Some questions about foundry building

[binaryclock03]

Hello all, first post here.
Got some questions for you more experienced peeps.

I'm a student who's quite interesting in melting and casting metals. I started with the whole king of random bucket one with a simple steel foundry I made in shop class. Now I've moved onto my next foundry design which is a little more professional. Its a simple hexagonal steel bin thing I welded together with ceramic wool on the inside for insulation, and yes before you say anything, I've sealed the wool and I still always use a respirator with it. Currently I'm finding that the ceramic wool is slowly melting and degrading, and most importantly, I just pulled out the stuff lining the bottom of my foundry after it melted to my crucible :/ . I was wondering if you guys could suggest some kind of hard refractory to put at the bottom to place my crucible on. I've been looking at satanite. Put a bit at the bottom and some lining the ceramic wool to protect it a bit. And then seal all that with ITC 100.

Is this a good design? (Im using propane)
If not what is?
Also, where do you guys get your supplies. The only good place I can find to sell this stuff is charging like 40 dollars in shipping for 5$ of stuff. (I'm in the GTA Torontoish area)

Thank you for reading (and hopefully helping).

 

[kevin.decelles]

I've typically used hard fire brick as a plinth at the bottom of my furnaces if/when I need to 'raise' the crucible. You could also try making or buying some refractory. I used this stuff this summer Amazon - refractory and worked ok, not cheap ($47) but free delivery if you have prime.

I've tend to shy away from ceramic blanket unless it is an intermediate layer. I've always used fire-brick and/or castable refractory as my liner. I've built two furnaces in 20 years and they are still going.

 

[binaryclock03]

The only problem with that stuff is its only rated to 1200 degress. I'm looking to bring my foundry to that and above. Thanks for the recommendation though!
Ill have to take a look at some firebrick

 

[kevin.decelles]

Standard refractory is the answer then....... My last batch, I ordered it out of the states (3 x 90lb bags) which cost 90 USD to ship to the border, then a drive across to 'mule' it home. That stuff is good for >3000 degrees. Local sources are hit/miss in Alberta. When it is booming, no-one wants to talk to you to sell you one or two bags. But now.... might be a different perspective. I've had some pretty ignorant encounters locally which is why I give my money elsewhere.

As a side note, I covered my ceramic wool WITH that refractory, then covered that with the ITC-100. Pretty tuff surface. I don't know how it would react to a torch flame at 20 PSI though.

 

[Tom O]

For the bottom of my furnace I started with clay that didn’t work out that great so I put some leveling sand and topped of with a kiln shelf plate. the furnace is propane / kaowool with the itc coating and I have cast alum and brass with it no problem.

 

[Bofobo]

I also have the kiln shelf as a foundry bottom, if you want away from refractory cement and wool you need kiln bricks preferably, I have a 20lb propane tank lined in wool with refractory sheet 1/8” to line and as mentioned a kiln shelf... I got it all at the local pottery supply store I found online except the tank. And for supporting crucible more pottery shelf items are ideal

 

[Oldarm]

Hello all, first post here.
Got some questions for you more experienced peeps.

I'm a student who's quite interesting in melting and casting metals. I started with the whole king of random bucket one with a simple steel foundry I made in shop class. Now I've moved onto my next foundry design which is a little more professional. Its a simple hexagonal steel bin thing I welded together with ceramic wool on the inside for insulation, and yes before you say anything, I've sealed the wool and I still always use a respirator with it. Currently I'm finding that the ceramic wool is slowly melting and degrading, and most importantly, I just pulled out the stuff lining the bottom of my foundry after it melted to my crucible :/ . I was wondering if you guys could suggest some kind of hard refractory to put at the bottom to place my crucible on. I've been looking at satanite. Put a bit at the bottom and some lining the ceramic wool to protect it a bit. And then seal all that with ITC 100.

Is this a good design? (Im using propane)
If not what is?
Also, where do you guys get your supplies. The only good place I can find to sell this stuff is charging like 40 dollars in shipping for 5$ of stuff. (I'm in the GTA Torontoish area)

Thank you for reading (and hopefully helping).

Hi, also in the Torontoish area, Brampton to be exact. What materials are you planning on melting? It has been suggested that you use regular firebricks for the base and crucible plinth. That is the best of ideas. Infill the joints with tamped down dry sand and point with fireclay.
For the furnace walls I would suggest using DIAMATACEOUS firebricks. These are very light bricks which can be bought as a standard sized brick or in various other shapes and sizes. Even if you need to shape the brick to suit the contour of the outer furnace shell, this can be done very easily with a hand saw or, using an old blade, on a bandsaw. A huge advantage with these bricks is that you are not expending lots of energy heating up a ton of regular firebricks bricks every time you are getting a melt on and there is minimal transfer of heat to the carcass of the furnace due to the excellent insulating properties of the material. (Think Kaowool) Also, no drying out time as with pourable refractory.
I don't see you melting steel or cast iron so no issues there with massive temperatures. Brass, aluminum and the zinc alloys will present no issues. If you are not planning on continuous melting but just one shot pours of say 5lbs to 30lbs let me know. There are very efficient ways of smelting, say, 20lbs of aluminum in 20 minutes for example.
John

 

[Tom O]

I also have the kiln shelf as a foundry bottom, if you want away from refractory cement and wool you need kiln bricks preferably, I have a 20lb propane tank lined in wool with refractory sheet 1/8” to line and as mentioned a kiln shelf... I got it all at the local pottery supply store I found online except the tank. And for supporting crucible more pottery shelf items are ideal

I used a beer keg for mine with a forced air blower for faster heats.