- Joined
- Feb 24, 2018
- Messages
- 1,044
Yep, I've milled & turned China holders. They're not that hard. China hardened is not the same as USA hardened.
Yeah, either hardened too little or hardened too mush, Chinese hardening can be a real crap shoot.
I bought some cobalt drill bits from Graingers, they had a rainbow hue to them, the 3/8” rolled off the table, hit he floor and shattered into hundreds of pieces. I thought that was strange, so I purposely let the 5/16” bit, roll off the table, it hit the floor and shattered.
I took a different bit from one of the other serviceman’s box, the bit caught, the chuck kept rotating about a turn and boom the spiral in the bit was gone, twisted like a Twizzler. I show it to the other guy, he said yeah, he has 3 or 4 more, that that happened to.