- Joined
- Jan 20, 2018
- Messages
- 5,637
I was tapping a bunch of blind 10-32 holes in some hardened material. Not Rc 60 hard, but Rc 40-45 anyway. I was being very careful, lots of Tap Magic, lots of forward and back, lots of sweat. Suddenly, TINK! NOOOOOO........!!!!! There were some shards of the tap sticking up, but of course they broke off. I then went after it with punch and hammer, hoping to break it up. No joy. I let it sit overnight while I contemplated my situation. Today I decided to try making a spade drill from the shank of a broken 1/4" carbide endmill. First I started rough grinding it on the SC wheel on my bench grinder. Then I decided to get smart. I chucked it in my cordless drill et voilá, crude centerless grinder. I didn't put a lot of effort into the point, just a simple chisel edge, raggedy and off-center. It took multiple attempts and trips back to the grinder, chipping the end then running out of clearance as the "drill" got shorter and the hole got deeper. Rather than use the quill, I fed up with the knee for better control. Ultimately I prevailed, all of the tap removed with minimal damage to the threads.