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Propane Forge: Opening in End?


DC712001

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Building my first propane forge. Already made two 3/4-inch side-arm burners (burner-tubes are 3/4-inch dia. SS-pipe, tested burners and they seem to function well.)

I bought the "body" (a former, portable, Compressed-Air storage-tank, 12-inch Dia x 20-inch long) at Lowes for $35.

I cut one end-cap off the air-tank with a die-grinder/ attached cut-off wheel.

I plan to make the floor from a couple firebrick and line the interior with Kaowool (2 to 3-inch thickness) then coat it with ITC-100 (I have all the materials.)

Still need to finish cutting the two "burner-tube-holder-pipe" holes and line the furnace with the refractories.

Of course, first (before I line the furnace) I need to address the issue of the door/entry and furnace exhaust flow.

Had been considering welding a hinge onto the newly-severed air-tank end-cap on the one end, but realize that the furnace needs to breath.

Also, often a portion of the object being heated needs to extend out the front of the furnace.

So, in practice, should I cut a square, round or arched opening in one end, ... or both ends,... or what???

Of course, "Dragons-breath" is a concern, but so is keeping heat in (efficiency and generating maximum temperatures.)

Therefore, should there be openings in both ends to avoid having the single-opening act like a blow-torch?:confused:

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Your definatly gonna want an opening on both ends.. when you need to heat a longer piece of stock to cut it in the middle or make a twist in the middle, or need to fuller a part or are just working a long piece.. that sort of stuff. I think all of the above shapes would work, mine is square but when its rebuilt I'm probably going to make an arch on both ends with 2 doors.

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I agree with hill.josh. You will want an opening at both ends. I built a gas forge just like the one you are describing. An old compressor tank, two burners and an opening at each end. I did put a door to close off the rear opening. And I made a plug out of some kaowool to help keep the heat in. If I have a long piece to heat, I just open the rear door and pull out the plug. The best of both options. It works well.
Good luck with yours and please post pics as you go. We would love to see your progress.

Mitch

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Derek:

Mitch has it about right. A pass through is a good idea and it doesn't need to be as large as the front opening. Being able closing it up is a good idea for the reasons you express. A lot of guys stack brick in the front to partially close it up.

Frosty

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Thanks much for the replies/advice.

A few more questions:

How much should the Kaowool be compressed after it is placed?

When applying the ITC-100, do you mist/wet down/dampen the Kaowool with water prior to applying the coating?

How and/or how-long do you wait for the ITC-100 coating to dry before firing the furnace?

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I have a gas unit that has a hinged flap on the back, works well but is warped a slight bit from the heat. The Rigidizer or coating often requires firing to cure, when we use the stuf for the hearth of prefabricated fireplaces, it needs a fire to cure it within 24 hours of application, many of these substances are similiar.

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Thanks Mike.

My concern with the Coating application, is that I read something to the effect that if it was not dried properly, you could trap water/moisture in the refractories and this can result in damage to the refractories or even result in minor steam-explosion.

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You should NOT compress the ceramic blanket if you can help it. I only suggested a method that will allow you to slip it into a forge shell without bunching or tearing it.

ITC-100 doesn't or shouldn't go on in a thick enough coat to be in danger of spalling on firing.

Hard refractory liners are a different proposition and must be dried and fired properly to prevent spalling. (not always small steam explosions blowing pieces off)

Air dry completely according to product directions. This will vary according to local conditions, temp humidity, etc. If the humidity is high or temps low you may want to hang a light bulb in the liner to speed drying.

Once completely dry light a small fire in it for a few minutes and allow it to cool completely. Repeat with a slightly larger fire for longer and let cool. Last or final firing varies per product but usually is to a red heat for half to a full hour and cool.

Products will have directions on the package, bag, etc. If not what I just laid out is a conservative cure and firing schedule and should be safe enough for most any product.

Frosty

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I wish I would have been on this forum 2 years ago, man am I picken stuff up that would've been helpfull then! Thanks Frosty!! Hope to met you someday! I just found out I recieved the Alabama forge councils- at large scholarship-
better lucky than good!!

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You're very welcome though most of that info is on the package the refractory comes in.

Living so far from the lower 48 means I don't get to meet a lot of fellow smiths but on those occasion I have it's been a real treat.

If you ever get to this neck of the woods be sure to look me up.

Frosty

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