Azhobbychick

Gas Forge Build by first timer

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Hello from AZ everyone. I started with a standard barbecue propane tank, cut the collars off and made duel opening measuring 5”x5” which I will adding doors too later I have cut off one end to get the lining and refractory right and so far I have just applied the htc 100 to the inswool. I will by updating the thread as I make progress. I have ordered a burner from devil forge as my husband has requested that I not use my homemade frosty burner in my first attempt :D I think he’s nervous... 

The next step is lining, buttering and painting the top piece. 

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Good start Hobbychick. Don't waste ITC 100 that way AGAIN! :o ITC 100 is a kiln wash and is properly applied last of all to the liner. It's not the best product even if it weren't crazy expensive but it helps. ITC 100 is a release agent to prevent ceramics and gazes from sticking to kiln furniture and similar uses in commercial furnaces. It's not really good in a propane forge, it remains chalky rather than firing hard. It rubs off after a while as it's designed to.

Matrikote or Plistex are kiln washes formulated to fire hard as: mechanical and chemical armor and as IR reradiators. They just don't contain zirconium silicate.

The order of forge lining from shell in goes like this: Two layers of 1" 8lb., 2,600 f. ceramic blanket refractory. Cut it a little longer than necessary to wrap around the inside so you have to compress it a little to fit. The compression will help hold it in place.

Butter the blanket and spritz with a rigidizer, currently fumed silica powder mixed with just enough water it will spray out of a cheap'O stray bottle. A couple drops of food coloring in the mix will tell you visually how evenly you've coated it.

Repeat for both layers of wool. and heat cure it with a hand held butane soldering torch or your burner just to red is fine. Correct me please if I have that part wrong Mike.

The next step is plastering or casting the hard refractory inner liner in place. Currently Kastolite 30 li is  consensus better refractory. Wayne Coe is a member here and sells small quantities for reasonable $. He'll steer you straight on quantities when you fill him in on particulars. The number he'll need are the total number of sq/in of the inside surface including the doors. OR you can calculate the total cubic inches and save him a couple gray hairs. Yes?

Whatever you use for the hard liner you want a 3,000 f. water setting high alumina castable refractory.

Do the ends, doors, etc. at the same time eh?

You can plaster Kastolite if you mix it wet enough to move easily, it's filled with aggregate so it's gritty stuff. The recommended water content is for maximum strength and heat rating in industrial settings, we can get away with wetter and easier without hurting the quality of our forge walls. 

If you use Kastolite follow the cure procedure for portland cement concrete. It's NOT the same stuff but it behaves and cures with the same procedures. 

Once it's cured it's time to fire cure it. Bring it to not quite red heat and allow it to cool, then bring it to bright red for half an hour or so allow to cool and it's ready to go to work.

Frosty The Lucky.

 

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Remember that you want the Kast-0-lite to frame the exhaust opening like a lip to keep the temperature of the steel forge shell from overheating.

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Good catch Mike I forgot that part! :o

Frosty The Lucky.

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We got to make sure she protects the shell, or we can't get her to go for the baffle wall :)

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Hello, AZ.

Have you decided on what to do for legs on your forge? Do you know where to position the burner port? Best see to those items before you go much further with the insides!

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Thanks guys I will fix that mistake! That’s the main reason I posted it. I have already marked out the entrance for the burner and was planning on doing a 45 degree angle on the halfway point to swirl the flame. From what I have been reading that is a good way to avoid hotspots? 

I am currently building a frame out of angle iron with crescents cut into it that match the curve of the tank. I was planning on putting that frame contraption on top of a rolling steel cart with wheel locks. The intake tube/mounting tube for the burning is planned to be a 1” black steel pipe with for tapped holes for bolts to hold it in place.

Thanks guys I will fix that mistake! That’s the main reason I posted it. I have already marked out the entrance for the burner and was planning on doing a 45 degree angle on the halfway point to swirl the flame. From what I have been reading that is a good way to avoid hotspots? 

