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Mike Haverstock

Building a forge questions

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A smart guy once told me to use what you have when building from scrap. It’s almost always true. But here’s my situation. I have a 30 gallon compressor tank in great shape. Yes it’s 17” diameter and 28” long to the rounded ends. Yes that’s huge but.....I was at an auction the other day and there was this huge box of what looked like insulation.  At first I really didn’t pay it any attention. It turns out it was 2600 degree ceramic insulation 2” thick, 48” wide and 12.5 feet long. Says 8 pound on it. I guess that’s the density? So what if I put 4” of insulation in then coat with refractory? Would 4” walls be bad? Seems like it would only be better but I figured I’d ask you all. I have enough insulation to probably reline it a couple times over. I can cut a vent hole in either end but still line the ends 6” deep to reduce internal volume more. If my math is right 17 wide -8 for walls and bring the ends into 16” it would be about 1050 cube. So 3 burners? Idk, I know it’s huge but I’d never need a bigger one lol. I know it will use more gas than a smaller one but I’m ok with that for now. If it uses too much I can build a smaller one later. My main question is if there’s anything bad about 4” thick ceramic fiber?

Btw I got that roll of fiber for $1

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Well, considering most standard 20 pound propane tanks are about 14 inches long and 12 inches across, you'd have about double what most people start out with. With that being said, what do you plan on making? If you plan on general knives, then its a bit oversized. But if you're thinking knives and swords, you might like the extra length of it. As for stacking your insulation, you're going to need more than just the insulation to make it work. It will crush down unless you cover it with a thick layer of refractable. In fact I suspect that it will sag over time even with that. I would ask Wayne Coe, I would consider him one of the board experts on this.

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Posted (edited)

I built my second forge from a large gas tank or the section I cut from it. 24 inches was a good length and I cut  a strip down the length of it and used a strap (truck tie down) to squeeze it back together at the new smaller 12 inch  dia.

IMG_20180802_105559.jpgIMG_20180802_110320.jpgIMG_20180810_100140.jpg

 

a pair of plates for the ends were located with bolts and a nut welded to the back of the plate and a larger nut welded to the body for the bolt to slip through and the head against the larger nut allows for the plates to drawn up tight and are removable if the lining ever needs to be changed. I only use this forge for HT the knives that are a bit long for the smaller single burner forge and for hting the stainless blades as I have the temp guages all sorted for this one. Able to hold the temp to    +/- 2 degrees F for the SS blades.

IMG_20180812_131918.jpgIMG_20180816_114520.jpgIMG_20180819_171810.jpgIMG_20180831_091127.jpg

Edited by Garry Keown

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If you build a forge that large not only will it use a lot more fuel, it will cost a lot more to build.  You should be able to pick up an old 20# Propane tank for free,  Four inches is over kill.

Check out the Build a Gas Forge and the Ribbon Burner attachments on the Forge Supplies page at

www.WayneCoeArtistBlacksmith.com.

Let me know if I can help you.

 

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I also recommend that for propane forges, bigger is not always better. Firstly, you will need to figure what kind of burner you are going to use, then understand the cubic inches that it can work in efficiently.  Then realize if your working one piece of steel in something that big, its really over kill.  What you have planned is something piratically industrial in size. And also consider, to run that size for for an hour may cost $5 while something smaller can do the same size work for .50 an hour.

 

Read through Wayne's page, and look at his forge design.  Personally, if I feel like doing it this year, I'm cutting a slit down the side of my little forge to work out of the side of it when I need to. A "c" design allows you to work really big stuff out of a fairly small forge.

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A smart guy once told me to use what you have when building from scrap. It’s almost always true.

But not in this case  Would you use a 1,000 # Propane tank to build a knife forge just because you had it?

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