mechelement

1m X 1m Side Blast

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The purple is the pool of Slag forming at the bottom of the fire .

As to sides, straitsisde or slope is a mater of personal tast and angle of repose of the fill. Astarte sided fire bowl won’t last past the first time you fish out the Slag.

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What about the lightweight insulating bricks? Anyone run those? I’m trying to keep the weight down. 

Edited by Mod34
Commercial link removed per TOS

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Is there a rules page here that explains this? Can I post manufacturers names?

Imagine a 3,200*F rated insulated (lightweight) brick I guess. Anyone running this type of brick?

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The overall site rules are here: 

 

The rules about off-site commercial links are here: 

 

It’s okay to mention manufacturers. People do it all the time. Just don’t link to their websites. 

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Just my 2cents worth but why not keep it simple and use dirt or better still clay? it wouldnt blow around and when dry and fired it wouldnt be dug into as easily and its dirt cheap as well Just like the JABOD

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As mentioned in the OP, mobility is an issue: mechelement wants to be able to roll the forge in and out of their garage. 

Another option is what I do in my garage, which is to have the forge just inside the door and add a mobile flue when I want to fire it up. It’s bulky and awkward, but much easier than moving the entire forge. 

046223CB-A3B7-4916-B79F-D90BB0D24991.jpeg

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Their is no need to use hight temp soft brick. Lower temp would be fine, but it lacks mechanical strength. One could fill most of the pan with perlite or vermiculite, one can even use a clay slurry as a binder. This would make you a home made light weight adobe mix to fill most of the pan with having some mechanical strength. Again place hard brick strategically to resist tool damage. Honestly you could get away with many lightweight materials for the bulk of the pan, one could even use wood as long as you have 2-3” of dirt or brick between it and the fire. The same would hold true for rigid rock wool insulation. I would think a cuple of bags of perlight and a bit of clay (builders clay, cheep bentonite cat litter/drysweep or junk clay from a pottery supply if you don’t have a good source under foot) would be the cheapest. Just make up an adobe using the perlight as you would sand (about 2/3) and pack it in the forge leaving about a foot or so around proposed fire bowl. A cuple of bricks set at the bottom of your fire bowl will  provide a mechanical stop to digging the adobe can be molded right around the tuyere thonine might consider sand instead of perlite as an agitate for strength. If you use rubber gloves the addition of ash is said to help prevent clinker from sticking and will stabilize the clay. 

This would be lot cheaper than soft firebrick. As again out side of 2-3” you don’t need expensive refractory materials.

 

 

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That is an excellent suggestion, and one I heartily second. Lightweight, durable, much less expensive than refractory brick, and the perlite is available at most gardening supply houses. Go for it!

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Now we’re cooking with... coke?!

This sounds great. I’m going to call around this morning and try to source perlite. 

Is perlite somewhat similar to lava rock?

I think I’m following you here... The adobe mix should be 1/3 perlite and 2/3 clay and wet down then mixed to bind, then cap the loose perlite in the hearth to within 1” of the top of the hearth with a layer of this mix and slope at the fire bowl, which will slope down to a couple of fire bricks 1” below the bottom of the blast hole in the tuyere.

 Bottom of the fire bowl should be ~8” in diameter or 8”x8” and slope up at around 45*. This will be the adobe cap as well. What about the vertical face of the tuyere at the backside of the fire bowl, make it vertical and nearly flush with the face of the tuyere?

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Found the perlite, but it is horticulture grade. Everything I’ve read, the horticulture grade is much more available and folks use it in their refractories and furnaces anyway. I’m going to go grab around 8-10 cubic feet of this stuff, along with some fire brick and clay cat litter and get this thing tuned up finally. 

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Horticultural grade is fine. 

55 minutes ago, mechelement said:

The adobe mix should be 1/3 perlite and 2/3 clay 

Other way around: 2/3 perlite, 1/3 clay. Just barely enough water to make it hold together: more water = more shrinkage as it dries. 

