Been working on a new furnace. I figure my 8" bore Gingery-style charcoal furnace works great, but I've been using it for lost foam aluminum casting for coming up on 2 years and so it's about time I built something a little bigger. With proper refractory and insulation and a tangential tuyere, to give me a bit more versatility and allow me to play around with a burner...
I got a couple of 30 gallon steel drums which are about 18" diameter, so I have my outer shell.
I got 3 50-lb bags of Unicast 70 dense castable refractory rated at 3200F, so I have my refractory.
My 2600F rated ceramic blanket and insulating firebrick will have arrived at the pottery supply shop today, so I will soon have my insulation.
I decided to follow the example others have set and start by building a cart for the furnace to sit on and get rolled around on. I used 1" square tubing for the frame and an unfolded sheet metal oven drawer that I hung onto when my yard-oven finally went off to the dump with its friend the yard-fridge to build the platform. Since I don't have the equipment or the know how to fabricate it by welding, I had to use a combination of nuts and bolts and pop rivets and brackets. It doesn't have wheels or a handle yet, and the bit of extra metal protruding off one side needs to get trimmed off, but I'll get to that soon enough. Here's the cart so far, I think it will work out well; I built it longer than the furnace will need so that I have some extra room on it so I can wheel some of my other gear out into the back yard with it..
I also cut out some (3) legs for the furnace itself, and notched them so they can be welded flush to the sides of the barrel without the protruding rim of the bottom interfering. They will allow it to sit up above the cart so I can slide an ingot mold under the bottom drain in case of spills or attempts to direct melt larger scrap.
Also cut out most of the pieces for the lid lift/swivel mechanism, other than a pedal and lever.
From top to bottom:
- 1" pipe for the upright part that will be raised up when the pedal is depressed
- 1-1/4" pipe hinge for the lid. I probably won't use the 3" nipple in the pic, I have a long piece I will use for all the 1-1/4" stuff but it's not in the pic.
- 2" angle to connect the lid hinge to the lid via welding.
- upper flange, will be bolted to the 1" pipe so it will push the lid hinge and angle upwards when the pedal is worked.
- 2" angle to connect more 1-1/4" pipe to the furnace body to hold the 1" pipe steady.
- lower flange will be bolted to the cart. The 1" pipe will pass through it and a hole in the cart to rest on the lever the pedal will raise so it will lift with it.
A friend who is pretty interested in my hobby is getting in touch with his brother-in-law who owns a welding machine and will hopefully be interested in helping. If not, there's a guy just down the road who is pretty nice and has made a welded steel crucible for me before as well as the stand and grate for my 55 gallon wheel melter. Wish I could do it myself.
I have built a moya waste oil burner, but so far I have only tested it on propane (to do 2 aluminum melts in a ring of old house bricks) which will be used to preheat the furnace. Old pic, not quite complete as the propane line wasn't installed yet when it was taken, but it is fully built now. I have a bucket max shop vac for a blower, and I still have my hair dryer that I use in my charcoal furnace, which worked well when I tried burning propane.
Ack! Upside down pic...
Last but not least, I have some 14" wide duct tubing left over from making the shell of my charcoal furnace and a 12" sono tube to use as the forms for the castable hotface. Ie. it will have a 2" layer of ceramic fiber and 1" of castable surrounding. 12" bore. I plan to insulate the floor with the insulating firebrick underneath some castable for stability and the walls and lid with the ceramic blanket. I'm considering using one brick in the wall where the tuyere will pass through for a bit of extra stability there - a good idea or not?
I think that's about all for now, I'll be working on it whenever I get a chance and will try to update regularly. Comments and suggestions are welcome, ideally when they arrive in time to stop me from making some stupid mistake!