard. So it was suggested that I mount 1 up in the 4 jaw & starting from the center, cut it to size. OK, got it chucked up. What insert or cutter should I use?

 

Pick a negative rake insert like a TNMG, CNMG or WNMG, something that will take a beating. Were it me, I'd use the 100 deg. corner on a CNMG432. Of course, it may not be worth the expense of buying a holder and inserts for this job unless you're just looking for an excuse. If not, use what you already have and get the job done.

 

I needed to skim the bottom (and cut a step) in my 40 position style QCTP holders. I made up a mounting peg to hold the tool post (with a piece of threaded rod all the way out the back of the headstock to pull the mounting peg in securely) onto my drive plate. Then I just used the locking of the tool post to hold the holder. I trimmed ~8 holders (took about 0.1" off the bottom of each, cut the step, beveled the splines). There was nothing really special about the tooling - somesort of generic TNMG for the facing and CNMG in a carbide shank boring bar. It all worked out great (getting a nice finish took a few tries). For the primary tools/holders I skimmed them just enough so that the holder sits right down on the compound - no adjustment needed (I took the adjusters off) - afterall the tool will likely stay in that holder as long as I own the lathe.

The point being that while the holder material is pretty hard / tough material, skimming the holders was not a big deal.

Let us know how you make out. David