Drilling hardened steel

[wdtom]

I will need to drill some 61-62 Rockwell C steel at work. I have ordered a carbide drill bit from J&L rated to drill up to 65. Do you guys have any experience with this? What speed, how much pressure, do I expect a continous chip or powder comming off the bit? Use cutting lube? I have Molly D, recomemded for tough to cut metals such as stainless and titainium. This is not a production deal, for now just one 11/32 hole to take the head of a #12 socket head screw, to locate a part in a machine that is worn where it is supposed to locate. I can use one of the bridgeports in the tool room, which are in good condition, for this operation. Thanks for any advise that will help this to be successfull.

Tom

[banjoallen]

First,use the Bridgeport. Try about 1200 RPM to start.Don't use any lube or coolant.Use an air blast.what you should get is a fine ribbon that breaks easily-and lots of sparks-don't worry about about that.Don't be afraid to push it,just keep the chip clear. You should get a feel for it pretty quick. Good luck! Allen

[Rustybolt]

Get your part centered, then lock down all the axis. You don't want the table jumpin around when you start drilling.

[HWooldridge]

A die drill and slow speed with gobs of coolant will go like 'buddah' - just be careful when you break through the back side as the drill can snag and break. We drill a lot of armor that is around 55 Rc and that's how we do it.

[wdtom]

Thanks guys for the advise, Tom