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20 pound propane tank forge in progress


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It's been a while and the forge had to go on the back burner for a while. Today we put in the first coating of Satanite. Will let it air dry overnight, then fire it tomorrow. I was thinking of using our commercial heat gun in the burner port which will heat the interior to 300 degrees for the first firing to dry the Satanite, let it cool then use the burner for the next firing..

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Hang a light bulb in it it will dry it out surprisingly quickly. What's the relative humidity? If it's very high it'll take longer to dry, you want the liner warmer than the air.

Frosty The Lucky.

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9 hours ago, Irondragon Forge & Clay said:

The humidity is very high right now around 90% and raining all week one reason for the heat gun set on low.

Ewwwww sweatiness! The humidity isn't 90% here when it's raining. We have to put out sprinklers to prevent concrete pours from drying before they set properly. What's a heat gun cost down there? I'd be more likely to light a few charcoal briquettes and toss them in but I'm . . . frugal. . . . Ish. ;)

Frosty The Lucky.

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I think the commercial heat gun cost $40 at Lowe's ten years ago for pottery work ($60 now). It took about 15 minutes to totally dry the Satanite. I put the Gaco burner in and fired it up for two minutes at 5 psi then turned it off, let it cool down. The second firing was for six minutes and cool down. The last firing was for 15 minutes and I checked the temp with a pyrometer at three minutes and the temp was 1850 degrees which stayed steady so I increased the pressure to 10 psi and blocked half of the rear exhaust with a kiln shelf.

The burner then back burned (kind of surprising) so I think the .0625 orifice is too large, other than that the flame swirls beautifully and the color was bright orange. Next is to order a smaller orifice and apply another coating of Satanite.

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Yesterday was a nice day weather wise, in the 80s with about 70% humidity. We applied the final coat of Satanite and let it air dry overnight. A local propane dealer (next town over) had an orifice for the burner. It had a really small opening (.025) tried it a but it wouldn't stay lit. I drilled it out to .036 and it worked. The burner would light at 10 psi and after warming up I could back the pressure down to 5 psi.

Did several short burns to set the Satanite then ran it for an hour and I think it's running a little lean. Couldn't get any good pictures because of it being sunny out but the color looks about yellow to me. I heated a piece of 1/2 inch rebar to forging heat in about 5-10 minutes but it seemed to take longer than my coal forge. No problems with back burning yea.:)

The next step is to cut the kiln shelf for the floor and coat the interior with bubble alumina, which should raise the interior temperature. After that I might consider drilling the orifice to .042 (my next drill size up) if it's still running lean.

Tomorrow we have a BOA meeting and I'll ask some of the propane folks what they think about that idea.

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Everything you've written so far sounds like you're on track, thus far. I would slow down a little bit about doing anything further with the burner, at this time, and continue finishing the forge, instead; just my two cents worth. Why? Because we often overbuild the burner, when it isn't the problem. If your burner is running right--and that includes anywhere near close to right--you are more likely to change the burner closer to wrong, by fiddling too much without bringing the forge closer to right, instead.

In a fashion, you can think of your forge as having two flames: the burner flame, and the forge atmosphere. No, the forge atmosphere isn't really a second flame, but it is helpful to think of it that way, if you want to end up with a proper radiant oven.

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NO MORE BURNER ADJUSTMENTS! At least not till you finish the forge, the back pressure will likely richen up the flame anyway. However did the steel form scale IN the fire?

That't going to be one HOT unit when you finish.

Frosty The Lucky.

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I got some scale off the rebar but no more than when I heat it in the coal forge. The heat blast out of the forge is pretty intense, heating a bar about three feet long without a stock rest is uncomfortable holding it up. Never using a propane forge, I didn't know if that was normal or not.

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15 hours ago, Irondragon Forge & Clay said:

I got some scale off the rebar but no more than when I heat it in the coal forge. The heat blast out of the forge is pretty intense, heating a bar about three feet long without a stock rest is uncomfortable holding it up. Never using a propane forge, I didn't know if that was normal or not.

Nooooo, my question is. Did scale form IN the forge? HOT steel always forms scale when you take it out of the fire but it shouldn't form IN the fire. In a solid fuel forge it probably means you have the steel too close to the air grate or tuyere. In a gas forge it usually means the burner is running lean. With a forge as wide open as yours it COULD mean the flow patterns in the forge are drawing outside air in through the openings.

For now don't worry about the openings just be aware they will prevent you getting more than close tuning the burners. It's not only possible it's almost unavoidable to have both reducing and oxidizing atmospheres in the same furnace. 

MAN I hope I didn't just confuse things with TMI! 

Frosty The Lucky.

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Today we put in the bubble alumina, hope it wasn't a mistake. That stuff is very difficult to work with to say the least. We could only get it about half way up the sides, doubt we will use it again. Letting it air dry overnight and will fire it up to cure it tomorrow and hope it sticks to the Satanite.

 

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How wet did you make it?

Kast-O-Lite is water set it doesn't dry, it hydrates like concrete. Mix a smaller amount than you used and spread it on the bottom of the tube. When you feel it starting to set use a dowel or similar and "hammer" it smooth. Rinse out the mixing bowl and clean the tools while it sets in the forge, say another 20-30 minutes. Mix up another batch and spread it touching the now set section. Repeat till it's lined each set section holds the next. 3-4 iterations does the job. Don't smooth the edges where one section meets the next, the rough edges will key together and make a good bond.

Frosty The Lucky.

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We mixed it to troweling consistency like concrete, don't think it was too wet. The bubble aggregate was larger than expected though and it did not cover as much as expected. What I did was tamp the bubbles in with my fingers to get it as smooth as I could, like tamping concrete to get the aggregate below the surface.

I figured it was a chemical reaction that set it, like epoxy because after a couple of hours it was hard as a rock.

This morning we fired the forage and could tell the difference in heat right away even though only half the forge was coated. The same piece of rebar reached forging temperature in three minutes and after six it was at high orange (almost welding heat).

Debi figured out that it will have to be done in sections as you said so we will order more and coat the rest now that we know how to work it. Still contemplating applying a IR reflector like Plistix if we don't reach welding heat after the exhaust ports are closed up. The test this morning was with both ends open. 

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Debi read that page and laughed then said "we have every one of those ingredients including VeeGum. Then she said I'm through with experimenting (from her pottery days) and will go with what works so more bubble alumina is on the way.:)

In the meantime, I made a folding stock rest that attaches to the forge cart.

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Here is the stock rest like on some old coal forges, works well and is out of the way when not needed.

 

 

 

As a footnote, if you are working with kiln shelves, do not let them fall off the table because they don't bounce.:P

This one was going to be the back door but because of my clumsiness plans have changed.

http://i66.tinypic.com/2ni2x6w.jpg

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