What do you think of my idea?

[bbydlik]

I have seen lots of forges built out of old propane tanks. I want to build one out of an old compressor body. It is 29 1/2 inches from seam to seam and has 2 1-1/4 ports 5-1/2 inches back from the seams. (see picture). I am using this with the intention of putting in two independentally controlled burners so I can do longer projects. I want to mount it on wheels so I can move it from a heavey duty pop up type structure to my patio (6 feet). The rest of my shop will remain under the tent, I want to mount the propane tank under the forge. Oh I have never used, built or seen in person a propane forge. Here are my questions.

1. 
   Given the xtra area will it work with one burner?
2. 
   Is 5 1/2 inches back from the front and back to short of a space?
3. 
   Any safety issues I am overlooking?
   

For the record I have years of experience with domestic natural gas piping and boiler repair. I hold a NJ High Pressure boiler Operators licensee. I know about pressure and venturis.

[macbruce]

First and foremost you do NOT want your forge THAT close to your fuel source!!! If TSHTF you need to be able to turn off the fuel away from the fire. .....I believe one burner per 355 cubic inches of space is nominal and that tank will be way over that.....Do you need one that big?

[bbydlik]

Good Idea about keeping the tank away from the forge. Thats not a problem at all. I dont know if I need one that big. Are there issues that I should take into consideration?

[ThomasPowers]

Often when I see long forges proposed they are intended for swordmaking and so I will answer WRT that: In general you never want to heat more metal than you can work at one time---waste of energy, scale loses and for blades decarburization and grain growth as well.

So for a sword forge the hot area should be around 6" long. Only time you need it longer is for heat treating and that is a rare occurrence compared to forging.

As an analogy: a forge much bigger than you need for most of your work is like using a dump truck for your daily driver because twice a year you need to get a load of gravel. It can be done but you soon waste more in gas than actually getting a car for daily driving.

In general smithing there are times you need a long heat. However I think it is better to build your first forge to deal with the normal tasks and think about the odd ones when you get to them.

Make sure your forge has a back door so you can pass long bars through and you can get a heat in the middle of a long bar.

(When I needed a long forge to box fold some 3/8" plate I dug a trench forge in my back yard. Took about an hour to build including making the tuyere. Used it to fold the plate and filled it in.)

[bbydlik]

Ok sounds good. It seems that the longer forge will be more trouble then its worth. I will make it out of the bbq propane tank and save the compressor tank for another project.

[bbydlik]

Thanks for the advise.

[knots]

That tank looks more suited for a nice quench tank than a forge. Click on "Gallery" and search "Quench Tank". That should take you to 3 images of a quench tank that I built out of a 40 LB propane tank. The tank top is fabricated from one of the domed ends hinged so that the dome flips into and seals the tank in case of a flash flame.

I agree with Thomas as I always put a opening in the back of the forge so that longer work pieces con pass through . Normally I make the back so that an insulating brick or two will tightly close the opening left for poking stuff through.

I have a larger propane forge that I built for making bulky items and hardly ever use because the forge is just to fuel hungry . Consequently most of the time it sits around unused occupying valuable space.