100# Propane Tank Forge Questions ( I am a newbie)

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brodbeckrt

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Feb 25, 2016
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I have a two 100# propane tanks(used for propane torpedo heater). One has a busted valve and is empty. The other I am going to use for my fuel source. The approximate size is 4ft tall and 12" diameter. I am planning on using the empty one to build a forge. This will be my first forge build and I am new to knife making/forging. I have been researching some of the previous DIY Threads on forges and burners. I have decided to layer the inside with 2" wool then coat with satanite. Then use fire bricks as a floor. I am planning on using the burner from this thread.
I already have the tanks and wool. I also have the tools to do any metal fab I need on this. I need to purchase the satanite, bricks, and burner components (looking to buy locally at building supply stores).

Questions:

Is the burner mentioned above sized properly for a forge this size?

I havent looked into it much, but has anyone robbed some parts off of a torpedo heater to use for a burner?

Will I just be wasting fuel starting out with a forge this size? I had a thought to wall it off with refractory brick to temporarily shrink the chamber.

I dont see a need for a rear door as I dont plan on making anything over 4ft lg. Anyone see any advantages/disadvantages to this?


Does anyone have any recommendations/reservations?

Thanks in advance!
 
If you are planning on using the whole tank, yes, thats a huge waste of fuel for making knives. Id guess most forges are probably in the neighborhood of 18" long and a 4"-6" chamber size. And since I saw that thread you referenced was my burner thread, Ill say Stacy was a big help and the burner works awesome. I probably run it at about 2-3psi which is way better than my old venturi
 
Unless it's going to double as a heat treating chamber for any sword sized projects, then the fuel consumed just to get it glowing would be more trouble than it's worth. However, you could always cut a section that's 2 ft. or shorter, and line the inside with enough layers of kaowool to bring the chamber size down to 6-7" diameter or less - but that's only if you MUST use this other propane tank as a forge body. Discountsteel.com has some of the cheapest prices I've seen for both mild and stainless steel pipe, and my first forge body was a segment of 6.5" schedule 40 diameter pipe found at a local scrapyard, which was willing to part with it for 10 bucks. Do what you believe you need to, though. These are only suggestions.
 
When working in knife dimensions, you can only really effectively work 2 to 3 inches at a time in a single heat before you've lost heat and need to go back in. Heating up any more than that except during heat treatment & normalization is a waste of fuel and space =) The forge I use most when forging knives... is a little tiny single burner NC Tool Co Whisper Baby. It lets me heat just a couple of inches at a time. I have another forge for welding up billets of damascus and another for heat treating.
 
Unless you have considerable experience and make swords, a 48" forge is crazy. There may be less than a dozen in the US used by home forgers. They are also really hard to build and line.

A 24" forge is really big. 16-18" is about right. My suggestion would be to cut the tank ends off at 8-9 inches each and weld them together for a 16-18" forge.

With a 12" diameter, two inch wool will still leave a 7" chamber by the time you are done. That is really big for most work. Adding a fire brick floor and filling in the transition to the sides with satanite will make a "D" shape chamber about 7X5", which should be OK.

The burner you linked to is a good unit. It will run a 16" forge well.
 
I wouldn't chop up a 100lb tank

They can be re-valved and retested cheaper than a new one.


I'd just build the forge using new scrap yard pipe in the dimensions you need.
 
12345678910 said:
I wouldn't chop up a 100lb tank

They can be re-valved and retested cheaper than a new one.


I'd just build the forge using new scrap yard pipe in the dimensions you need.
Click to expand...

YES. I broke a valve on a 100# tank. Just had the propane dealer put a new one on. I would have myself but they did it for $15 and included a new inspection with sticker. I buy enough propane they take care of me... Don't chop up a $150 tank.

You can use a 12 gallon grease/oil drum if you wanted something that large. I use cut up scrap oxygen tanks. I have 2, an 11" and 22". Both will forge weld easily and have about a 6" ID with 1 layer of wool.
 
Thanks all for the great advice. I am just going to build something smaller as directed. I am shopping around for some old tanks or a larger dia piece of pipe at local scrap yards.
 
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