Machining out the ID on 24 bearings

[cathead]

Back in the 70's an old machinist took a bandsaw blade, and with a hand grinder, put negative rake on the teeth of half the blade. I thought he was nuts. He then took a bar of hard Ampco bronze and started cutting a piece off of it. The unmodified part of the blade would not touch the hard Ampco but the modified section cut through like a hot knife through butter! He told me that the same thing works for turning hard materials.
I don't know the physics of it, but I've used that trick many times since and taught it to many others after that.
Richard

When I machined those bearings, several things were tried. The most effective thing was to machine with the tool a little above center.

 

[woodchucker]

I don't believe that to be true Robert. there are many wnmg, cnmg (current common) cutters with negative rake.