- Joined
- Dec 22, 2015
- Messages
- 561
I'm in the process of making a bushing using 4340 steel. The OD is 1.570", ID is 1.250" and it is 2.050" long. After turning the outside to diameter I started to center drill the second end and the bit broke, leaving the whole tip, below the taper in the work piece. I put the work in the rotary table, thinking I could mill around the broken bit deep enough that I could drill from the opposite end and then bore through to the milling cut byt eh broken center drill bit. Bad idea. I got everything set up in the rotary table and using a 1/4" 4 flute mill end I started taking a 0.025" DOC and made it around one time and noticed it was getting harder to cut. Dropped another 0.020" and started the second pass and the mill end was done. I tried again with a 2 flute and a 0.010" DOC and it didn't make it 1/4 of the way around before it was too dull to continue. These were both new mill ends.
I thought about just drilling through from the good end until I hit the center drill but figure that would lead to a new set of problems when the drill bit made contact with the center drill.
I'm at a loss as to how to work around this broken center drill. Help please.
I thought about just drilling through from the good end until I hit the center drill but figure that would lead to a new set of problems when the drill bit made contact with the center drill.
I'm at a loss as to how to work around this broken center drill. Help please.