Use the perlite-clay adobe as the bulk of your fill, not loose perlite. As Charles says, a sand-clay adobe is good for the vertical face around the tuyere, for durability. The rest of your fill should be loose sand and ash, as with a standard (non-mobile) forge. 

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perlite is heated rock expanded to white little puffs much like styrofoam. Vermiculite is expanded mika a volcanic glass. You may have beter luck making a milkshake thick clay slurry and then mixing it into the perlite. Some needing is needed, either in a tarp, heavy plastic or buy foot. The properties of refractory insulation are secondary to price and weight. In a solid fuel forge they are of little benefit. 

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I struck out today as far as perlite. The guy who had the most had some on reserve for another customer. He did tell me he'd get 4 cubic feet of it at a time from a wholesaler in Denver, so he's calling them Monday for pricing and getting back in touch with me.

I'm talking to another guy about pure bubble alumina in bulk and mixing it with the clay cat litter you mentioned. He said that's doable and recommends mixing in 1" long wavy stainless steel "needles" because they'll create a binding matrix within the clay.

I'm sourcing some 3,200°F fire brick and might consider coating that with that bubble alumina coating I mentioned earlier. They recommend a 3/8" thick coating over the fire brick and around the inside of the fire pot.

I didn't really think I had to line the hearth with much of anything beyond a thin layer of dirt or sand. I wish I had been on here planning this out before the forge arrived, or right after it arrived and while modifying it for casters.

JHCC, that's an interesting setup you have there. The chimney ring on the forge I have is at 6'-9" AFF and my garage door is 6'-11.5". With the casters I installed, it rolls like it's on glass. Hitting the joints between the concrete slabs on the driveway is a bit jarring, but other than that, extremely solid.

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26 minutes ago, Charles R. Stevens said:

You may have beter luck making a milkshake thick clay slurry and then mixing it into the perlite.

I defer to Charles's greater experience on this one.

Bubble alumina is waaaay overkill. Ditto the SS needles; you'd have better luck (and more flexibility for less money) with chopped straw.

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Dirt or  is just fine, it has worked for millinia, buy you asked about weight reduction over dirt and i recommended clay and perlite. Traditinaly your type of forge was filled with fly ash and clinker.. each time a new fire was layer on dug down to the right depth and after wetting the ash packed it around a wooden form or tin can to form the fire bowl. Simple and low tech. But a few low tech upgrades are useful. 

Dont get me wrong, I over think things and go for hightech solutions as well, but experience has taught me to simplify and seek lowetech solutions saves one time, money and agrivation. 

So for a lightweight semipermanent durable fill clay and perlight will work just fine, plain red brick will work just fine to provide some mechanical strength and resistance to wear caused buy tools. High heat bricks are not needed as either the heat rises or their will be a lose fill of ash and sand or ash and cat litter between them and the fire. Again the reason I recommend a brick box is because the perlight is a bit soft, instead of brick a sand clay mix can be used, as it has more resistance to wear then the clay and perlite. 

As to dirt. Dirt is a mix of clay, sand and silt in baring praporitions. So when we talk about clay , sand or adobe we are talking about dirt we have taken apart and put back together. 

Anothe reason I like bricks is that side blast dirges lend the,selves to being reconfigured to make effecent special purpose fires, bowls to trenches to tuyer adapters to make heat treating fires to roofing it over to make a furnace when doing a lot of welding etc.if another sketch would help let me know.  

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Another option that is cheap, low-tech, and effective (although requiring a bit more time for setup and takedown) is to use ordinary red brick and — wait for it — move them separately from the forge! Have another cart or a wheelbarrow for storing and moving the bricks and simply set them up each time you roll out the forge. If you have the kind with holes in them, you can hook them out with a poker even while they’re still warm. Shovel the sand into a metal bucket or two, and you’re good to go. 

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Out of curiosity, have you attempted moving the forge with its fill in place? If it moves that smoothly, it might be worth a try. 

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Finally got a return phone call from the nursery. Perlite should be here tomorrow or Monday. It’s 1/4 the cost buying in bulk. Worth the wait!

JHCC, I’ve moved it as full as pictured. 

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