Hot Water Heater Furnace

[Bovine]

I have had Dave Gingery's book on charcoal furnace construction for some time now and I recently re-read it for foundry information.
Building a charcoal furnace sounds like a rather simple affair but I am struggling to find materials locally.
After racking my brain for a while, I remembered my old 50 gallon electric water heater sitting under the steps.

 

[Bovine]

Disassembly was pretty straight forward. Popped the top and bottom and opened that thing up like a gutted trout.




Pneumatic shears cut the light sheet metal and the insulation (only about 1" thick) proved no real match for me.

 

[Bovine]

Diameter is 16 inches and height is no problem.

 

[Bovine]

I think the top will remain the top and I can reuse one of the lower holes or drill another for air.



I still need to answer the problem of refractory material though. Local web searches are not turning up anything so I think I will have to go old school and make some calls.

 

[tel]

Any place that sells potter's supplies should carry castable refractory, or be able to get it.

 

[starnovice]

I still need to answer the problem of refractory material though. Local web searches are not turning up anything so I think I will have to go old school and make some calls.

Just this thread for an idea. I have used this guy's furnace and it works well.

http://www.homemodelenginemachinist.com/f36/chimney-liner-kiln-10819/

Also, BudgetCastingSupply.com has refractory. I have not bought from them for a while but they were good when I did.

Also, forget charcoal and go straight to a Rhiel Burner. Google for plans. I did the Ginger Foundry and the charcoal is not worth it.

Also, (sorry I keep thinking of things) remember some day you will want to do brass so it is better to build a furnace today that will handle the extra heat then to rebuild later.

Pat

 

[jasonh]

Any metal drum of the right size can be used. You don't need much wall thickness on the metal. I used a medium sized garbage can I bought at the hardware store. I had to boost the lid thickness to accommodate more refractory, but that is all. The important thing is to build the furnace to fit the crucible you want to use. Say - an extra 2 inches all around between the crucible and the furnace wall. Then another 2-3 inches of refractory all around. Do the math and you'll know the size of your furnace.

Refractory wise the sand/fireclay mix suggested in the Gingery books will probably be good for 50 burns but does tend to wear out. Keep in mind also that castable refractory is quite heavy- so have a plan for moving your furnace if it is big. (Kastolite is lighter than Missou - but is still quite heavy).

My story - I've been using a sand/fireclay, charcoal powered furnace for my Aluminum casting needs. I can make a #6 crucible full of molten Aluminum. Charcoal is simple and cheap, but fuel management is a pain.

My next step is to upgrade. Kaowool + firebrick for the furnace. Oil/propane burner. I'd like to melt bronze, brass and iron.

Jason H.

 

[Bovine]

Beside about 10ozs of sand, there were corroded remains from heater elements of the past 15 years.

 

[Bovine]

Dissection is complete. This housing is big. I will do the math for a 3" wall all around to prevent too much weight but I think this will leave a large chamber for the crucible that may present heating concerns.

 

[Bovine]

Any place that sells potter's supplies should carry castable refractory, or be able to get it.

Thanks Tel, it appears I need to travel to Seattle to get it. Can I pick you up a coffee?
Bovine

 

[Bovine]

Please be patient while I try to post math equations without the ability of using any math functions.

My furnace has a body of 16"hx16"w. The top is 16"wx3"h.
I will figure volume for top and bottom and then figure for the body minus the bottom.

volume of a cylinder is Pi*radius squared*height
3.14 x (8x8 x 3=603 inches cubed. since top and bottom are the same I can multiply this by two= 1204 inches cubed. I want cubic feet so I will divide by 144= 8.375 cubic feet for top and bottom.

Now for the body. The formula for the volume of an annulus is:
Pi(d1 squared-d2 squared)
Pi(64-25)=3.14 x 39=122 in sq.
For cubic inches I multiply by height, 13" (body minus the 3" bottom)
1592 inches cubed divide by 144 to get cubic feet=11 cubic feet.
That is almost 20 cubic feet of refractory!
Can someone please check my math?
I have to drive into the city to pick this stuff up and I am hoping to make this work on the first try.
Thanks
Bovine.

 

[Dave Sohlstrom]

Bovine
I think you have your cubic inches per cubic feet wrong. 12X12X12 =1728 cubic inches per cubic foot.
When I run the numbers I come up with .69 cubic feet for top and bottom and .92 cubic feet for body.

Dave

 

[Bovine]

Dave,
Thank you, that makes much more sense. I got my brain wrapped around the axel on the formulas and missed the cubic portion of the volume.
Much appreciated
Bovine

 

[jasonh]

lid = (3*8*8*pi) = 192 * pi
body = (3*8*8*pi) + (13*8*8*pi) - (13*5*5*pi) = 699 * pi

total = 891 * pi cubic inches
total = 891 * pi / (12 * 12 * 12) cubic feet
total = 1.62 cubic feet

I'm with Dave on this one.

Jason H.

 

[100model]

Bovine

Hot water heaters make excellent furnace shells, I have been using them for years. Kaowool is the furnace lining and waste oil is the fuel I use. Forget about charcoal use gas or oil. Have a look at my furnace, [ame="http://youtu.be/t5kP1wika4k"]http://youtu.be/t5kP1wika4k [/ame]

 

[skyline1]

Hi Bovine

Propane is fine aluminium I use a Sievert burner with a dia of about 1 1/4" but for iron I use old fashioned furnace coke. It's getting a bit more tricky to obtain now but the smokeless boiler fuel known as "Sunbrite" works very well. Sweetalk your local coal merchant and see if he can get you some sunbrite singles. Blacksmiths use it in coke forges so there is still a bit about. Give it enough blast and coke will get hot enough to melt cast iron with ease in fact it will melt steel I once did so accidentally.

In the U.K. Purimachos Ltd have a range of suitable refractory materials I dont know about other parts of the world though

Regards Mark

 

[Bovine]

I made the trip to Seattle Pottery Supply today and purchased 100lbs of Alsey Hi-cast. After getting home, I went to the website and read that much only makes .8 cubic ft. I also bought some bentonite, maybe I can add some of that to reach my needed 2 cubic ft. Hi-cast is rated at 2700*f with a heavy duty cycle.

 

[Bovine]

I cut these two pieces for a crucibal. 4 inch pipe, 6 inches long. I cut a solid steel disc for the bottom that I still need to weld.
I still need tongs to handle it

 

[Bovine]

100Model,
I like some of your inovations. Such as the lid lifting lever for your furnace. The other smooth operation is the crucibal dolly you use for safe and accurate pouring.
Thanks for sharing.
I have been scratching my head over the location of the tweer (I know the spelling is wrong) I assume it enters at the bottom of the chamber, but should I aim it directly at the crucible or do I aim it at an angle against the wall of the foundry.
Any input would be appreciated
Bovine

 

[Herbiev]

100model. Great video and superb castings. Where in Austalia are you and where did you get the Kaowool?
TIA Herbie