Welding and Metalworking - What steel bit to use to cut through Hardened metal

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cubix
08-04-08, 05:25 PM
I am trying to drill some extra holes(approx 4-5mm dia) in a lock strike plate which is approx 5mm thick. The striking plate is for a secutiy lock (abloy EL412) so I presume its made from some kind of hardened steel. I have tried my normal hss bits but not even making a dent, any ideas

Cheers

marksr
08-05-08, 04:15 AM
Welcome to the forums!

I've always liked cobalt bits for hard to drill metals.
hrjrkr
08-05-08, 04:41 AM
Also try spraying the bit while drilling with some type of lubricant like oil. That will make the bit last longer.

cubix
08-05-08, 05:58 AM
Thanks Marksr, looks like this board has quite alot info for the grey matter;) . Will checkout your suggestion regarding cobalt bits and thanks for the tip regarding oil HrjrKr. I would normally put a little putty reservoir around the hole to be drilled with some ordinary 3in1 oil but I think I will have to get something a little stronger for this job

Cheers Lads:thumbup:
Speedwrench
08-05-08, 06:08 AM
the masonry bits that have carbide cutters will work for drilling very hard steel. they work best with a drill press and lots of lubricant. do not try to hammer drill on steel. slow speed and steady pressure. or a drill bit that is ground neerly flat with only about a 5 degree slant to the cutting edge will work for very hard steel lots of lubricant and no more than 600 rpm.

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