I'd gotten 2 chisel blanks ready for heat treating so it was time to give my new forge a try. I waited til dark and set everything up in the driveway outside the garage at the request of my wife. I tried to tell her I'd never blown up a house before, but I think she felt better with things outside. :) I was using MAP gas, which burns hotter than propane, with a plumber type torch tip. I got everything set up how I wanted it, turned on the torch and waited. And waited. And waited some more. After 20 minutes, it was pretty clear this wasn't working like it was supposed to. I decided the trouble might be the tip. After a little internet research, I went and picked up a new tip with a swirling flame that claimed to burn much hotter. What a difference. Within 3 to 4 minutes the inside of the forge was glowing red. I put the 1" chisel blank in the forge, turning it a few times, and within a few minutes, the blank was glowing a nice, bright orange color. I checked it with a magnet and it was non-magnetic for about 2 1/2" up from the bevel end. Plenty high enough so I stuck it back in the forge just long enough to get back the heat I'd lost checking it and then quenched it in oil. Cleaned the black of the blank and stuck it in the toaster oven at 375 for an hour and then turned my attention to the 3/4" blank. Same satisfying results. Very quick to get up to temp. I'd read somewhere that some people temper the blades for an hour or so, let them cool, then bring them back up the that 375 temp again for an hour. Not sure if this does any better than tempering once or not, but I did it anyway. When they were done in the oven, you could clearly see the nice straw color that came up 2" to 2 1/2" from the end.
I'm really happy with the way the forge preformed once I switched to the swirling flame tip. Once I get these two chisels cleaned up, sharpened, and handled, I'll try to get a few more blanks knocked out. I believe I have enough O-1 left for a 5/8" and 1/4" or a 1/2" and a 3/8". I feel pretty good about my heat treating set-up now. It's not the prettiest thing, but it does the job.
I think I scared the chisels into submission when I showed them what they were going to get if they didn't act right in the forge. A 500,000 BTU flame thrower, err, weed torch. Lucky for them it didn't come to that. I think my wife was thankful also. :)
2 comments:
I just came across your blog by chance. Your paint can forge looks like a very effective (and cheap) way to experiment with heat treating. Really brilliantly simple. Thanks for sharing, and the the note about using a swirling tip on the torch.
Thanks David. It works really well. Better than I expected it would actually. Heats up really quickly. The ceramic wool isn't cheap, but I still think it was under $50 for the whole thing, not including the torch tip. Not bad for the results you get.
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