Any ideas on building a gas forge from an old wood stove?

[John G]

I'm thinking of picking up an old wood burning stove (the fireplace kind, not the cooking kind) and refitting it to become a propane forge. Does anyone have any experience doing this, and if so, what should I look for? There are several good sized stoves on Craigslist for around $100 that could work... but I don't know if I would have some sort of hidden problem.

Also, is it possible to inject oxygen into the propane to increase BTU's or fuel efficiency? Just wondering...

Thanks in advance for any input.

[pkrankow]

What size material are you planning to work on? The cavity in a cheap wood stove is very large, even after insulation you will have a huge internal volume. which will require a lot of fuel to heat.

People have experimented with injecting oxygen with mixed results. I would not as steel melting temperatures can be achieved with propane in air. If you really need this kind of volume then a "recuperative forge" design may be what you are looking for.

Phil

[MattBower]

Phil's question is apt. A propane forge based on a wood stove would be huge, and would require a large investment in fuel and in materials. Are you certain you need it?

I'd stay away from O2. It's expensive, unnecessary, complicates things, adds a bit of a danger factor, and won't necessarily be good for your steel or your refractory.

[Rich Hale]

There has been a lot of questions on here about building a gasser. If youi would like to read through this part of the forum and look qt the qs and A's you will pick up a lot of information in a short time about building one. Lots of folks have spent a lot of time typing in thoughts on this. Hope that will help.

[John G]

Thanks Rich, Matt, and Phil, for your input. Hadn't really thought about the extra size factor, and how much fuel will be needed to heat that up... Plus, I guess I really should read the forum, as I am realizing more and more how little I know about this, and I really subscribe to the theory that I should try to learn from others' mistakes before I have to learn from my own. And thanks for the info on O2, Matt. I was touring the Bullseye Glass factory in Portland last week and they inject O2 from a LOX system into their natural gas, and it saves them a lot of money, so I had a thought it might do the same for me, but on such a small scale, and using it for steel rather than glass, I could see where I would not only not get any benefit, it may actually be detrimental. (BTW-- if anyone gets a chance, they have free public tours for individuals or groups at Bullseye Glass, just call and set it up. They are easily the nicest business people I have ever met, and how they do things there is really fascinating. I could watch those guys dropping 10-lb. dollops of molten glass into the rolling machines for hours-- but then, perhaps I am easily amused...)

Well, I'd better get reading! Thanks again, you guys.

[ThomasPowers]

Most propane forges tend towards oxidizing anyway; just adding O2 would make things worse and there is already too much O2 anyway.

I'm betting that the glassworks are not using any atmosphere and so avoid all that useless Nitrogen that has to be heated up but gives no benefit. If they mix pure O2 and NG correctly almost all the heat goes into heating their work.

Glass is such a fuel hog it probably makes sense. For forging if you need that much heat I'd go with a fuel oil forge and skip the O2.

[MattBower]

I was surprised about the pure O2 in glass furnaces, so I did some reading. It looks like oxy-fuel reduces NOx emissions (which is a cost savings for industry) and can improve efficiency in a number of ways (e.g., you can use smaller furnaces, or pack more material into existing furnaces and still achieve the target temp, and you can eliminate regenerators and recuperators). On the down side, O2 is expensive, more difficult to handle, and requires higher quality refractories. Unfortunately, most of those benefits aren't obviously applicable to a small-time smith, and most of the disadvantages probably are..