- Joined
- Feb 24, 2017
- Messages
- 56
I am trying to drill through 5 inches of 4140 steel. I am doing so on my Atlas horizontal mill at the lowest RPM.
I started a pilot hole of 9/64 using a cobalt drill. after going to the max length I changed over to a long HSS 9/64 bit.
I fed slowly and cleaned chips out regularly and then snap the bit broke off deep inside the project. Good thing it was just a practice piece.
larger bits feed very well as long as there is a pilot, trouble seems to be getting a pilot all the way through.
I ordered a long cobalt bit and hope to be successful with that but could use any suggestions.
thanks
I started a pilot hole of 9/64 using a cobalt drill. after going to the max length I changed over to a long HSS 9/64 bit.
I fed slowly and cleaned chips out regularly and then snap the bit broke off deep inside the project. Good thing it was just a practice piece.
larger bits feed very well as long as there is a pilot, trouble seems to be getting a pilot all the way through.
I ordered a long cobalt bit and hope to be successful with that but could use any suggestions.
thanks