Other Foundry Components

Homemade Foundry - Crucible and Handling Tools

Crucible: Dan suggests having a steel crucible made for the furnace. My welding skills weren't up to par at the time, so I tried to get pricing from a couple local fabrication shops. I finally was able to get a response from one of them, who wanted to charge $100 to do the welds alone if I supplied materials! I started to look into a commercially made ceramic crucible, and found a local supplier in Aurora, Ontario: Canadian Thermix. They were very nice and helpful to work with, and I got a good deal on a bilge shaped, silicon carbide crucible with a capacity of 6 pounds of liquid aluminum (known in the industry as a #6BB). I paid about $95 CAD for it which I think is reasonable.

My Silicon Carbide #6BB crucible when it was new

Doug at Canadian Thermix explained to me the process of heating a crucible for the first time; it has to be done carefully. I heated it in my furnace on low power for about two hours, then cranked it to max and let the crucible cook for another hour or so. It seems to have worked, as the crucible hasn't failed yet. Since the initial firing the appearance of the crucible has been different. It is much shinier and after handling it, your hands get covered with graphite. It is also quite porous, especially around the top, which I'm not sure is normal.

The full crucible, ready to pour. (Click for a bigger view)

Handling Tools:

To buy commercial tongs and a shank for handling the crucible would cost several hundred dollars, so I opted to make them.

Tongs: I based my design off of tongs that you can purchase commercially. I'll post a drawing with dimensions eventually, but you should be able to figure it out from the pictures.

My tongs are built entirely from mild steel flat bar. The handle pieces are ¼" x 1", the bent bits are ¼" x ¾" and the parts that contact the crucible are 3/16" x 1". I purchased an "elliptical ring roller" from Princess Auto to do the rounded parts, which worked quite nicely to do the evenly curved parts that contact the crucible. I welded the pieces together with my little MIG welder, and used a 5/16" bolt for the hinge.

The tongs turned out very nicely. They feel much more solid than they probably need to be, and they fit the crucible perfectly. I can confidently say that I think they're nicer than the commercial ones I looked at, and cost a fraction of the price to build.

Shank: The shank was a bit more difficult to make than the tongs, as the crucible sits on "pads" within the support ring. I used a piece of gas pipe for the handle, rolled flat bar for the ring, and smaller pieces of flat bar welded inside the ring to support the crucible. I had to machine an angle on these pads using my mill so that they would fit the shape of the crucible, which was tricky. The locking mechanism was also hard to come up with and I'm not fully happy with it. Still, the shank hasn't let me down yet and was really cheap to make.

The shank right after a pour (Click for larger image)

Close-up on the shank locking mechanism (Click for larger image)

You get a good shot of the tools in my first video.

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