What a miserable winter this has been. The furnace is buried under snow (all wrapped up in plastic though) and I’m starting to itch to try a little forging this spring. When does the snow stop coming??
It’s been a while since I’ve posted… there’s just been too much going on. Before winter sets in though, I’d probably better get a little 3000 degree furnace cement to finish dressing up the interior and smooth things out, then coat with ITC-100.
Well, it’s now time to finally put the burner in the furnace and bring this forge up to temp to do a nice burn-out prior to coating with the ITC-100 Infrared Reflector. As a result, it’s not going to get as hot and be as efficient as it WILL be later, but I need to get all of the burnout done before sealing it. This gives me a chance to see what it can do.
This is the furnace after a few minutes to get up to heat. The object in the center is a steel can that I was melting aluminum in… a nice hot orange. The rod to the left of that was a graphite rod that I snapped and it fell ito the furnace. Hot hot hot.
Call me a late-comer to the party, but I have a young child and getting to the movies isn’t easy sometimes, even for Christopher Nolan! Still, I finally managed to get to see the movie last weekend and wasn’t disappointed at all.
On the surface, everything seems to be rather straight-forward if thought-provoking. Cobb and friends need to plant an idea in Fischer’s noggin such that he breaks up his mega-conglomorate for the good of the world. In return, his benefactor Mr. Saito will miraculously make all of his issues vanish. We later learn that the issue is a murder charge against his ex-wife, Mal.
Yadda yadda yadda, action ensues, multiple levels of dream misdirection, and ultimately success as he’s re-united with his kids. Right? Right?? Did the top fall or not?
Ultimately, if you get caught up in that question I think that you’ve taken the red herring bait. Just as Inception depicts Dreams-within-Dreams, Inception-the-movie serves up multiple levels of what’s actually happening.
The forge should be functional now, I’m just lining up the dots before my first full burnout which I’m going to combine with an alluminum melt/casting.
While I’m finishing getting that all around, here’s a picture of an anvil I picked up recently. Not in the best of shape, but a decent deal for a 161 lb Fisher. I may go some grinding on the edges to clean it up and make it usable, or just use a hardy tool (more annoying.)
As mentioned in Casting the Base, I added in the Inswool blanket around the refractory shell. At the very bottom, there’s not enough room for the full 1″ wrap, just .5″. Then 1″, then 2″ at the top. My last-minute decision to widen the crucible chamber for big pours has reduced total insulation value. Still, there’s a lot of insulating refractory even with NO extra inswool in the bottom couple of inches (about 1.5″ of highly insulated refractory + 1″ of inswool for the outer liner), so I’m ok, I’m sure.
Before doing the base I had to wrap up the lid. My initial plan was to weld an iron pipe cap to a piece of electrical conduit that would be an arm to hold the cap (with a hole) in place. I was having one heck of a time trying to get the cap welded to the conduit. Maybe it was just a thermal mass issue and if I’d held the heat longer I’d eventually have gotten the cap to sufficient heat… I eventually gave up as the arm kept getting dislodged, bad semi-welds happening, etc.
Instead, I mounted the lid and created a “basket” from welding rod. It’s not pretty, but should help keep the arm in place. Whether my whole assembly is strong enough to support the cap, or whether I’ll need some additional shoring up I’m not sure at this point. Back to this issue later…
So, I then removed the cap and baked it to sturdy up the paint and drive off water and start burning out some volatiles in the refractory. I did a nice slow ramp (at least it seemed slow) from 250 to 550 F. I held at 250 for about an hour then went up about 50 F every 20 minutes in the oven. The “real” burnout will happen with the burner up to full temp, but at least there won’t be any significant water left to crack it and the paint is now toughened.
So, onto the base…
Before doing the casting, there was a little more work to do to prepare the cap. I welded an electrical conduit pivot on the handle and built up the forge shelf rest to improve strength and improve visual appeal. The pivot will fit into a sleeve attached to the bottom to allow the cap to slide up and down, and swing out-of-the-way.
To keep the refractory from sliding out of the cap, sheet metal screws go through the metal ring and into the interior. Additional support screws are located at various points along the surface. The refractory will surround the screws and the weight will be distributed to multiple points to stay in place and keep from pulling out.
2000 degree F paint was added to the area around the ports.
Before wrapping up the lid, I figured it’d be a good idea to get the mechanics of the lid wrapped up. Since this is a Foundry Furnace, a crucible will be inserted into the body filled with metal to be melted. To trap heat inside, you need an insulated cap to the furnace. So, it becomes obvious that you need a means to move the cap out-of-the-way when you need to insert or remove the crucible.
The simplest method of doing this is to install a hinge on one side and lift it. This has its down sides though. If the lid will tilt up, then it precludes us from using the top for other purposes without moving things. Ideally, I want to be able to use the top as a “burn-out oven” to vaporize wax in investment flasks or to pre-heat molds so that I am less likely to have an incomplete casting. Keeping the lid horizontal is preferable if at all possible.