Bob,
On these frizzens I have tried three different heat sources...I have and use a Presto-Lite torch, as you suggest, and it does the heating job very well. After heating to ~1475 F, the frizzen was quenched in Canola oil. It was too hard to file, however, when cleaned up and replaced on the lock, it did not spark. Contrary to the Chambers instructions, I re-heated the frizzen in an electric furnace to 1475 F and kept it there for about 20 minutes. Jim Chambers recommends NOT doing this as the steel will decarburize. To prevent this, I packed the frizzen in bone charcoal the same way I would for a case hardening run. The frizzen was again quenched in the oil and again was not hard enough to spark. On the third attempt, I used a rose bud torch tip on an Oxy-acetylene rig (being careful not to over heat the part) and kept the frizzen a bright red color for a minute or two before quenching in brine. This seemed to work but after a few snaps in the lock, the frizzen stopped sparking again and the surface of the steel was soft enough to beat up the flint badly. Suspecting that the surface may have become decarburized, I ground a few thousands of the steel away and finally got what I thought was an acceptable spark out of it.
I usually do not have this much trouble heat treating a part, but I have had a $#*! of a time with these particular frizzens. I'm sure there is nothing wrong with the part, as it comes from Jim Chambers, as the locks spark beautifully when I get them. I just seem to have trouble getting the frizzen back to its original hardened state after I finish engraving.
By the way, I anneal these by packing the part in bone charcoal and running it up to 1500 F in and electric furnace and then turn the furnace off and let it cool down over night, so I don't think I am decarburizing during the anneal. So, I must be doing something wrong that I am just not seeing...yet. I'm sure if I mess around with this long enough the correct answer will occur to me.
