Forge building question

S

swampwolf

Joined
Jul 24, 2004
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19
I am getting the goods together to build a forge and I have a question about the inside lining. It seems to me that the most popualr material by far is the "wool" lining. Being a guy that likes to expirament with EVERYTHING, I have been wondering. Say you were going to use an 8in pipe for your forge body and instead of putting in wool, you got a smaller peice of PVC(say an inch or smaller od than the inside of the pipe), put release agent on it, put it inside the forge and poured in 3000 deg. morter around it to form the lining. Would it work? Would the morter insulate enough? Would the morter need to be re-enforced with something? If so, what could you re-enforce it with? Just curious.
 
It would work. That's how I made my small coffee can forge. I used a wax core which I melted out after the refractory cement hardened. But I spent $14.00 just for the small amount of cement used.

The wool is popular because it is a lighter, better insulator and cheaper. I made a larger forge with two layers for the same $14.00.

Trust the knifemakers here... if it can be made cheaper or easier, they'd found it by now.
 
The mortar will tend to hold the heat in better. It will take a lot longer to heat up, and longer to cool down.

I once built a forge with a big piece of high alumina kiln shelf for a floor, and it would take half an hour or even more before the kiln shelf heated up enough to do any real work. The mortar would act in the same way, except it might take even longer to heat up.

I would not build a forge in the manner which you suggest, since I'm impatient and like to get to work quickly after starting up the forge.
 
I have seen forges built this way that worked good, but you have to use the right kind of refactory, the light weight hight temp stuff and they mix stainless needles with the refractory to help hold it together, kind of like rebar in concrete. But, I have been making and using forges for over 15 years and the one I like the best by far is the vertical "Don Fogg type" forge, all the info is on Foggs website, very good forge for damascus.

Don Hanson
 
If you are going to try the cement method do not forget about the gas inlet hole. I would think it may be a problem getting a smooth hole once it was dry.

I use the wool but I would be interested to here how it turns out if you go that way.
 
I wouldn't use a refractory mortar alone for a forge lining...it's not robust enough in my opinion. If you want to pour a hard liner, get a durable castable refractory such as Mizzou. No need to add stainless reinforcing needles to it for a forge that small. I would, however, recommend making the walls at least 2" - 3" thick though for better insulating properties....which would mean you'd need a larger forge shell. No matter what you do, though, with a castable liner it's going to take longer to get the forge up to temperature.

I usually only recommend a full castable forge for someone who is going to be making a lot of Damascus in it...and then, only as a second forge. Build yourself a small (like you're planning) forge out of a good quality ceramic fiber blanket material such as Inswool and top-coat the Inswool with your refractory mortar. A coating of ITC-100 will also help to improve the efficiency of the forge.

I'm going to be out of town for a bit and won't have access to email or the web so I won't be able to answer any other questions if you have any about what I mentioned, but here's a good resource for info on building forges...check it out and see what others are doing...:

http://ForgeGallery.EllisCustomKnifeworks.com

Hope this helps some! :)

-Darren
 
Ripper said:
swampwolf,

These links are more foundry directed but might help you out some:

http://www.backyardmetalcasting.com/bucketfurnace1.html

http://www.john-wasser.com/NEMES/MakeICR.html

Regards,
Greg
Click to expand...

...I checked out that John-Wasser.com site and just wanted to add a note based on my experience... I've sold a good bit of refractory material to people who went the home-made route first. Quality refractory materials are cheap, especially compared to your time and having to reline a forge because it didn't work out the way you wanted it to the first time... whether it be from me, or one of the other suppliers of tried-and-true refractory materials, get the right stuff and do it right the first time...

:)

-Darren
 
That's probably good advice Darren, but some people have to find it out on their own :) I still have some pearlite and furnace cement around here that I meant to try, but ended up going with the fiber blanket instead.
Regards,
Greg
 
Thanks so much for all your posts folks. If yall say the blanket is the best way to go, then thats what Im gonna do. Tell me about this insulation. Ive read that it is "hazzardous" if you breathe the fibers. In what way? Like fiberglass? Like asbestos? Im sure my son will be using this forge too and that concerns me. What kind of safty measures should I take when installing it? Will I need to wear a respirator while using the forge?
 
swamp,
I use a thin shell of refractory covered by a cerawool insulation. The shell is cast and about an inch thick. with proper care this type can last 5 yrs or more. You get good heat too, I can heat 20 lbs of steel to welding temp in 12 min. Mine oly takes 25 min to get to temp.
Del
www.ealyknives.com
 
the 3000 castable refractory soaks up a lot of heat before you can do any work in it. and i do mean it soaks up a LOT OF HEAT.If you want to use refactry go for a lower rated one 2300 would be better, koalite is one I think.

I built one with mizzou it would take 4o minutes to come up to forge heat and would not weld at all using the same burner i had in the kwool lined forge. same size and everything.

Use the k wool rigidizer on the kwool even if you apply another coating to it.
it will last longer and present less problems for your lungs.

use a blu ram,alumin coating or mullite shelf int he bottom of the forge. This prevents further dammage to the wool lineing.

My .02 based on the forges I've built and things I've learned from the forums.

The hazards of kwool come in long term exposure just like anything else you breath. take precautions to avoid breathing it on installation, personally different folks are more susceptable to different irratations. I take more precautions when working walnut thanI do the kwool, i'm alergic to walnut.

Folks that work the stuff for a liveing have problems, remeber the popcorn lung thing a while back. Workers in the popcorn industry were being adversaly affected by the dust from the corn.


Cover the wool and protect it and in my opinion it doesn't pose a health risk.

look up "koawool MSDS " in google.
 
I usually wear my respirator when I'm cutting wool and installing it in a forge though I have also worn just a dust mask before. I also try and do this outside. Once its coated with something like satanite or ITC-100 you should be fine.

Another option for a horizontal forge is a cast or rammable refractory in the lower third or so of the shell and wool in the upper part. Kinda the best of both worlds thing. It will heat up quicker and will be resistant to flux attack in the bottom where the stuff will tend to pool.
 
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