The Shop > Metal Stuff
Oil fired crucible furnace
NeoTech:
Seems like you have solved that little issue.. =)
FYI, you can break down a V8 motor block thats is already cracked by heating the cylinders and then take a sledgehammer to it... =)
In the winter around here anyway i imagine i could freeze crack the whole thing.. (started some experimentations of acuiring cast iron from engine blocks.)
vtsteam:
Neo, don't know yet. If it eats up a $75 crucible, then it isn't practical -- we'll see. First melt with the new crucible will be without flux and with thick metal to take it easy.
Watch out for flying metal when breaking up cast -- especially the hot stuff. I've had some fun encounters in the past. Face protection is a good idea. But yeah cold probably will make it easier -- you and I probably have similar winters. I have to work outdoors though, and I imagine some of that cast will get lost in the snow, only to reappear in the spring!
Today it rained so I did a little cold forging of the lift out tongs to fit them carefully to the new crucible. Then I rolled a steel strap and welded on some handles for a hand shank. This is the closing type rather than the ring shank I made last time. I've had two instances where the crucible slipped in the ring shank when pouring, and it's no fun!
If you think about the geometry of a tapered crucible you will realize that this is a possibility when a crucible is even tilted to horizontal. It may not slip out of the ring, but it can suddenly alter its position in the ring with a consequent redirection of the metal. Even the best fitting ring will soon be pretty approximate as a crucible ages and shows slag spills, etc.
Anyway, I saw a clamping ring type shank in Colin Peck's book, so I used that principle here, though with my usual favored re-bar, and a bent down end.
ironman:
Tom
A riser is always is put in the center/middle of a casting so it feeds better. when a thick section is in a corner and the rest of the casting is thinner then the riser has to be located there. Some castings may require many risers. Some cast irons don't need any risers because as the iron is freezing graphite comes out of the liquid and expands offsetting shrinkage.
tom osselton:
Yes I know what you mean I was just pointing out what I saw in the pic how the two streams would meet and would travel in a circular patern. It is all interesting and will give it a go soon with aluminum to start. I have a blower and beer keg I'm working on and went with the fiber insulation because that would be the best choice in our winters I think the others probably would crack upon heating, or I can use the kiln in the basement for some al.
vtsteam:
I couldn't put a riser on top in the center because of the cored channel down the middle. But the riser works as it is presently located because there have been no shrink depressions since I started using it -- about 5 castings ago.
On the other hand, maybe the riser could be used to trap slag inclusions if it were in the center on top. Maybe they would float up into it. Unfortunately the channel is there and a riser would defeat the whole purpose of coring it.
Thinking about this, it might be possible if I made a new pattern, with the channel on the bottom instead of the top. (Yes there is a top and a bottom because of the draft.) Then the flat surface would be on top, and the channel on the bottom. A riser could then be located on top.
That might work -- maybe I'll try it.
But it is side stepping the issue of "where is the slag coming from in the first place". I might want to solve that first.
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