Vertical drum forge

Bailey Knives

Bailey Knives

Knifemaker / Craftsman / Service Provider
Joined
Oct 18, 2004
Messages
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Sorry if I misled you with the title to think I had made one of these, I am actually looking for information on it. My little heat treat forge is making it difficult to evenly heat larger blades, I can do it but it requires a bit of a dance and I would like to forgo that if possible. I was looking on Don Fogg's site and saw some 55 gallon drum forges, but I dont know if I need something that big. I would plan on heat treating all my knives in it, large and small, and thought I could just reduce the size of it a bit, maybe using part of a large propane tank. I have an old 100# tank that I was thinking I could cut down (I understand all the dangers with cutting into a propane tank, and will take proper precautions, trust me.) What information I was really looking for is if cutting a 100# tank down would be counterproductive for what I am trying to do, which is to keep an even heat on blades up to 2 feet long, and down to 3" long. Does anyone have a WIP on making one of these?

Thanks in advance.
 
Thanks, I have actually seen that one at one point. Do you think it would work if I reduce the size of it to about 1/2 the dimensions? I basically just want to see if I am wasting my time. Maybe I should do a WIP on the forge as I am building it. We'll see how things work out.
 
I've seen a couple of the Don Fogg HT forges. The first time I saw one, I was very impressed at how technically elegant the whole design was. I gather that particular one was actually built by Don Fogg himself. I got a strong impression that the amount of insulation (1") and the size of the drum (a standard 205litres/55 USgal/45 ImpGal) were pretty close to optimum. I do remember that one of my first thoughts was "someone who doesn't fully understand this is going to try to improve it by insulating it better or by making it smaller, and they're gonna make a pig's ear of it".

I'm fairly sure that uneven heating from any hotspot near the burner is minimized by the workpiece being further away from it (inverse square law), making a large volume, or at least diameter, desirable.

Within limits, shorter might be OK; perhaps 24" long? Likewise a bit longer is probably OK too.

I get the feeling that making it vertical won't help it work well. I get the impression that the horizontal arrangement, with the blade inserted through the exhaust port, means that, if there is a vertical temperature gradient, it will put the length of the blade at the same level and therefore the same temperature. I'd expect less even heating if vertical.

That first one was a "tweak the burner until it holds the required temperature" arrangement. The second one I saw was a PID controlled unit. Both worked equally well, as far as I could tell. The PID version was obviously a more time-consuming build and needed electrical power for the controller and solenoid valve. It used 2 off-the-shelf propane torches, a small one as a pilot burner and a larger one as the main burner. Once set up though, there was no need to tinker getting the burner set correctly each time it was used.

For a more compact unit, I'd go electric every time: I've built 5 electric HT ovens so far, 4 of them for blades up to 18" long and one for blades up to 42" long. The long one has yet to be used in anger, but the shorter ones seem to work OK. Here in the UK, we don't enjoy the availability of reasonably-priced knifemaking equipment that seems to be the norm in the US. Import costs are high so self-build is by far the cheaper option.
 
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