jbg230
Member
I set out to make a set of mini tools with carbide cutters since my larger carbide roughing tool worked out so well. I bought a 1/2" square bar and some mini cutters. Shaping the bar for the round cutter was easy. It's the tapping of the thread that has me depressed. (pardon the pun)
The screw for the cutter calls for a 4-40 tap. I drilled the hole with a 3/32" bit. No problem on the drill press. I used the cheap tap from my tap and die set and it broke about half way in the hole. The bar must be some sort of hardened steel. I purchased an Irwin HSS tap from ACE Hardware and the same thing happened. I am only using a "Super" household oil, but I'm doing the 1/4 - 1/2 clockwise and counter clockwise turns as I go.
S I cut off the bar end, re-shaped, and drilled again for the 3rd time. I then tried my handheld drill with the broken tap bit, forward and reverse, forward and reverse. Broke the tap down to the nub.
So I tried to get educated. It'd be nice, but $150 or more for a drill press tapping head isn't the answer.
I guess I need a cobalt 2 flute plug style tap. They're about $15.00. There are so many versions though, I'm kind of lost.
Can anyone recommend the correct 4-40 tap for stainless or hardened steel? What brand? Does Nitride play a role?
If it's recommended that I getting a tapping oil instead of my household oil, I'll get it.
Thanks for any help.
Jake
The screw for the cutter calls for a 4-40 tap. I drilled the hole with a 3/32" bit. No problem on the drill press. I used the cheap tap from my tap and die set and it broke about half way in the hole. The bar must be some sort of hardened steel. I purchased an Irwin HSS tap from ACE Hardware and the same thing happened. I am only using a "Super" household oil, but I'm doing the 1/4 - 1/2 clockwise and counter clockwise turns as I go.
S I cut off the bar end, re-shaped, and drilled again for the 3rd time. I then tried my handheld drill with the broken tap bit, forward and reverse, forward and reverse. Broke the tap down to the nub.
So I tried to get educated. It'd be nice, but $150 or more for a drill press tapping head isn't the answer.
I guess I need a cobalt 2 flute plug style tap. They're about $15.00. There are so many versions though, I'm kind of lost.
Can anyone recommend the correct 4-40 tap for stainless or hardened steel? What brand? Does Nitride play a role?
If it's recommended that I getting a tapping oil instead of my household oil, I'll get it.
Thanks for any help.
Jake