refractory cement help!

[Jake Bissen]

So I've been looking around trying to figure out what exactly to get to cast (or alternative) the inside of my sheet metal forge.

http://www.anvilfire.com/article.php?bodyName=/plans/ething_forge/sheet_metal_forge.htm

It's basically this. I have firebrick to use, but doesn't really work for this design.. top or bottom. And I don't want to spend 100 dollars on like 100 lbs of cement. I only need a little.

Anyone know where I can get what I need, and what exactly to use? This is all that's holding me up on finishing the project so far.

The top cone or torch doesn't ever have anything put in it so it doesn't have to be heavy duty. The bottom piece does take a lot of abuse those. I'm also trying to do this as cheap as possible (I'm making this forge to save from spending money on acetylene as it is).

Any help would be appreciated!!

Thanks,

Jake Bissen

(AKA armor guy)

[Eric Berna]

A cheap alternative to refectory cement is ceramic. Form the shape out of clay, and run the forge to fire the clay. 

I made a backyard aluminum melting furnace out of clay I dug out of my back yard. The frame was a metal 5 gallon bucket. The insulating wall was about two inches thick. To give it extra insulation I made the ceramic layer rather thin, about a half inch, and filled the gap between the ceramic and the bucket with perlite. 

Although you could buy quality clay from an art supplier, you don’t need the best quality clay. Maybe the MMS ceramics area has some old scraps they’ll let you have. Or you could just get some kitty litter. The basic cheap stuff is just bentonite clay. Mix with some silica sand and some water, and you’ll have cheap refractory material.

Eric Berna

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[Jake Bissen]

what kind of temperatures can it handle? upwards of 2000?

thanks for this though! 

[Eric Berna]

Depends upon the type of clay, but most will easily handle 2000°F. 

On Jun 10, 2015, at 11:27 AM, 'Jake Bissen' via milwaukeemakerspace <milwaukee...@googlegroups.com> wrote:

what kind of temperatures can it handle? upwards of 2000?

thanks for this though! 

[Jake Bissen]

I did find that potters clay is used often, but I found this so I'm wondering if this will work?

I found this which is listed as "fireclay" on home depots website but noone carries it around me but lowes does.

http://www.lowes.com/pd_10367-13040-10367_0__?storeNumber=2554&selectedLocalStoreBeanArray=%5Bcom.lowes.commerce.storelocator.beans.LocatorStoreBean%404b464b46%5D&productId=3110273

then portland

http://www.homedepot.com/p/Unbranded-94-lb-Gray-Type-I-Portland-Cement-100013/202323979#specifications

perlite

http://www.homedepot.com/p/Miracle-Gro-8-qt-Perlite-Mix-74278430/204502291

and silica

http://www.lowes.com/pd_230025-286-196301_0__?productId=3646422 

I'm doing this refractory recipe

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

anyone know if these will work? I don't want to buy them all and then it crumbles or explodes or something. Fireclay is not a very common thing to find...

[Eric Berna]

I don’t have experience with this particular recipe; it should work. I do have some comments on your choice of materials. 

Don’t use the Miracle-Gro perlite. It’s enhanced with their plant food, and theres no telling what those chemicals will do to this concoction. Try to find a generic without any enhancements. Also, perlite is puffed volcanic glass. It’s benefit as an insulator is the air pockets in the puffed material. So you want to keep this mixture rather dry, so the cement and clay particles don’t fill in the perlite. Also, you’ll want the mixture to be rather porous, so that the pockets of perlite aren’t sealed air bubbles potentially exploding like popcorn as the forge heats.

You really want your sand to be mostly silicon dioxide. Sand sold for making cement mixes can be almost any rock ground to small particles. I don’t know how to tell the difference for sure, but when I made my furnace I bought white decorative sand that was labeled silica sand.

Eric Berna

[Jake Bissen]

Ok cool, so you think that "fireclay" will be sufficient? thats been the hardest thing to find

Jake

[Eric Berna]

Yes.

On Jun 10, 2015, at 3:59 PM, 'Jake Bissen' via milwaukeemakerspace <milwaukee...@googlegroups.com> wrote:

Ok cool, so you think that "fireclay" will be sufficient? thats been the hardest thing to find

Jake

[ironmonger]

Any high temp refractory will withstand the temperature, but unless it has insulating properties the outer shell will get VERY hot. A better material is kaowool or cerawool. A cast able refractory is also excellent. Try Firebrick Engineering or Sprinkman insulation. My casting furnace has paint on the shell... melting bronze inside. The paint us still there.

[Operations Director]

I like meeco's redevil or plibrico refactory cement or Castable refactory cement.
But, it's about $20/gal+.

DL.