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Background 

I've built a break drum forge in my back yard. Currently I'm using metallurgical grade coal I get from a local supplier, I enjoy using coal a lot, but winter is coming, and I can't use it close to the house (girlfriend hates the smell/dust/smoke, sure the neighbors don't appreciate either).  I have 2 old standard sized LP tanks, and I wish to make a forge out of one.  I've already taken the proper precautions to make the tanks safe to work with.

My Questions:  

I want to use a combination of insulating wool blanket and refractory cement, preferably a castable.  How thick should the blanket layer be? How thick should the refractory layer be?  Can I even use a castable for this, or do I need to use something that packs? My plan is to modify

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Check this video out for building a propane forge. I built mine from it. Love it.

http://www.youtube.com/watch?v=VxzdqcPzXj8

Here is a pic of mine.

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I put 2 inches of kaowool in, coated it with Plistix, put a firebrick in the bottom which brought the floor up the same level as the opening I cut. I have a smaller opening at the back end for longer stock. I have a handle on top you can see in the photo. Two more just like it for "legs" to keep it from rolling. It roars.

And check out Wayne Coe's site for some of the supplies. Not sure of everything he carries but I got my Plistix 900 from him. Fast.

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Check this video out for building a propane forge. I built mine from it. Love it.

http://www.youtube.com/watch?v=VxzdqcPzXj8

Here is a pic of mine.

'?do=embed' frameborder='0' data-embedContent>>

I put 2 inches of kaowool in, coated it with Plistix, put a firebrick in the bottom which brought the floor up the same level as the opening I cut. I have a smaller opening at the back end for longer stock. I have a handle on top you can see in the photo. Two more just like it for "legs" to keep it from rolling. It roars.

And check out Wayne Coe's site for some of the supplies. Not sure of everything he carries but I got my Plistix 900 from him. Fast.

Oh I saw this on the front page the other day. Do you just use firebrick for the floor?  I wanted to add a refractory layer to the design to give it more durability, I hear that just the wool and a refractory coating wears out quickly.  I'm also worried about the dust it gives off if it breaks down, hear its pretty bad for you
 

 

Read the tutorial on my Forge Supplies page on my web-site.  Contact me if you need more help.

Thank you very much!  I think I understand the tutorial though pictures would be great if you have them.  Is the refractory mortar layer very thick? I didn't really see anything about how thick to apply it, maybe I missed that part.

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Actually, I mis spoke.  The youtube video is for the burner. The forge itself was kind of what I had seen with paint cans, and other cylinders that people used for forges. I am sure I am not the first one to use a propane can though. It is heavy steal and very durable. I worried a bit about the durability of the lighter cans. I have a tendency to over-build stuff anyway. The burner works really well. It takes a bit of tweaking to find the right settings on the needle valve and I had to adjust the choke on the mount tube. He had his choked completely but mine would not burn that way. I have to have it about half choked. The front opening is just slightly larger than the fire brick. The real trick is getting the kaowool in. It isn't nearly as flexible as it appears and it can crush. I don't know if crushing is bad but it probably does not help. I used one inch and put in two layers. Then circular pieces for the front and rear. Yes, the fibers will break down and you don't want to breath them.  I painted a good coat of Plistix inside, another neat trick. Took a couple days to dry. I would start the forge up just to get a little heat in there to speed up the drying. I think I am going to put a second coat in also. Wayne has a good price on the Plistix. I have a full fire brick in the bottom. You will want to put the brick in while the Plistix is still wet to shape the bottom and then you can pull it back out. I also put a thinner slab of fire brick on the wall opposite the burner to help bounce the heat. I dont know how hot it gets but I am at forging temps while my buddy still has caustic smoke billowing out of his coal. I like coal but propane is so much easier and portable. I pick my forge up in hand and propane tank in the other and I am on my way.

 

Cutting into a propane cylinder is a bit nerve wracking though. I had mine vented and the I shot a hole in the bottom from a good distance away just in case. It was a lead projectile so it shouldn't make a spark but who wants to take that chance. Then with my air compressor I would jet air inside the hole to work out any remaining gases and still let it sit for a couple weeks. When you cut the opening I think you could go larger  and not loose much heat. That would also make it a little easier with larger or odd shaped pieces that I find difficult. I have toyed with the idea of continuing the opening around to the side about half way on my next one. Then I could block the side opening with a fire brick but pull it out if i had the larger pieces to work on. The hole in the back is much smaller and is used to push longer stock through. I will get a couple pics of the inside cold and put them up. Hope this helps.

