How do you drill carbon steel lock parts??

[Rolf]

I'm building two Swedish officer pistol locks with brass plates and small siler parts. I bought some cheap HHS drills from Tracy Tools UK. Each drill was completely worn out after barely drilling one hole in the annealed carbon steel parts (tumbler, frizzen and sear). I used a high quality cutting oil.

Have buy more 33 and 9/64" drills. Any recommendations that don't cost an arm and a leg?
Any advice drilling carbon steel siler parts?

Best regards
Rolf

[Dphariss]

Unfortunately tooling has really gone up in price the last 3 years or so.
Use medium speed, oil and a positive feed rate. Make SURE the tool is cutting well failing to do this allows heat to build in the part and then harden in front of the cutter. Some alloys are more prone to this than others.

Dan

[E.vonAschwege]

How fast is your drill speed set to?  When drilling HC steel I use the slow/medium speed on my drill press and use a slow and steady pressure.  As it was explained to me once (and perhaps a machinist can correct me if I'm recalling this wrong), the slow speed keeps the friction and heat down as the tip makes cuts.  The steady pressure is important - if you push too hard you can chip or dull the bit and create too much friction, and if you don't push hard enough the drill will spin and not cut, also dulling the bit and potentially creating a hard spot in the part you're drilling.  Good luck Rolf,
-Eric

[keweenaw]

If the work is at all hard you'll get much better service from cobalt drills but I suspect the problem is more in what you are drilling.  Tumblers, frizzens and sears are frequently cast from 1095 or another high carbon steel.  While they don't come hardened, they shouldn't be considered annealed and may have enough hardness in them to ruin about any bit you use.  I think you'll find if you anneal the parts with a very slow cool either in a furnace, shut off after coming to temp (1500 F) and let to cool overnight without opening the furnace, or by heating with a torch to bright red and then cooled overnight in wood ashes or vermiculite and follow the suggestions of others they'll drill just fine with high speed bits. 

Tom

[Acer Saccharum]

Rolf, I think your best plan is to anneal as Tom S says, then drill again. Slow turning, with oil and steady pressure.

[Jim Kibler]

I suspect your parts weren't very well annealed to begin with.

[LRB]

  Siler internals are 01 steel. Your best anneal  is a  spheroidize anneal. Heat to 1350°, and soak for an hour. If you have a ramp controlled oven, let it cool at 50° per hour to under 900°, and then it is done. This causes the carbon to separate from the iron matrix, and form balls, allowing for easy cutting. You can try just heating to 1350° and air cooling a few times. Sometimes this alone will get the steel soft enough to work with. A long slow cool will cause the carbon in 01, or any hypereutectic steel, to layer, and often is still hard on tooling. I have had good luck on thin sections with the simple heat to 1350° and air cool 3 or 4 times.

[E.vonAschwege]

Food for thought for those saying these parts need annealing:  I've worked on a bunch of as-cast Siler parts and never had any trouble drilling them except when I screw up and break a bit.  I suppose there's no reason why you wouldn't go ahead and anneal these anyway just to make life easier, but if they are also as-cast, why would these be harder than regular? 
-Eric

[Acer Saccharum]

A fast drill speed will harden the hole, burn the drill in two nano-seconds. Nothing short of a carbide drill will get thru without annealing the parts.

If you then try to tap the hardened hole, you risk breaking the tap.

[LRB]

  01, and other steels containing chromium have a tendency to air harden when cooling from a red heat. I would think that the parts are cast with no further treatment, so will have varying degees of air hardening as they cool. I would also suspect they have a large grain structure from the casting process which is probably not corrected either, making them a tad more brittle than they should be, and possibly one reason for the occasional  unexplained break.

[Hungry Horse]

I've never had a problem with anything I got from Siler/Chambers. But, I alway use a carbide bit, I always run my drill as slow as it will go, I always use tapping fluid, and I always drill a pilot hole. Skip a process, or use poor quality drills, and taps, and you're asking for trouble.

                            Hungry Horse

[Dphariss]

01 is really bad for hardening with slow feed speeds or dull tools. I have had it round over a brand new HSS endmill even when it comes full annealed. I use carbide if I have much machining to do. Drills OK with a positive feed rate.

Dan

[Rolf]

Thank you for your replies. Could only find carbid drills in metric sizes in Norway, but I was able to order some cobolt drills in the rigth size. The guy in the store said they should be able to do the job.

My drillpress has these settings; 600, 900, 1250, 1750 and 2600. What speed do you recommend?

Best regards
Rolf

[Acer Saccharum]

600.

with cutting oil.

[LRB]

 I would agree with Acer on the speed, and that a cobalt bit should work. I drill a lot of 01, and use cobalt most often. I'm not sure I agree with using cutting oil though. In my experience, just saying, in my experience, cutting oil used with cobalt bits just causes an oily drill table, and does not seem to help the cobalt bit as it would a HS bit. I used to use oil with the cobalt, but got tired of having to clean up afterwards, so stopped using it. Bits lasted, at worst, just as long, and seemed to maybe last longer.

[Bob Roller]

Rolf,
600rpm or slower. I have your other E mail and will send you another
to your personal mail soon.

Bob Roller