BeaverDamForge

My 2c. :

Using the heater in the heat gun will help, but it's the expensive way to go. Maybe use it at first to help get up to temp.

Straw in the mud (clay) will help prevent cracking, but don't use too much. Perlite is much better than ash for refractory. You can add so much ash the clay won't bond before you get to the effectiveness of 50% perlite.

Good Luck!

I had found an archived thread of yours about a gasifier you tried. Are there any pics posted anywhere? I'm using an updraft gasifier with chips of Virginia Pine (grows like crazy here, pretty useless for anything else).

Elmer Roush told me he makes his charcoal from the scraps of a cabinetmaking business.

Almost all the steel I use is scrap.

Good Luck!

I picked one up last weekend in the "iron in the hat". Actually, I won it for a friend who sent money with me. But it might be forever before he sets up a shop, so I set it up in mine "until then"...

The threads are a bit worn in this one, but the price was right. It's the same size, no markings, different bracket and spring, but they may have been replaced.

Good Luck!

As to the ash dump, see the attached photo. KISS, Keep It Simple So it works.

I use a (metal) bucket of water with my brake drum forge, it's the slack tub too...

Some straw in the mud helps keep it from cracking, but don't use too much.

Good Luck!

If you can heat it, shouldn't you be able to tell the difference by the scale (or lack of) formed?

Good Luck!

I had a box bellows at my wood (charcoal) forge, but went to an electric blower for consistency with my gasifier.

Good Luck!

I wonder if Tyvek would be a good replacement for the leather. Strong, flexible, not likely to be eaten by rodents.

Good Luck!

I just read your "Free Coal" thread, that might be part of the problem.

Good Luck!

Once you get the fire established there shouldn't be much smoke. How are you putting new coal on the fire? A chimney may dilute the smoke some, but mainly gets it away from your face.

Good Luck!

I've got maybe $500 in mine... more in the roof than the bucket of tools... it's all I need for now.

Good Luck!

8)The perfect size is what fits your work.

Thanks! I looked a bit when I built my wood gasifier forge but couldn't find anything on shape. I'm trying to get it a bit hotter now, hence the question. I may rebuild the oven with a flat roof instead of arched to reduce volume. Is the volume the real factor or is it surface area of insulation?

Good Luck!

I used a box bellows for my wood (charcoal) forge, and initially set it up to use with my right hand (I'm right handed). But then I realized I was doing everything with my right arm and changed it when I moved my forge. The coal forge I've used is set up to crank with your left hand. The blower would be in the middle of the floor otherwise, but I think it was laid out that way on purpose. Sometimes I need my good hand to position the iron just so in the fire, that's probably inexperience.

I also used a rivet forge with a pump lever on the left side.

Good Luck!

More than you ever wanted to know.

Mr. Reil's Home Page

I got all my parts here.

Burner Flares & Gas Forge Parts

Lots of info on burners, and some on insulation, but couldn't find anything on shell shape... it's a big site, maybe I missed it. Where should I be looking?

Good Luck!

What are the pros and cons of round VS box shaped gassers? It seems like most websites advocate round shells, but most I've actually seen are boxes. I've yet to see one in use, coal seems to be preferred at demos.

Good Luck!

If it's difficult, we do it immediately.
If it's impossible, it takes a little longer.
Miracles by appointment, only!!!!!

That reminds me of "I have done so much with so little for so long that I can now do anything with nothing."

Good Luck!

"It's not your daddy's barbecue"

Good Luck!

Here's a diagram I drew up, I don't think any of the dimensions are critical. I used a 2' piece of 6" stove pipe but cut the crinkled section off. I drew the internal parts in red, but the top cap actually fits flush with the top of the pipe. I have a hole saw that's about 2 5/8, so I cut a hole in the cap that size and made tabs around the edge to open it up to 3". I made the lower baffle in a similar manner, also leaving tabs around the edge. They help support and seal the parts. I also used the tabbing to offset the bottom of the inner pipe a bit (for more clearance for the air valve) since the hole I drilled to let air through was 1 1/2" (I had a hole saw that size). The grate is a 3" drain grate from Lowes, I left a 1/4" gap instead of pushing it all the way into the tube. It's secured with a couple stainless screws. The air inlet tube is a piece of 2 1/2" exhaust pipe flared to match the hole and held in place with high-temp (exhaust gasket) silicone.

I didn't draw the air valve, it's just a cone that slides into the hole in the baffle to control air to the grate. I have it hooked to a choke cable that's working well after getting the hanger bent just right. I also didn't draw the holes in the inner tube, a dozen 5/16 holes just under the cap.

Take a look at the pix in post #50, and let me know if anything isn't clear. I figure I have about $35 in it, not including the failed plywood stand(or scrounged items; exhaust pipe, cart, blower, mud, wire, screws).

I've found that I can close the blower inlet down almost to 1/8" and the "dragon's breath" is a lot better (tamer) but I have to open the lower air valve more.