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Cutting into a propane cylinder is a bit nerve wracking though

Yeah I was worried about that, but I thick it'll be okay, filled it up with water and let it sit in the sun until about half the water evaporated. I've had it laying around with the valve removed for a while so I think it should be okay. Probably fill it up and dump it out a few more times before I cut it.

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Was actually going to cut off the top a circular saw and a cutoff wheel, like in that video I linked -- still have to build something to hold the tank in place. Cutting it across the circumference is tricky because the tank likes to spin and the saw likes to kick. I probably will leave some water in the tank when I cut, probably help cut down the number of airborne metal flakes any way, that stuff got in my nose when I cut a helium tank up for my coal forge. Probably going to wear a mask this time.

Just found out today my neighbor has a 300# Peter Wright in his garage, with a stand. Barely  been used. Said his old man bought it in the 60s and used it around the shop occasionally.  When he said I could borrow it I about died, thing is beautiful and my hammer bounces like a super ball off the face.  Step up from the RR Track I'm using now for sure.

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Rinsing propane tanks isn't helped by letting it soak any length of time, the mercaptan oil is the oderant added so you aren't surprised by a leak. In extremely unlikely cases the mercaptan oil itself can be a fire, explosion hazard as it soaks into the pores of the steel and evaporates when heated. However it is easily removed by adding a little chlorine bleach to the rinse water, just fill the tank, let it sit for a few minutes and empty it.

 

For "pipe" forges I prefer stainless steel stove pipe, unless you're going to be forging really heavy stock it's plenty strong, it'll support 60-75 lbs of axel easily. That's what I tested mine with so it's not just anecdotal opinion, I've actually done the experiment. Another plus for SS is it's a lot ore reflective of IR so more heat stays IN the forge. The plus for stove pipe is the off the shelf accessories, Wall hangers make perfect legs and bushings make nice ends with openings. If you use one 4" smaller than the shell you have just the right amount to contain 2" of Kaowool.

 

If you're using a ceramic blanket for a liner you most definitely want to use a kiln wash to protect it from handling and welding fluxes. It encapsulates the fibers as well so you're not subjecting yourself to the same level of inhalation hazard.

 

As to kiln washes ITC-100 is one of the best, it is Kaolin clay and zirconium flour. the clay is a high alumina clay so it is far more resistant to caustic fluxs and yes borax at welding temperature is VERY caustic and will dissolve silicates very quickly. Subject Kaowool to molten borax and it will dissolve like cotton candy under hot water. Fire brick only holds up a little better. Okay, that's it about kaolin clay and borax, in fact you can use kaolin slip as a kiln wash and it will make the blanket and fire brick much more robust. On to zirconium, this is really amazing stuff, just less hard than diamond, it has a vitrification temperature in the 3,000C range, as I recall, nearly 7,000f and that's just to fire it like the ceramic it is.

 

In ITC-100 the kaolin clay is a matrix to hold the zirconium because a propane forges, even an oxy propane torch isn't hot enough to fire zirconium. Oxy acetylene maybe but I don't know.

 

A member here has come up with a recipe for home brew kaolin/zirconium kiln wash, Phil K. by most of his name. He's had good results using a mix of 70% zirconium silicate to 30% kaolin. I'm using a close approximation in my forge and it's working very well. A close approximation the kaolin I have is already a slip so I can't do accurate measurements, No way I'm going to the trouble of doing a specific gravity.

 

Dave Hammer has a recipe and method he's developed and I'm afraid we disagree about our differences. I have nothing bad to say about Dave, he makes some pretty darned excellent contributions to forge making, I really like his version of ejector type naturally aspirated burners, as effective and a whole LOT easier to make than my version.

 

Our difference of opinion is in recipe I like kaolin clay as the matrix material, that and kaolin and zirconium silicate are non-toxic, there is NO reportable quantity, if you spilled a 20 yard dump truck load on the highway, no hazardous material warning would be issued, it would be a road hazard, not a health hazard. It is also very resistant to caustic erosion. Dave uses Kaolin silicate in a binder of sodium silicate and coloidal silicate. this is a standard kiln wash recipe used by glass blowers to stabilize and act as IR reflector in glory holes. It's very effective and frankly perfect for a glory hole and most ceramic kilns. Unfortunately both sodium silicate and coloidal silicate are haz mats, you really need to use PPE, once set and fired it's less hazard than a grass window. And molten borax is caustic, silicates dissolve easily in caustics so it is far more susceptible to forge welding fluxes.

