Quarterbore.Net Forums

Edmond · #1 11-22-2009, 04:27 PM

Hi Everyone. I am trying to drill 3/4" holes through Rockwell C50 heat-treated chrome alloy. I can't find a drill bit that will last more than a few minutes, even with slow speed and plenty of cutting oil. Any ideas please?

THANKS !

tp555 · #2 11-23-2009, 08:06 AM

You need carbide for c50.Even then it will wear out quick.

JFettig · #3 11-23-2009, 08:29 AM

You'll probably need to hard mill it with high quality coated carbide end mills with lots of coolant in a very rigid machine. I know we do it all the time at work and it works pretty good. I've even watched them mill a pocket with a 1/16" EM .250 deep in 50 rockwell C stainless and hold tenths to the bottom.

Jon

kdiver58 · #4 12-01-2009, 09:33 PM

How many holes and how deep ? 50 Rockwell C is pretty damn hard .. Nothing high speed is going to hold up ..
You are going to need a milling machine and a carbide end mill. Make sure you setup a stop so that you just barely break through. If you plow through fast you will break the corners off of the mill and they don't give 3/4 carbide mills away.
EDM is another option .. good luck