Shop-made bench block, made from some unknown alloy of tool steel. Didn’t realize it was tool steel until it work-hardened badly after facing both ends and trying to drill the holes, which wound up destroying a few drill bits. Annealed it in a tiny 350 watt pottery/glassware kiln for several hours. Boring out the recess was a lesson in frustration, no matter what I tried it just wouldn’t cut well, and the chips were a nightmare (as seen in the 4th shot).

Carbide inserts finally arrived for the holders we have at ENTS (www.ents.ca) so I was able to finish the OD today using a 5/8″ bolt as an arbor with a 1/4″ nut & bolt as a drive dog. I’ll be damned if I was gonna file off that rock-hard crusty outer layer from the annealing process by hand. (”oh, it’ll just flake right off easily!” a few people told me. Yeah, and I’m the fuckin’ space pope. Even a wire wheel on the bench grinder didn’t take it off easily.)

Brand new carbide leaves such a nice finish, don’t you agree? 3-1/4″ diameter, 550 RPM (~465 SFPM), .030″ DOC, .005″ IPR. The spray of chips it peeled off was impressive! I wish I had gotten video, but I didn’t think about it until halfway through the cut, and I only needed the one pass. If only the inside diameter machined so easily… grrr!