How do you drill and tap hard steel?b

S

saands

New member
I've drilled and tapped Turk Mausers in the course of projects over the years, but their steel isn't all that hard. I just picked up a 1903a3 receiver (just the receiver boys ... so you don't have to get started with "Leave it as is!" ... it already ISN'T as it was) with the intent of making a nice scoped rifle out of it but these receivers are HARD :eek: How do you guys drill and tap them?

TIA,

Saands
 
Yes, those are hard, in the Rc63 range. There are two ways to drill them. One is to heat the spot to be drilled enough to anneal (soften) the steel at that point. The other is to use a carbide drill and carbide tap.

The first works fine with a pencil flame; you want to get it just red hot but in a small area, not over 1/4" in diameter. Some folks say they use other techniques, but that is all I have ever used and it works fine.

The use of the carbide drill and tap is the best except for two things. One is their extreme brittleness, and the other is the cost. Carbide drills cost something like $15 and taps are around $25, and they are VERY easy to break, so a quick drill and tap job can turn into a costly nightmare.

I will stick to annealing, but there is a combination I have used. I drilled the hole with a carbide drill, then used the torch just in the hole to anneal that point only, so I could use a regular tap. That worked pretty well.

Jim
 
Ditto on the carbide being a total PIA, it is about as brittle as a match stick. I have had to use it for drilling some solid cobalt chrome... not fun. I find I can control drills easily, and not break them, taping is another thing all together and I have broke more carbide taps than I'd like to admit to.

For some hard steels I have had luck drilling with carbide and taping with TiN coated non-carbide taps. This was more by happenstance than design though I belive the item in question was case hardened which may explain why this worked well for me.
 
There used to be a tool,can't remeber a name

A fair size chunk of steel that tapered to a blunt point. You heated that with the point on the spot you wanted to anneal, and it transferred the heat to the reciever. Proper use eliminated any risk of annealling too much of the reciever.

Don't know if anybody sells them, but you could make one fairly easily.
 
Thanks SOOO much for the insights. I was considering finding the carbide taps, but even though I haven't used them, I was afraid of ho brittle they MUST be ... and in small sizes, I wasn't looking forward to the ordeal at ALL.

I like the carbide drill, very local anneal option ... that sounds like a winner that hadn't occured to me.

Thanks again,
Saands
 
www.mcmaster.com

will have most all of yoru carbide tooling needs, not the cheapest but easy to deal with and shipped right to your door.

They have some pretty odd configurations of carbide bits, for some non-gun work I found the spade tip bits worked great as a spoting bit and to get me through the case hardened portion then used a regular HSS bit, I'd obviosly not think that too great of a set of threads would result from a hole drilled all the way with a spade bit.

For an obscure project I ended up haivng to use the smaller carbide in a hand drill, managed to not bust the bit but I was worried.
 
McMaster Carr may have the drill, but they won't have a 6-48 tap. For that you will have to go with a gunsmithing supply house like Brownells.

Clemson
 
McMaster-Carr has long been a favored supplier of mine ... they had the drills for $4 and change, so I ordered a few ... just in case. The 6-48 taps I already have, so I didn't even think to look for them there ... you are probably right, though ... that is an odd thread size ... although I think I got a 0-80 from MC once .

Thanks all ... I think that this will work out just fine with the new knowledge installed!

Saands
 
Drilling hard steel

--In times past, I've lightly center punched my hole pattern and then used a mig welder to anneal the spots to be drilled. There will be the filing and usual re-bluing to consider. Wrap the area to slow the cooling and be patient. Carefully file off the excess weld dot and try drilling. Sometimes this has to be repeated to soften deep enough.
--Brownell's has the bottom taps and screws. Lately, I've been using #8-40 screws as they are a little more rugged.The 6-48 work fine, especially on smaller recievers.
 
Actually McMaster does have them, FYI,

Is just one of my favorite companies. You pay for the service they provide but the same could be said of Brownells which is another one of my favorites.
 
RsqVet, you are correct. In fact, I see two different 6-48 taps in the MC catalog. The cheaper of the two seems to be $17.86.

I hope they have some in a cheaper style! I normally use the least expensive carbon steel taps from Brownells, and I pitch them out after each receiver that I tap. By the five-pack, they are $1.61.

Seriously, I order about once a month from McMaster. They are a very fine company with a lot to offer a gunsmith. I particularly recommend their impact driver for removing stuck Mauser guard screws, #5610A2.

Clemson
 
With care and heat control paste, you can spot anneal a receiver without having to reblue it. And of course, the scope mount will cover the area anyway.

Jim
 
how about cobalt taps. Cobalt is tougher than carbide in that it doesn't chip as easily. Carbide is supposed to be advantageous only ecause of its surface speed, but I have been able to drill through a weld with carbide ( go figure)
 
drill&tap

Sirs:
I know annealing methods but something in my gut rebels at it.
I ream my no. 35 hole with my 31 drill, use a good new tap with a long taper and go slowwwwwwww!
On a Mauser the outer skin will go easilly but the inner core will be hard and zing your drill. I just use plenty of good sulpher lard oil and go slow. You only need about four to six threads!
Sometimes after you get your tap started really good switch to a bottoming tap and that seems to help - I think the secret is plenty of good cutting oil and GO SLOOOOOOWWWWWWW!
Harry B.

P.S. I've only broken two taps in my years - and believe me two are too many!
 
I did the 03-a3 also

Annealing worked like a charm. I used a heat sink around the areas I didn't want to hit and it worked fine. I have since picked the mig welder method as an improved way to anneal but haven't actually been able to do that.

Even with the annealing I go very very slow, just to make sure I get it exactly right.
 
DITTO: I drill with a carbide drill and after all holes are drilled i use the torch, i use a jewlers torch outfit that puts out a very small flame and has worked very well in the past. Get good control over the drilled hole and not warm up the action.
 
I did an M1C replica and had to have griffen and howe do the drilling cuz the dang receiver was so hard it smoked a couple of carbide tips!. They spot anneal, wish I had the stuff to do it!.
 
drill & tap

Sirs:
As Jim correctly points out all you're doing is "softening" the area - annealing isn't done until you reach the critical temp. (around 1300-1500 degrees F). and then covering the part with charcoal till it's cool. Springs are drawn at around 600-700 degrees (F). So, when you're "softening" the action you're probably only drawing the hardness to around 800 degrees (F). (50-55RC)
After thinking it over I don't think the treatment would change the Rockwell (C) much at all.
Douglas checks Mauser actions and for "standard" calibers they want the action ring at 20 PC. For "magnums they want them at 40C!
So, even with a 63C reading to start with I can't see any damage being done.
However, in "softening" a Krag action I heard a little "ting" when I applied heat to the ring - I threw it over the hill! I think that colored my judgement about annealing/softening one area of action rings - the next one I'll try "softening"!
Harry B.
 
Usually only the surface has a relatively high hardness.
If the entire action was that hard it would tend to crack.
Soft actions stretch, hard actions shatter.

Once you get through the hardened layer the core is not nealry as hard to work.

Older tricks include just spinning a piece of drill rod at the desired spot and letting friction heat the metal.
Allow the spot to cool off some and drill with a new HSS bit (use a US made one, not a chinese 'butter bit').
 
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