Need help tempering pin punch

[wolfshieldrx]

My son collects watches. He has a punch for removing the pins that hold the band links together. The punch has replaceable pins. The pins that came with the punch are brittle and break easily. I tried replacing them with some mild steel ones I made but they bend too easily. I have been trying to make up some from round spring stock. As supplied, it seems too hard and breaks easily...so far my attempts to draw back the temper has been unsuccesful. I either get them too hard (breaks) or too soft (bends). Any suggestions for tempering these small pins? They are only about 1/32 inch in diameter and less than 1 inch long. I seem to remember someone tempering small tools by heating to red/orange and plunging in either a bar of soap(!) or a chunk of beeswax. I don't remember which.

thanks in advance...bart

[Glenn]

Start off by selecting the steel suitable for the job at hand. Then use the correct temper process and temperature for that known steel.

Not on something that small, but I recall tempering small parts in a container, pipe, etc being heated to the proper temperature in the fire. Gives a more even and controlled heat.

[son_of_bluegrass]

If we know what steel you are using we can give better answers.

For small size, I'd start with "music wire" from a hobby store. That is round and available in small sizes already. I make my own stitching points for leather sewing from such stock. To heat treat, I heat either in the forge if I'm already doing something there or use a plumber's propane torch. When using a torch I heat in a darkened shop looking for the descalesence then quench in a container of water. I temper usually in a household oven. For your application I'd guess 475 to 525 degrees F for an hour would be a good place to start. I would also heat treat each piece 2 or 3 times longer than needed and cut it to length after the heat treat.

ron

[wolfshieldrx]

Thanks guys. After doing a little research, I found that the "spring stock" I am using is 1070. Will try the oven temper tonight. Thanks again...bart

[Ken Nelson]

There may be a different problem that is being overlooked here. 1/32" is quite thin, and has little lateral strength. Hardening and tempering to a higher hardness may help, but if you are not driving the punch directly forward, then you will get flexing and bending in the punch. One thing to check would be the punch holder, how straight does it hold the punch, is there a angle near the top of the barrel, and is the hammering surface directly in line with the punch? Any of these could impart lateral forces. If your son is not coming down directly with the hammer blows, you can get the same problem. The ends of the punch are important too. In a case like this they need to be exactly perpendicular to the shaft, or the punch will flex/bend opposite the higher edge. One other thing that may help would be to make the punch as short as possible to get the job done.

While heat treat is important, and getting a good even hardness will help tremendously, I think there may be more than one dimension to the problem.

Good luck

[Larry H]

you might consider making a sleeve to hold the pin and push it through with a second pin, or try a pin in the annealed state,......the carbon content alone may be strong enough to do the job and it wont be brittle