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I keep reading that people have mixed feelings on using straight clay as a refractory material. I have two questions; other than cracking, what are the major downsides of using clay? The reason I am asking is because I happen to work on a golf course that has incredible quality clay underneath, and free is always my first option, and I am having trouble trying to locally source other materials. Second, I am planning on using an old air tank, approx. 12" di....to save me some thread searching, what would be a good diameter for the inner chamber, and what size T Burner would you all suggest, 1"?

Thanks, Viking.

 

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It appears as though you are combining two things.  Clay is used as a lining for solid fuel forges.  From what you've said your intent is to build a gas forge.  Clay is not a good choice at all for that application. Besides the cracking, it is heavy, not very insulating, and a big heat sink.  The extra cost in propane to run a clay lined forge (even if you were successful) would fairly quickly pay for the cost of suitable materials.  There is a pretty extensive gas forge section on the forum and usually 2 or 3 current conversations happening regarding the construction of gas forges.  Rather than attempt to repeat a significant portion of it here I hope you'll take the time to read through some of what has already been discussed on the forum and you'll get an idea pretty quickly of what makes a good gas forge.

http://www.iforgeiron.com/forum/65-gas-forges/

 

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Thanks for the input! I have been reading through the forum, but I'm still just scratching the surface. The reason I asked is because I read on one post here, that clay was used in a gas forge with success, however there was no mention of it being a heat sink which does makes sense. The weight is not an issue for me (I don't plan on moving it around much). Do you think a combination of clay as the main body, and a good quality refractory material as a cap would be sufficient enough to mitigate some of the heat loss? The cost isn't a make or break factor, but I do like free stuff. Like I said too, I have been having a hell of a time locally sourcing materials, if anyone on here can point me in the right direction that would be great! (I know there are at least a few Albertan's on here)

Also, quick question, how does natural gas work as a replacement for propane? I have a hookup out side for my BBQ. 

Viking

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Insulation is a key element of a propane forge.  You need as much of the heat as possible to stay inside.  Anything that allows heat to escape or to transfer to the outer shell is costing you money.  Obviously you have to have enough of an opening to get stock in and let exhaust out, but beyond that it's money into the open air.  You can look up the R value of clay vs. ceramic fiber blanket and make up your own mind on what makes sense there.  The refractory liners typically used as hot face material inside a gas forge do not provide nearly the insulation of the fiber blanket.  That's why the blankets are only coated internally with a thin layer of the harder materials.  If the blanket could stand up better to the heat, mechanical damage, and if it didn't send lung-damaging particles into the air we probably wouldn't bother lining it with anything - just an IR reflective coating.

Typically natural gas has far too low pressure to be used in a naturally aspirated burner.  It can be used at low pressure, but some kind of forced air will be required.  There are some threads on that topic as well.

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The higher the temperature of the forge gets the better the refractory needs to be. the reverse also holds true; so before you decide how much to shell out for refractory you must decide if if you just want to bang on metal, or you want to forge weld.

Forget clay, sand, etc. BUT, you can increase insulation while saving money if you mix the refractory with Perlite. Just remember the opening lines, becuase halfway measures don't mix well with all out heat.

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Good Morning, BMV

Clay works good as a filler in a Coal/Coke Forge, around the opening, outside of the Tuyere.

Kaowool is available from a local pottery supplier. If you want to boost it, use some refractory material. Talk to one/some of the other Smiths in the Calgary area, They will know who has what. There also are knowledgeable Smiths, North of you, Edmonton.

Neil

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Most of the clay vs. commercial refractories and insulating refractories has been covered but I have one more thing that might help. The interned is FULL of people who say X works but they don't have any idea what they're talking about, what constitutes "will work" as opposed to works properly or well.

Whatever you read not to mention the things you see in a youTube video needs to be checked out. Take it all as a load of BS till you know differently. As you learn more and gain skill your filters will get better. If you have a question ask us, we'll help keep you from painting yourself into a corner.

Frosty The Lucky.

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Thanks Frosty! I'm learning very fast just how much BS is out there. I've decided on the Creel design Air tank forge with some comfort mods(work rest, hinged door, etc.).

I also had a completely dumb ass moment when I finally realized that my father is a heating and plumbing contractor and can get me anything I need. 

Viking

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You're welcome, it's my pleasure. Don't be too surprised if the mods XXX out the "buttock" part of the Dumb AX in your post. It's a family site and they try to filter everything so your 8 yr old daughter can read and look at the pictures without asking Mom and Dad to explain words and terms. Don't sweat it we all slip, just don't be surprised. I call that a "head slapping moment" or I'd slip more often. It's also part of the charmingly pithy character I assume here. ;)

I'm not familiar with the "Creel" forge plans, have a link?

I haven't made a cylindrical forge in a long time other than helping someone else. They have one really handy virtue as early forges, their volume is easy to adjust. Most folk, myself included, build WAY too large a forge early on and a cylindrical forge can be smallened simply by putting a wider kiln shelf in it. Adjustable volume is as easy as making a movable back wall.

Frosty The Lucky.

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Take a look around, there are much better designed forges. That one is too large and the openings are very much too large unless a person is going to be heating crazy large pieces.

