Forge lining question

redeagle66

redeagle66

Joined
May 30, 2011
Messages
152
I have a square steel shell that I can line with kaowool giving me a square chamber about 4" per side and 12 long. I would like the chamber to be round but I'm not sure I can get it round laying a refractory over the wool by hand.

My question is about lining it with satanite or some other refractory material. I have not worked with them before (my first one just uses fire bricks). If i stand the frame on end and put a 3.5" diameter tube centered down the square chamber, would it be possible to create the lining using a pour? I don't know if the refractory material is thin enough in consistency for that or if the resulting skin is too thick over the wool.

Any feedback or recommendations is welcome.
 
Lots of people use castable refractory (not satanite, which is a refractory coating) but I'm not sure about using castable refractory over kaowool... Someone else will need to chime in on that one.
 
First, make the square round.

Useing satanite or a castable refractory like castolite. Put a cardboard tube in the square that just fits. Build it up with layers of cardboard until it touchs the sides, leaving open triangular corners. Tape off the bottom and pour the refractory in the voids. After it cures remove the round tube. Now you have a round chamber to put the inswool in. After installing the wool, coat the inswool with a 1/4" of satanite. This will make a well insilated round chamberforge with a square outer shell.

I have a ton ( literally) of castolite. Send me a PM with your shipping address and I will send you a flat rate box filled with plenty to do this job.
 
Stacy E. Apelt - Bladesmith said:
First, make the square round.
Click to expand...

Stacy, Thanks a lot for the idea. I have some leftover 8" concrete form tube that will just barely fit. If i take a 1/2" slice out of it and tape it shut i could get a nice tight fit into the frame so i can pour the corners into round.

Just out of curiosity, do you think its better to have four separate corners or make the tube slightly smaller to leave a thin skin around the flats so i get a monolithic shell? I don't know if it matters structurally. I prefer your idea because I want to save weight, which is why I'm going with wool instead of bricks now.

I greatly appreciate your offer of the castolite.

Regards,
Al
 
It shouldn't matter a lot, but a full sleeve may be stronger than four corners. The four corners suggestion was because you didn't seem to have much room to spare in the piece of pipe you have.


Optimally, you would use pieces ins-wool to fill the corners, and then a roll of wool to make a tube, and then a cast liner that is 1" thick inside the tube of wool. The liner would have an inside coating of ITC-100. This would be a very high grade forge ... but is considerably harder to build than it sounds. Few people go the route of a cast liner. Building up satanite directly on the wool is simpler and nearly as efficient for most knifemaker needs.

I'll get the Cast-O-lite 30 out this weekend.
 
Atlas Knife Company said:
Wax paper, two layers. Think about it.
Click to expand...

Ah yes, the voice of experience. Thanks for the input. I think we've traveled some of the same path to wisdom (aka learning from our screwups, haha). Many moons ago I bedded a rifle and forgot to cover a section with release agent. Now I always try to consider how to get out of any situation I get into.

Stacy,
Many thanks. I might try that in a future build just as a challenge. I want a minimum 3.5" working chamber so don't think i have the clearance now. In a forge like that, would it be a 2" roll of wool outside the casting or is 1" acceptable?
 
Yes, to make a good cast refractory forge, 2" of wool around a 1" thick cast liner is about right. The cast refractory is what absorbs the heat and holds it, the wool is what insulates the liner and keeps it hot. A simple shell around the insulation and refractory is all you need. A piece of sheet metal that has clamps or is just screwed together into a cylinder is the best wrap type shell. Obviously, the weight of the heavy liner will try and crush the wool if some sort of stand off pieces of fire brick aren't added on the ends. One great thing about soft firebrick is that it can be shaped into curved pieces and seal the ends of any forge buiild.

A heavy cast refractory type of forge works best as a vertical type, because you just wrap the liner in a two or three layers of 1" wool ( one long piece is best and easiest) and then wrap a sheet metal shell around that. If using a solid pipe type outer shell, cut it in half and hinge it, then use a screwed down latch or straps to hold it closed. Place on a fire brick base and fill the bottom with 3" of kitty litter. Make a cast top with a wool or fire brick cap and you are done.

Whenever you cast anything in a form, the form needs to be lubricated and removable. I like to cut PVC into three pieces and tape together. I often make end caps from wood that keep the PVC form together. Unscrew the end caps and pull the liner out one piece at a time. I use vaseline as a release most of the time. On metal pieces that need to be released, a few coats of paste wax also work well. Other methods use wrapped newspaper, saran wrap, and waxed paper.
 
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