I am currently building a frame out of angle iron with crescents cut into it that match the curve of the tank. I was planning on putting that frame contraption on top of a rolling steel cart with wheel locks. The intake tube/mounting tube for the burning is planned to be a 1” black steel pipe with for tapped holes for bolts to hold it in place.

Thanks again for the advice! And see @Frosty, I told I’d screw up soon :)

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16 hours ago, Azhobbychick said:

Thanks guys I will fix that mistake! That’s the main reason I posted it. I have already marked out the entrance for the burner and was planning on doing a 45 degree angle on the halfway point to swirl the flame. From what I have been reading that is a good way to avoid hot spots?  

This is the second most common mistake; right after wanting an oversize forge. It takes very little flame angle to promote swirl in a tunnel forge., like yours. All that you will accomplish with such a great angle is to have your flame impinge on wall area, instead of on the floor. Whatever you use for a hot-face on the forge floor is going to be much tougher than what you will employ on the wall.

If you position your burner to target the near side of the floor area, its flame will still swirl around the forge just fine, but it won't be overheating the wall, or  your work, which would also be bad, because of scale buildup and carbon loss from the steel. So you'll want to mount the burner after you place your floor, but before you rigidize and seal the wall.

Consider mounting your burner port centered at 2"  away from top dead center. Cut out a hole a little under the outside diameter of the pipe, and then  power sand it into an oval shape with a cheap rotary tool (you can pick them up used from eBay for twenty bucks). Rotary tool accessories are dirt cheap too. It takes very little oval shape to permit the burner port, and thus the burner it holds to be aimed perfectly at the floor.

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Mike posted before I did so I deleted my thoughts on burner angle, no need repeating things. Have you double checked to see your burner will fit through the 1" pipe you're using for the mount? You want a little slack around it so you can fine tune the burner's angle. 

You'll want a couple few inches of clear air between the forge and the cart top or the cart will warp. A sheet of concrete backer board makes an excellent heat shield under forges and if you're careful you can lay hot work on it so long as it doesn't stay hot too long. Normalizing hammer head on the backer board would probably overheat the cart top and warp it. 

If you're going to make entertaining mistakes you're going to have to up your game. Seriously you haven't done or said anything I can have fun with. <sigh>

Frosty The Lucky.

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36 minutes ago, Frosty said:

You want a little slack around it so you can fine tune the burner's angle. 

It's also handy to be able to slide the complete burner, including its flame retention nozzle in and out through the burner port. Placing the nozzle on the burner by working on it through the forge's exhaust opening is a real drag!

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For the record the one inch pipe is one hundred percent not gonna work! It needs to be closer to 2 inches it looks like. I will re-evaluate size once the burner gets here.

I have not cut a burner hole yet so no problems there. I can move it by washing off the marker. 

Beforw I make another mess up like using $30 worth kiln wash for nothing, what types of things do you recommend for the floor? It sounds like my cast floor may not be best? 

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Depends on the material. I'm told Kastolite 30 (which I used for my own forge) is very resistant to flux and reasonably resistant to the inevitable knocks and bumps of forging. Some people here use sections of kiln shelf, but that's outside my own experience and expertise.

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Mike's funnin with you, you can slide the burner far enough into the forge to install the flare/ nozzle on the end, THEN position it. 

Kastolite 30 is a high alumina so it's resistant to HOT caustics like the borax in forge welding fluxes and silicates and it's concrete hard at it's max rated temperature, 3,000 f. It also contains evacuated silicate spheres to make it lighter and provides an increased insulation factor. It's commonly known as a castable, high alumina, bubble refractory.

My forge is working fine with about 1/2" layer of Kastolite on the floor. Getting it smooth is the real trick but it's not a significant factor. 

High alumina kiln shelf is an excellent forge floor, it's even more resistant to mechanical and chemical erosion than Kastolite but it isn't insulating. Again not a significant factor.

