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AÂ Bramblebush Workroom Project
Foundry Work & Casting
A compendium of miscellaneous information
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Page - 02
Jan. 7, 1999 - Good to get an idea of your system. I use the R&R Primecoat, fused silica flour, no prewet (so only one drum of slurry), zircon for the first 2 sandings (applied by hand/seive on a table) and the balance (usually 7 coats total) of the 30-50 mesh fused silica (applied in my handy dandy home made fluidized bed usin that I am supposed to get some picts. and instructions on how I made it on the site somewhere,,,,,, I am getting close to getting this together (finally!!)).
Where do you get straight old coloidal silica in larger quantities? R&R????
I know R&R offers the Fastcoat in 5gal. buckets for "trial" work so I would thing they would offer Customcoat that way too. I set up a friend in Arizona a couple of years ago, with 5 gals. of Fastcoat and enough sand and flour to use up the 5 gallons and it was under $200 for all of the materials. I think I will be on the phone tomorrow (800-800-7496) to talk with them about getting a bit of the Customcoat to try. I will also ask about the zircon vs silica on the first couple of sand coats and see what the pros and cons are and post back tomorrow or Friday.
Also, if anyone is interested, Bob Pawlak at REMET (another mfgr of shell materials) would be a good person to call (800-445-2424) to see what is available in these sorts of materials. Bob and I talk every month or 2 (maybe he will get a call tomorrow too!!) about shell, this list, a chat on shell in the near future, etc. I have not used their products as I learned and started with R&R materials, but one of these days I will (you saw it in prine here on this list Bob!!!) try some or REMET's materials. Just so dang busy right now to play.
Great thread,,, learning lots and getting ideas (dangerous!).
John Dach
Jan. 7, 1999 - Here I go again......... I am still using a kiln I made 6 years ago using 2 layers of Kal Wool (inside layer high temp, outer layer the lower {and cheaper} temp} supported by 1/2" welded wire mesh. I made a circle of the mest the size I wanted the kiln to be (about 3 1/2 feet across) and 3 feet high. Then I cut the KalWool so that it fit nicely inside the wire frame. I bought some ceramic tubes (look about the diameter of a standard pencil and they have a hole through them about the diam of a small wooden match) that are used (I think) for kiln element wire supports. Got them from a ceramics supplier. They are about 6" long and cost about %1.50 each.
Scored these with a metal file every 1.5 " and broke them over a table edge. Took 10" (approx) pieces of heavy nichrome wire (small enough to fit easily in the tube holes) and put them through the 1.5"tube pieces and made "staples". Poked the 2 wire ends/staple legs through the Kal Wool to the outside wire mesh frame and bend the nichrome wire "staple" legs over onto the supporting wire mesh to hold the Kal Wool in place.
Made a lid the same way but added a 1/2" angle supporting frame to keep the lid from sagging and to attach handles to for lifting off and on the kiln. If you need some extra height, make one or more rings for KalWool and wire and set these on top of the main ring to increase kiln height. This whole mess is simply set on a layer of fire bricks (filled the cracks with sand) that are set on the ground.
Everything for this kiln cost less than $200 and it has lasted for 6 years (many of those years it has been outside with just a piece of plywood over the top to try to keep the rain off (85" last year!!!!!)). I use a 2" black pipe for a burner, with a $13.00 Conair hair drier for draft, stuck in the end, and a piece of 1/2" iron pipe that I closed off and drilled a 3/32 or 1/8" hole in the side for a gas nozzel.
I use air fittings for connections, ball valve for gross gas control and a needle valve for fine tuning/"preset" gas output. All of the fancy stuff is nice but this "home made" stuff has been working for years and is cheap to make and easy to repair.
I am making a KalWool burnout kiln that is elevated, with a "door" that will open to receive a "cart" on wheels full of shells for dewaxing and or burnout. I will probably end up putting in a bit of fire brick to help distribute the flame/heat, and to act as a heat sink for dewaxing (pre heat the kiln/bricks so that the kiln/shell temp can get hot enough fast enough so as not to crack the shell.
John Dach
Jan. 7, 1999 - Go here http://php.indiana.edu/~jparment/tour11.jpg to see a picture of my kiln. It is essentially a big crucible furnace with a hole in the bottom so it serves two functions. I use it for dewaxing and burnout.
Interior dimensions are 42" dia and 60" high. Temperature variation top to bottom at 1600 is 10 degrees. It is warm to the touch on the outside at temperature and very efficient. I can fire it for 2 hours for about $8.00.
It has two Eclipse high velocity burners, tunnel mix for a large turn down ratio so I can get both high heat and low heat from the same burners. This is important because for dewax you want a low (450) temp with very short flame so you don't set the wax on fire. At dewax I use a large funnel shaped thingy to direct the wax through the hole and into a pan that has a little water in it.
For burnout we plug the hole and fire it up to temperature. I work from ss baskets that are lowered into the kiln after we have preheated to around 1500. This insures an almost smokefree burnout since I also really pump the air into it.
The construction is 1/4" steel shell, fiberfrax outer insulation, firebrick liner, cast refractory floor and lightweight cast refractory lid. I built this kiln from scratch and it has lasted 10 years.
I would think seriously about using a lightweight castable refractory for a kiln. It's easy to use. the only problem with it is you have to go through a high temp curing cycle. AP Green makes a refractory that has a shorten cycle called Plus. You can use sonotubes for pouring forms. Since you are only pouring 30 pounds a shot, you do not need a big furnace. The problem with exposed Fiberfrax is it's a health hazard, especially after it has been at a high temperature a time or two. I use it only as a backing insulator.
Daniel Rhodes is the dean of kiln builders but your interests are different from ceramics firing. Don't know about the other one. You want fast heatup and ceramics kilns are not built for speed.
This is a big subject. Ask some more specific questions and I'll try to answer them.
Mark Parmenter
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