Drill bits for hard metal

[Otis61]

I've been doing a little work to my saiga .308. One of the things I did was lighten the weight of the hammer for a faster lock time.

The question is what drill bits do you use to get through hardened steel?

[brewskzilla]

er... Out of curiosity, how does that quicken your lock time? I would figure the bolt carrier speed had more to do with that than your hammer weight.

[Otis61]

It does seem like they could have picked a better term, but it's the time it takes from the time the trigger releases to the time the fireing pin hits the primmer. Not the time it take for the action to cycle.

I worked on that thing for a lot of hours. Took 4 drill and about 10 grinding bit, and way more patients than I have. I know the right thing to do would be to anneal it, and work it then re-harden it. Hardening is not something I can do.

[holescreek]

Get yourself a couple of carbide drill bits. I've read that some people have had success with the type used for concrete drilling, I've never tried them on steel. I've always used carbide bits made for steel.

[Otis61]

Thanks holes. I looked around in a specialty catalog, and the selection is mind boggling.

[drine]

What size? I have some cobalt bits that should work and a few carbide that will work.

[Otis61]

What size? I have some cobalt bits that should work and a few carbide that will work.

I started with 5/16. Those only got about 1/2 way through. Then I used the grinding bits. They were cheap. Anyway once I got through I ground the hole a little bigger.

Thing is if this really works, and I get smaller groups, I may want to do this again. Plus I'm sure there will be another Time I want to work hardened steal.

This was just a normal tapco hammer, but it was a lot harder that I thought.

[lakeracer69]

Get yourself a couple of carbide drill bits. I've read that some people have had success with the type used for concrete drilling, I've never tried them on steel. I've always used carbide bits made for steel.

+1 on using carbide tipped concrete bits for some types of hardened steel. Go to a local industrial shop. The ones you buy at the big box stores are absolute garbage. Go slow and use lots of cutting fluid.

[holescreek]

I'm not real experienced in drilling hard steel, in a machine shop it's usually a sign that something went wrong early in the process. But, you need a good way to control your speed. The cobalt bits might work if you keep the rpm's down under 200 and used a few drops of high sulfur pipe thread cutting oil (Rigid brand from home depot) to keep the tip cool. Carbide will be just the opposite with regard to rpm's smaller bits up to 800, larger bits up to 500. Don't let a solid carbide bit grab on you, shrapnel will be everywhere.

[okie shooter]

Most folks wont keep their tools cool, HHS can drill alot, but needs to be kept cool, thus oil. If you forget the oil, almost any tool can lose edge. But carbide cannot be reshaprpened as easy, of cobolt(ant TiNi) loses edge it will lose the coating protecting the edge, thus slow, and keep it lubricated.

[Otis61]

All good tips. Thanks. This is the stuff I wanted to know about.