Cobalt, Not Carbide

3/32" Pin Diameter, Pin Punch
Similar to the one we used

Jack is refurbishing an old gun. Step one is to take it apart. He has stripped it down to the receiver. There are two press-fit pins that go through the receiver. One comes out easily but the other one, which is the pivot for the trigger, won't budge. I think he is being timid with the hammer, so I carefully line up the punch with the pin, give it a good whack with an 20oz ball pein hammer and the punch bends. Looks like we are going to have to drill it out.

20oz ball pein hammer

Clamp the receiver to the milling machine and chuck up a drill bit that is slightly smaller than the pin (which is like one-tenth of an inch in diameter), carefully line up the drill bit with the pin and start drilling. We make good progress for about a tenth of an inch. We can tell because we see chips coming off of the dill bit. But then it stops. No more chips, and when we press on the drill we can see the bit is bowing out to the side. Hmmph. Maybe the drill is dull. We try another bit but it doesn't produce any results either. Hmmph. We must have run into some hardened steel. You would think that if the end of the pin was soft enough to drill, the whole pin would be the same, but this gun is 100 years old, and maybe the pin is supposed to be hardened, but the treatment didn't affect the ends.

IRWIN VISE-GRIP Original Curved Jaw Locking Pliers with Wire Cutter, 10", 502L3

Jack orders some carbide drill bits from Amazon and we manage to drill a quarter inch deep on one side and almost as far on the other side before the carbide bits quit as well. It isn't enough to free the trigger, and in any case our hole is close enough to concentric that we haven't impacted the walls of the hole. (We used a magnifying glass to adjust the position of the drill.) But maybe we have done enough that a punch will now work, and so it does. We manage to move the pin, but the business end of the punch is not long enough to drive the pin all the way out. Some grinding on the shoulder of the punch elongates the business end and allows us to push the pin a little farther, far enough that we are able to grab it with Vise Grips and wrest it from the hole.

DEWALT DWA1240 Pilot Point Industrial Cobalt Drill Bit Set (14 Piece)

I just now realized that the Amazon page calls the bits cobalt, not carbide. Carbide drill bits are available, but are considerably more expensive.

No work photos becasue my Lumix camera bit the dust. I have another one I can use, but I need to get a case for it before I start dragging it around.