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Nflanders

building propane forge from air tank

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Good evening everyone, I am getting ready to start a forge build this weekend, the body of the forge will be an 11 gallon compressed air tank ( I only chose this over the 5 gallon because I am hoping to work on some wider pieces that might not fit in the narrower body after insulating)

My current plan is

-a rectangular door in the rear with angle iron top and bottom so that I can slide a brick in to block the hole.

-larger rectangular door on the front, also with angle iron so that I can close most of it off to allow higher temps.

-I currently have 2" ceramic wool, 10 x 1/2 cut bricks, and hercules brand furnace cement (home depot's only refractory cement, but it is listed as a "3000 degree cement")

The plan is to start with the wool, paint 2-3 thin (and thinned) coats of the cement, followed by a couple of slightly thicker coats (hoping for 1/2-3/4 inch?), and use a row of 1/2 bricks to line the bottom. Total should be around 540-600 cubic inches.

I have looked at both of these double burner setups ( both from ebay ) as well as a ribbon burner ( I decided against the ribbon so that I am not tied to an outlet for the blower )

Any recommendations, suggestions, things that I am doing completely wrong etc... suggestions are appreciated. 

My other concern is, how necessary is an IR reflective coating? (plistex, metrikote, ITC100) Can it be added later?

 

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Check out the attachment Build a Gas Forge at the Forge Supplies page at www.WayneCoeArtistBlacksmith.  It will tell you how to build a tough, long lasting, efficient forge.  It also addresses the issue of having pieces that are to large to go into the forge. If you want a ribbon burner but don't have access to electricity in your shop do a Google search for Frosty's NARB (Naturally Aspirated Ribbon Burner.

Let me know if I can help you..

Wayne

Edited by Wayne Coe

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Wayne, Is the metrikote ok to apply over the refractory? I've sir that I was reading said to only apply over the ceramic wool, not on bricks or refractory.

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2 hours ago, Nflanders said:

Wayne, Is the metrikote ok to apply over the refractory? I've sir that I was reading said to only apply over the ceramic wool, not on bricks or refractory.

Yes, it is.  I use Mizzou to coat my forge, and then over that is a coat of Hyb-UV.  The IR coat is very thin; really it is just painted on for the most part. 

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That is the way that I use it.  I prefer Kast-0-Lite to other castables.  It is light weight and is an insulator as well as forming a tough, long lasting surface.

Let me know if I can help you.

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Wayne, how much Kast-o-lite, and plistix or metrikote would you recommend? (around 450 square inches of surface area on the inside of the wool) minus whatever thickness the kast o lite takes from the diameter of the inside for the IR coating.

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I would strongly suggest you not use the furnace cement.  It is just that, cement, designed only to join lengths of stovepipe.  Otherwise it will puff up like popcorn and fall off. Kast-o-lite or Satanite is the way to go here, and they are not expensive.  You just have to wait on shipping.

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Depending on the volume needed and shipping costs I will most likely order the kast o lite from wayne's site (along with whatever IR coating I decide on) worse comes to worst I have a decent refractory supply store that I pass every few weeks for work.

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1 hour ago, Nflanders said:

Depending on the volume needed and shipping costs I will most likely order the kast o lite from wayne's site (along with whatever IR coating I decide on) worse comes to worst I have a decent refractory supply store that I pass every few weeks for work.

If you have a ceramics store close by, check with them if you can't order it from Wayne.  They may carry Kast-o-lite, Mizzou or maybe even Satanite.  

I think my 50 lbs bag of Mizzou was like 30 bucks through my local store.  It sets up hard as concrete and is rated to 3000F.  The only bad thing is that it has less thermal conductivity than Kast-o-lite does, which is why Wayne prefers it I am sure.  

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If you are building a forge using a 20# Propane bottle you would need 2' of Inswool for a 1" layer 4 bags of Kast-0-Lite for a 1/2" casting and 1 pint of Plistix or Metrikote.

for a forge built using a Freon bottle you would need 1' of Inswool, 3 bags of Kast-0-Lite and 1 pint of Plistix or Metrikote.

The problem with going to a ceramics store is that you need 2' of Inswool but have to buy 25' you need 20# of Kast-0-Lite but have to buy 55#s and you need 1.5# of Plistix or Metrikote.  I sell it so that you buy only what you need.

Let me know if I can help you. I tell you about amounts needed by giving amounts for forges that I know about, I hope that you can figure out any differences.

Wayne

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fortunately there is a refractory store not too far away that sells their leftovers/ small pieces, so I have enough Inswool and then some... I'm going to see if they can get me some Kast o lite tomorrow, and see if they have an alternative to ITC... if not I will most likely order some plistix or metrikote from you. As far as the volume the tank is a bit bigger than a propane tank, so I figure that I would need at least 20-25 lbs depending on the cost of shipping its probable about the same price for 25-30 lbs shipped or 55 bought locally.

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3 hours ago, Wayne Coe said:

The problem with going to a ceramics store is that you need 2' of Inswool but have to buy 25' you need 20# of Kast-0-Lite but have to buy 55#s and you need 1.5# of Plistix or Metrikote.  I sell it so that you buy only what you need.

 

Thankfully my ceramics store sells exactly what I need.  They cut the length of wool I needed, and have many different sizes of other materials.

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When I go to mount the double burner (the seller says that the outer diameter of the burner flares are 1.5") would it be ok to use 2" pipe? or should I use 1.5" and make it as tight as possible?

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Whichever pipe you choose you'll be stuffing some inswool in the gaps anyway. Take one of the flares with you to make sure it fits in the pipe, it's embarrassing

to have to attach the flare from inside the forge.  Ask me how I know... 

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if it doesnt matter that it is a little oversized I may just do the 2" the burners will take a week or so to get here, and I wanted to get the forge construction started this weekend.

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Alan, Does it matter if I attach the flare from inside of the forge? the guy that I ordered the burners from specified that is how he does it ( the flares and burner holders are both 1.5" )

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Not in the least!  It's just a pain if you made the forge on the small side and you can't see what you're doing in there one-handed. :rolleyes:  Those little 10-32 set screws can be hard to find that way.  This was made from a helium bottle about 10 inches around and I left the doors a bit small as well.  I won't make that mistake again, but it turned out to be a great little forge once I got it put together.

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