Good Luck!

Thanks, simmonds - I was starting to think I was talking to myself!

CWB, pellets could be used with a different grate and might need different upper air holes. In the Phillipines they make gasifier stoves that operate on rice husks with a 3 watt blower (computer fan). Mine uses a squirrel cage fan out of an old microwave and it's a lot more than I need. I put shelled corn (maybe a tablespoon at a time, along with several wood chunks) in mine after the fire is established. Corn oil makes a nice fire!

Good Luck!

Okay, I installed the gasifier in the cart, holding it in place with wires. I insulated the bottom with mud/perlite/straw from the bottom of the other setup. I broke up the oven and reused it also, but I think I would have done better to get more perlite and use that. The ash/mud doesn't seem to insulate or hold together as well as perlite/mud. I had to add a layer of perlite/mud/straw to the top, the outside was getting pretty hot.

I found that after getting it started with the blower, it will maintain a gas flame with natural draft*. Inside the oven, with a full fuel load, the flame detaches and fills the oven for a few minutes. The iron is getting to a medium-to-light orange, at least as hot as I ever got with my wood/charcoal forge, so I'm satisfied for now. It uses less wood, and it's more convenient to start and heat up, but the dragon's breath is wicked!

Good Luck!

*edit: The natural draft flame isn't intense enough to forge with, but will keep it fairly hot if you have to stop and talk to someone. I don't leave the area with a fire going, of course.

Yeah, the deep fire wasn't happening in the brake drum - it needs some additional side area, maybe a hubcap...

Corn works great in a gasifier (along with wood chips)!

Good Luck!

I tried using corn in a brake drum forge, all I got was a lot of flame and a sticky mess. It did burn away but the heart of the fire was not getting metal visibly hot (red). I was probably using too much air, I had to turn it way down when I switched to coal - maybe that was the problem.

Good Luck!

I built a brake drum forge a couple weeks ago. Instead of making an ash dump, I ran the tuyere (exhaust pipe) down into a bucket of water. It seals the bottom, puts out any embers, and serves as slack tub.

Good Luck!

OK, Monday morning - a fresh week - and I decided to go for the metal cart. Well, after an examination of the cracks revealed a LOT of fixing was needed. Making the oven opening smaller might prove dicey too, best to redo it. Anyway, I tore the mud/straw out of the bottom and removed the gasifier. I was planning on inverting the outer tube to deliver air to the hot spot or lower, so more heat would be carried with the combustion air.

The 3" flue pipe was a mess! Above the throat I made from exhaust tubing it was discolored and wrinkled, which doesn't show up too well in the pics but it's pronounced. There were pieces of scale falling out from between the throat and pipe, so I knew the throat wasn't holding up either. Good thing I got in there and looked.

I went to Lowes and a couple specialized places, one had a piece of 3" stainless flue pipe for $31. I checked with a muffler shop and got a piece of used 3" stainless pipe for free. That's my kind of price.

The pics -

The 1/4" holes I drilled around the top of the inner tube for combustion air.

Discolored and wrinkled tube.

The old grate installation - you can see the bottom of the throat tube; the other end was flared to meet the 3" pipe.

The scale was .010 - .015" thick.

The air valve cone with coat hanger through it and looped at both ends to hold it.

Freebie cart with hole cut for gasifier. Turning the shell over pointed the air inlet away from the ash cleanout, works better here.

Freebie 3" stainless exhaust pipe.

Good Luck!

Edit: Without the 2 1/2" throat tube the area should increase 44% so the velocity will be a bit lower this time too.

Well, I finally got my gasifier working but not quite forging heat yet. A couple more fixes and I think it will be good. The opening is too big and some cracks in the mud need patching. You can see them in the last pic, they set the box on fire... Earlier in the week I got the oven done and fired it up but the inside of the box started to char so I shut it down, and after it cooled I drilled some holes and added mud/perlite/straw for insulation. You can see some steam coming out where the plywood is slotted together in the first pic. There is also steam coming off the oven in the pic where I'm holding the iron. Hopefully it will get hotter when it's all dry.

I guess the lesson here is don't use a wooden box unless you leave lots of room for insulation - these things get HOT! I would have abandoned it but the air valve arrangement needs to pivot at just the right place to work smoothly. If I can figure a good way to do it I may move the gasifier to a metal cart a friend gave me.

I think my superficial velocity is a bit on the high side - there's never any ash in the bottom to clean out...

Good Luck!

Last thursday I made a brake drum forge to take to a hammer-in. I lined it with red mud and ash mixture, packed in with straw which controlled the cracking pretty well. I put some more mud in the small cracks but they still opened a bit when it dried.

It performed pretty well (4 hrs), there is one soft spot that needs more clay/ash and a glassy spot where the (stainless drain) grate warped and let air come up the side. I was wondering why I was having trouble controlling the fire in that area...

Good Luck!