 

And that's the sum total of Dave and my difference of opinion, he does good work and I respect him a lot.

 

Regardless of what you wash your forge with if you do, wet the ceramic blanket and especially fire brick first or they'll draw the moisture out of the wash so fast it will flake off rather than stick. Masons call this "buttering" and it's been a must since bricks were mortared together. I just put the brick in a bucket of water for a few seconds before washing them. Let them dry till a finger touch leaves a little white powder o your finger and light it for a few minutes. Let it cool and light it up again for a little longer, let it cool and sit for a few hours or even over night to allow all the moisture to escape. Then fire it up for at least an hour at high yellow heat, the kaolin will continue to fire for quite a few sessions, it's a cone 12 clay so it'll take a long time to turn to proper porcelain in one of our forges.

 

Frosty The Lucky.

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Dang, wish I knew about buttering before. Oh well, One more time.

 

GraphicH

Nice find on the PW. Move it over yourself. Then when he wants it back he might change his mind and give you a good deal. 

I think there are hundreds/thousands of good anvils out there holding things down. The owners just don't realize the demand for

them so they sit or go to scrap. Shame.

 

A jigsaw with a good blade will cut it well also. Dont know that I would leave any water in it if I was cutting with electric tools though.

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Rinsing propane tanks isn't helped by letting it soak any length of time, the mercaptan oil is the oderant added so you aren't surprised by a leak. In extremely unlikely cases the mercaptan oil itself can be a fire, explosion hazard as it soaks into the pores of the steel and evaporates when heated. However it is easily removed by adding a little chlorine bleach to the rinse water, just fill the tank, let it sit for a few minutes and empty it.

That's a really great tip!

Seems most people are suggesting I just go with the wool and a wash, with a firebrick base.  I suppose since this is my first gas forge I should really try to keep it as simple as possible and just do that. If I were going to do the zirconium silicate + kaolin  is there a place online I could buy these things?  I've had trouble finding high temperature materials/supplies in my area, not really a market for it here I guess.  Ebay appears to be my friend.  For the wash, what kind of consistency do you mix to, like how many parts water to the 70/30 mix of the zirconium & kaolin?  I  see in ceramics a slip is about the consistency of heavy cream, so I guess just make up the 70/30 mix and then eye-ball it to a good consistency?  Great tip on the Zirconium+Kaolin mix that will save me a ton of money over ITC100 (which frankly, I didn't want to buy at that price). Why is ITC100 so expensive?

Sorry for all the questions, I really am in the dark about all this, all the advice is greatly appreciated.

Gunny,
I might try the jigsaw like you say, the circular saw is a little unwieldy for me. 

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  • 2 months later...

my name is chris. it's been a couple years since i've been on this forum. i've had all of my shop put away is storage for a while since i've lived in an apartment. now i'm back in a house and i've gotten everything set up again. yeah!!! :lol: anyway, i am doing some maintenance on my propaine bottle forge. i'm having a problem getting it up to welding temp. i was having this problem before i moved so i just use coal. it didn't stop me from welding. now i can't use coal cus of were my place is located. well, lastnight i relined the kaowool with new refactory clay because all the old clay flaked all off over time. i think that is why i was having this problem. i think the heat was escaping due to not enough insulation as i was able to weld with no problems when i firstr built it. this time, i pulled out a thin layer of the kaowool and lined the majority of the insulation with the clay. i let it set at room temp overnight @ 22 hours, then i went out and fired it up at about 3psi with air and let it run with the piece of kaowool replaced (permanently) for about 30 minutes. then i let it cool and ran it again for about 15 more minutes. the clay has hardend and it doesn't steem anymore. 

 

my question is, should i fire it a few more times or should that be good to start working again. by the way i live in colorado and it's pretty **** cold out. but not so much in my shop as the forge has heated it up.

 

thanks, chris

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Guest 569ec1a27ea4c874823ed052defdc5bc

Chris,

There are so many factors to your question. You might get better results and answers had you started  new thread rather than hijacking this one. You are asking about repairing a forge liner. OP is about building from scratch. That being said,what kind of clay are you using? Is it actual refractory clay? River clay? Porcelain clay??? As a general answer, I would say if the clay is hard, and it didn't crack on the first two firings, you are probably good to go. Depending on what kind of clay it is, this may vary your results. My guess is it isn't fully fired but it can only get better. However, you won't know until you get it hotter

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