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I Forge Iron

New gas forge coming along....slowly but surely


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gas forge project ....its about 24" x 16" diam...... made from a long propane tank...the other half with the feet (it was a large verticle tank) has become the beefiest trash can in my shop :)

filled it with water prior to cutting, to make sure nothing would explode......

its kinda big, but i plan to shrink the interior space as needed with insulation. the front door will be made with insulation bricks so i can easily adapt the opening size. the back of the tank is closed.....i might open it up later so i can feed stuff through though

will get 3 Reil style burners fed from 2 propane tanks......i'll have an idle loop and valves cuz i dont plan to run all 3 burners all the time....i'll have to see how it does.....i'm hoping i have enough heat to use one burner most of the time

so there it is!

anyone got any good suggestions and sources for the floor material.....right now i'm just going to lay an insulation brick on the bottom and hope for the best.

also, how do i attach the koawool to the sides of the enclosure?



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Use 1", 8oz Kaowool cut it about an inch longer than necessary to fill the tube when rolled up with the ends butted. Then cut a second piece to fit inside that one for 2" total insulation.

Instead of using an insulating fire brick for the floor, use split 3,000f hard brick(s). They're WAY more durable, especially if you get flux on them.

Another option is kiln shelving. It works well but is a lot more expensive. It's best feature is it's a lot thinner and heats up faster.

Whichever you use lay it on top of the Kaowool so it's insulated as well. You may need to float it on only one layer of Kaowool but that's still WAY better than no insulation.


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In order to get that to a 350 cubic inch per burner ratio, you will need to reduce the diameter to about 7.5 inches for a 24 inch long cylinder. Frosty is right on the money about the insulation and the hard brick floor. The insulation will stay in place if you follow his advice, without the use of any retainers (one of mine has survived 4 years...
), and the hard brick floors are durable. Use 1" insulation as it is more flexible and easy to form.
Unless you are heat treating large blades or texturing long pickets, do you really need a 24" long forge? You can always make a "plug" to reduce the chambers length when you don't need all that space, that and the Idle Circuit will really save a ton on gas!

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Unless you are heat treating large blades or texturing long pickets, do you really need a 24" long forge? You can always make a "plug" to reduce the chambers length when you don't need all that space, that and the Idle Circuit will really save a ton on gas!

thats actually part of my plan....the back side of that tank has a threaded hole where the gas tanks valve used to be.....I'm going to use firebrick to create a movable back wall......i'll have a handle connected to the movable wall, to create a plunger i can change on the fly, so i don't have to turn off the heat in order to change the volume of the forge. i havent figured out all the details yet, but i figure i could secure the fire brick from the back with a metal structure and have a handle come out through the valve hole......i'm not sure if that makes any sense...but i got it in my head :)

I'm waiting to sell a Lathe i have before i proceed....need the money :)

anyone need a nice lathe!?!?!? :)

thanks for the replies guys
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Forge looking good there, if this is your 1st gasser Ive got a couple of pointers from my first, if youve made a few you may think different.....

Im an engineer, and like neat, clean engineering solutions to things, my main frustration building the thing (there are details in ' show me your gas forge, and the mods are in my 'damascus materials & info thread) is how imprecise the forge body is,

no matter how hard I tried it never came out 'neat', plunger moveable walls sounds good on paper, but when that suckers upto 1300 / 1400 degs it all goes out the window, and you find yourself prodding firebricks with a pair of tongs to reduce the volume.
Lining, with a bit of coating / sag / etc youll be lucky to get + / - 1/4" ! :)

you might be aswell to spend a bit of time reading up on burner entry angles and 'gas swirl' - On advice (from Mike Blue, a well respected knife maker who knows a bit about gassers) I put my burner at 3'oclock poistion - I thought this would just hot spot the wall but it really works.

You could consider rotating your entire forge 90 degrees? - Ive read up a lot about forges (including Absorbing Micheal Porters entire book!) and it still seems to be a slightly 'dark art' to get all the variables right, anyhow, this is mine, goes superhot at low gas pressure through .040" mig tip

your mileage may vary !


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