To make a nice flat floor in a cylindrical forge I like filling the bottom with a strip of Kaowool with the edges feathered enough to make a smooth transition to the tube walls. Rigidized then plastered with hard refractory. It gives you as much or little flat floor as you wish or the forge diameter allows. It ups the insulation value of the floor and doesn't increase the overall weight much.

Laying kiln shelf on similar Kaowool fill or cutting out a depression for it makes an excellent floor. I'm not sure but I don't think kiln washing kiln shelf is necessary or particularly helpful. That's something I do NOT know though, I may be wrong.

Frosty The Lucky.

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6 hours ago, Frosty said:

Mike's funnin with you, you can slide the burner far enough into the forge to install the flare/ nozzle on the end, THEN position it. 

I wasn't 'funnen' but I did forget that she can open the end of that forge, so as to avoid "building a ship  in a bottle" problems :rolleyes:

6 hours ago, Frosty said:

Laying kiln shelf on similar Kaowool fill or cutting out a depression for it makes an excellent floor. I'm not sure but I don't think kiln washing kiln shelf is necessary or particularly helpful. That's something I do NOT know though, I may be wrong.

It is something of a wash either way (now I'm funnnin). Fortunately there are Morgan K26 insulating firebricks from Thermal Ceramics (look them up on eBay), so the "do or not to do" is yesteryear's choice.

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Hello everyone! Thank you all for the tips and help! I have gotten a lot of work done. I have use fumed silica to harden the cyber blanket as recommended. I also used a 2 inch wide black pipe as a burned port. I have drilled and tapped it in 4 placed equidistant apart and the burner can be adjusted to hit anywhere from the near side floor to halfway up the wall. I used straws taped to the burner to confirm aim. 

I welded the pipe into the propane tank with the edge just past even with the cement. I then used high alumina kiln cement made for 5000 degree kilns to line the entire forge. I also used it for the floor. The floor is even with bottom opening partially to keep the material easy to work on but mostly to close up a bit of the volume as it’s a single burner forge. I also made sure to cement over the lips as advised. I have a little bit of welding to finish to close the seam where I put the two pieces together, but overall it seems to be coming together well. 

The stand is made of angle iron sitting like a point up triangle, 3 pieces. Think an M but with one extra hump. I am cutting in the reverse image of the tank and tacking it to the angle iron. All 3 pieces of angle iron are welded together. 

The burner is a devil forge DFC.

On to some pictures in progress. 

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So I have finished assembly and kiln cement and have now welded the two pieces together. The bead is ugly but it does hold and fill the gaps. Next step is to fire the burner and then do refractory.

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Using a mig, I would suggest turning your heat setting up to 2 (looks like you're set at 1). If you don't feel comfortable turning the heat setting up, turn your wire speed down to 30ish. You also may not have a good ground. I think running at 2 with a wire speed of 35ish will yield the best results as long as you don't dilly dally (or you will have blow outs!). Or you can just do you, I'm just a dude on the internet!

 

Having just typed that, my suggestions are from experience with Miller products. I don't think it should matter too much, but the wire speed may be a touch different. It wouldn't hurt to get a couple of scrap pieces from your door cutout to practice on till you get the bead to run.

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Ok, I ground down all the bad welds and after a lot of practice on scrap went for it again. This time I actually got the the puddle to form and come with me. It seems to be a lot better. 

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A LOT better! Those welds will last the life of the forge! A few more projects and you will be laying some pretty beads down. If you need to weld anything else, weld dot com has some quality, easy to understand tutorials that will help a lot. It's a good resource with some great teachers. Glad your forge is nearing completion!

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What was the brand on the 5000 F kiln cement? That might make an interesting binder material.

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Thanks guys! The kiln cement is sold by Marjon ceramics in Phoenix. I can’t remember the name. I will see if I still have the bag.

edit: it says KCD 5 kiln cement. I can’t find it online. 

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