It's a good Side Arm burner how to but I personally HATE how the final fuel line is connected to the burners, it's all a fragile trip hazard. Murphy's law rules so keep your bets hedged. Just look at the last pic on the site, all that rigid pipe is sticking straight out of the side of the forge a long way then has the hose hanging from it. A puppy running past could break one of the 1/8" nipples off one of both burners and seeing as that's where your shut off valves are they'd be spraying propane at or next to a HOT forge. shutting the gas off at the tank valve takes a few seconds and if a broken fitting falls aimed at the tank?

Personally I'd shorten the 1/8" scd 80 nipples just long enough to do final adjustments and hang the 90* elbows pointed at the ground. Then run either propane rated hose or 1/4" copper tubing to the manifold and 1/4 turn ball valves. Then the hose to the tank and regulator. A set up like that allows you to anchor the fuel lines at the burners and anybody tripping over the hose to the tank isn't going to break fittings or hoses. It also places the quick shut off valves away from the fire.

Make sense?

Frosty The Lucky.

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I like the simplicity of the side arm burner, but I am still considering other designs. I have access to a drill press and vice, so I have also been strongly considering your T Burner design. I am right there with you on the fuel connections, I've already started looking at another way to hook it all up (I read in an earlier post of yours discussing the benefits of copper tubing over rubber, makes perfect sense to me). I also don't like how precarious it looks, I know he said to add a stabilizing arm but I see a huge potential for the whole thing to roll.

My tank is considerably smaller, I didn't have the exact measurements the other day so I guessed it at 18" deep, but it was 14", which will make my final volume (before the kiln shelf) at 395 cu.in. As for the size of the opening, I was tossing around the idea of welding a piece of angle iron to the front as a work rest, but also so I can use some fire bricks to adjust the size of the opening. I was thinking of hinging the front end as well, to make it easier to repair/replace the refractory. 

Viking

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Copper vs. rubber depends on where it is in relation to the heat of the forge in my "Build it safe FIRST" play book. With the burners nearly horizontal as built in that design rubber is well away from the HOT stuff and doesn't give me any heartburn at all.

The burners on my shop forge on the other hand stand vertical on top of the lid. When you shut it down chimney effect gets the burner on that section HOT is seconds, rubber wouldn't last long on mine. Add to chimney effect is what happens with the burners not in use. The lid of my shop raises and lowers so I can arrange the partition dividers as necessary for whatever. The partitions don't seal perfectly so there is always some blowbye into unused sections and those burners become exhaust ports and chimneys.

There just isn't a safe way to supply gas to MY forge's burners with rubber. I feed the manifold with a rubber hose from the reg, gauge and tank but it's copper from the manifold to the burners and I don't care how hot they get. If copper lines melt I have bigger problems than a little exhaust eh?

Keep your first forge as simple as possible. I THINK (and my thinking is wrong often enough I'm used to it) hinges sound better than they are. If you need to replace the flame contact liner it'll be ready to fall out already so just make a little hook pick and peal it out. Keeping the new liner in place is as simple as cutting it an inch or so too wide to fit, roll it up and squeeze it in it'll spring back and stay right there.

Putting a strap hinge or hinging the ends I don't get the advantage. They just add another interface to have to get sealed. I think it's something that sounds good to someone who hasn't built a forge before and is trying to deal with problems they imagine might exist.

Making an angle iron shelf at the opening is a good thing in more than one way. If you make it wide enough a brick will lay flat on it it makes a fine helper to support long stock in the fire and you can stand split brick on edge to control the opening. Stack bricks and pieces in whatever way makes the opening you want for THAT job. I have a pile of broken pieces of light fire brick on top of my shop forge and a couple boxes in a corner. for just that reason.

What I did for the brick helper shelf was to mount it on sq tubing that telescopes into sockets under the forge and holds the split brick level with the forge floor. This lets me slide the brick out from the forge to support even  longer stock. That wasn't enough so I added a telescoping helper that's just a 1" angle iron cross bar on sq. tubing. Combined the brick helper shelf and helper lets me support stock up to 3' fro the forge mouth. Better still, the sq. tubing on the helper bar is the perfect place to hang tongs. It's a twofer! :)

Have you seen pics of my shop forge? I've posted them a bunch but pics have a limited lifespan on IFI's new platform.

Frosty The Lucky.

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Thanks for the help Frosty!

I have seen a couple pictures of your forge once, but I haven't been able to track down the thread I saw it in.

Its funny you mention a telescoping shelf, I had the exact same idea, with the only exception being, I didn't think to use sq. tubing, that would definitely make the welding easier.

I have a bunch of 1/4" copper tubing lying around so I might as well use it for my connections. 

My pops is checking his suppliers for a ceramic blanket and I just need to put together a parts list for him for the burners. So hopefully soon I should have some major progress done (mind you, my girlfriend just moved in this weekend, so I have a feeling my shop time will be quite limited). I'll post some pics as I go. 

Viking

 

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I post a pic or two every once in a while to illustrate how I do the propane lines in the hot zone. I'd be posting pics of my new portable if it worked better, maybe when I get it debugged. The portable illustrates a couple ways to prevent the trip hazard the propane lines represent but I want it working properly before I use it as an example. Maybe it could be an example of "Looks good but isn't."

I'm looking forward to seeing you up and running.

Frosty The Lucky,

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