Forge lining help?

T

Tinman 9339

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Oct 26, 2016
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I try not to post anything that has been gone over a million times but, that's the inherent problem. There are a million different opinions on here so, here goes. I am building a two burner forge out of a small air tank (13"x24"). I was given 2 boxes of insulfrax ceramic blanket. 1 box of 1" and one box of 2". I plan on doing a lot of forge welding so I need a flux resistant lining that can withstand high temperatures. I can't figure out which combination is best. Kast-o-lite with plistix? Rigidizer with Satanite and itc-100? Itc-100 with flux resistant liner? Etc. Please help
 
In the same process myself right now. I am doing ridgidizer, satanite, bubble alumina on the floor.
 
I read a lot about this too before building my most recent forge. It seemed that the best option is a vertical forge if you're doing a lot of forge welding...however if you want to go horizontal, a lot of people say that the Castable refractory is more resistant to flux than other materials, and also adds a bit of thermal mass inside of the forge to even out temperature a bit.

Some people make removable floors that can be replaced, in which case I'd probably use Castable as the material for the floor. Some people even use kitty litter to catch the flux and replace that.
 
Also, I would highly recommend going shorter than 24 inches unless you plan to do a lot of heat treating of larger blades inside your forge. I kept wanting to keep mine long despite recommendations to go shorter, and lo and behold, it's longer than I need. I'd shoot for about 18 inches with a port in the back so that if your blade IS longer than the inside of the forge, you can pass it in and out.

Also shoot for a smaller interior size. Mine is a 6" interior and feels quite large. In the end it's a great forge but in hindsight it can always be better! I'd say 18" long for a 2 burner with about a 4-5 inch interior. And pay most attention to where the first burner is because that's the area you'll use the most.

The second burner is only necessary in certain cases like pre-heating and heat treating, and if you're doing stacked billets for Damascus. A lot of the time you'll want to only have one burner running, at least in my experience. Once the interior is up to heat, the first burner will heat a large enough area of the blade for what you can work with the hammer. Heating more of the blade than what you can actually work with the hammer before it cools is just unnecessary, especially as the blade gets thinner as you work it, there will be less and less of an area you can work before it cools. Oh, and you'll also save more on gas [emoji106]
 
I had heard that you can block off of the forge with fire brick and only use the front burner for small items. Has anyone had any luck with this?
 
I had heard that you can block off half of the forge with fire brick and only use the front burner for small items. Has anyone had any luck with this?
 
Yes I also highly recommend using bricks for the front. Weld on a steel "shelf" long enough to where you can fit two bricks lengthwise so you can slide them apart to have an adjustable-sized door with a third brick on top of those two.
 
For my forge I decided to use ITC-100 over Satanite over 2" Kaowool. Floor is a section of 3/4" hard kiln shelving that is kiln washed and skinned with satanite, with wool under it for improved insulation. I don't know that is significantly better or worse than any other combo, but it was an easy set up and replacing the floor should not be hard to do should the shelf section wear our. It got hot enough to melt the cast iron burner flares I initially had on it in a hurry. That's a good sign right?

I'm also curious about shutting off individual burners in multi burner forges. If you were to do this do you need to block off and plug the unused burner to prevent heat going up the mixing tube? Is just closing the choke off (assuming you have one) sufficient to prevent air flowing back up it, or would you need to do something like pack ceramic fiber into the nozzle at the bottom to stop heat traveling up it? I'd hate to melt my gas orifice or something because of the chimney effect.
 
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I would always remove a burner when not being used. For that matter, I remove them as soon as I shut off the forge. Heat is going to transfer back through the burner and likely ruin any teflon tape used to seal the threads of various parts of the burner, especially when other burners are still "on".

If your cast-iron flares melted, you probably had them way too far inside the chamber. On my forges I don't use any flares, the chamber opening for the burner should act as a flare. If you need a flare, it should still be a little bit back from actually being in the chamber.
 
My burners are installed coming up at an angle from the bottom right side of the forge so the rising heat doesn't seem to be much of an issue with them. That, and, it's a blown setup and I have a good 14" of steel tube between burner nozzle and to where it connects to the threaded junction so it's really unlikely heat will travel far. When not using both burners I just use the sliding back wall to cover the other and it does the trick.

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Great info so far. Thanks guys. Do I have to install the burners into a sleeve welded to the forge out can I just weld the burners straight to it?
 
I've found that in trying to get my forge set up and dialed in I've removed the burners at least a half dozen times to move or tweak or test something. I suppose if you had a design you know works it wouldn't hurt to have the welded on. But at least in my case building my first gas forge of this style it was much better to have them removable.
I'm using two pieces of angle iron welded the forge body, and then use hose clamps to secure the burners to the angle iron supports. It's simple and is working well so far. One mistake I did make (so you don't make it as well) was that I sized the hole through the forge body to small for the stainless burner flairs I bought to pass through. This means I have to install the flares or mixing tube from the inside of the forge, and then screw them onto the venturi. This was no big deal before I put my Satanite in, but now that I have a shell built up the set screws on the burner flares stick out to far to pass through in either direction. So I've effectively trapped them in unless I want to chip out clearance in the Satanite to get them out. I think I would have been better off with a larger hole on the outside, and then back filling around the flares with wool to seal them in.
 
OK, here's a quick list of five reasons

Because drilling three holes and using bolts is quicker than welding
Because you want to make sure it's the "right" place, and you might weld it into the wrong place
Because it's easier to move if they aren't welded
Because burners don't last forever, especially if you use flares
Because you'll get a little extra venturi action around the port, helpful with larger BTU burners


Tinman 9339 said:
Is that necessary though? If so why? Just trying to understand
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