The Shop > Metal Stuff
Casting a Model Westinghouse-Type Twin Steam Engine in Iron
vtsteam:
Tom, what kind of steam engine? How big? Details, man!
Tom have a look at this video by Ironman using an A6 crucible -- he fills that thing to near the brim, 6.6 kg (14.6 lbs), and look how many castings he pours!
vtsteam:
Well the Westinghouse Twin casting has some hard spots, discovered after chewing up a couple mills. Very disappointing. I blame the disk rotor metal. Maybe different rotors have different compositions, but the one I used for this engine was tough to cast with -- took a very long time to melt, and was chilled even with .35% ferrosilicon. A subsequent trial melt of radiator metal took half the time, and produced nice gray iron with the same amount of ferrosilicon.
I should factor in, though, that the Westinghouse engine casting is pretty thin. Maybe the rotor metal would have worked better for a thick casting. Though going by the ingot, that was completely white (I think, now -- the fact that it looked silvery didn't mean anything). So I might have needed more ferrosilicon even for pouring a thick casting with it.
I've got another half dozen rotors -- from mixed vehicles, so I'm not sure if they will all behave the same. I'm wondering if I mix half radiator metal in with half rotor metal if it will get something with reasonable melt times and better softer iron.
As for the Westinghouse casting -- probably the best for that job would be straight radiator iron -- since that scrap is in thin castings to begin with, that might be a good match. But I'm a little tired of making cores, etc at this point, so it may be a few weeks before I attempt it a fourth time.
ps... After praising the A6 above, I actually went ahead and ordered an A10. I want to cast a faceplate for my new lathe, and that's going to take nearly 20 lbs of scrap iron. I skipped an A8, because it was only 10% cheaper than the A10 but substantially less capacity.
vtsteam:
Reboot on the third Westinghouse Twin casting:
I didn't have enough time before predicted thunderstorms today to do a full iron melt, so I thought I'd try annealing that last casting one more time. I was thinking maybe I didn't get it hot enough -- dull red, so this time I went for cherry red, and really let it have the full furnace blast. I also put a sprue and an ingot in there from that melt as test pieces -- to see if they changed.
When red hot, this time, I plunged them into a bucket of wood ashes for slow cooling.
This evening I'm really encouraged tio report that the ingot definitely went to gray iron, and the engine seems like it may have done the same. We'll know for sure once I get it on the milling machine. But I'm hopeful! :dremel:
RussellT:
You have me wondering whether it might be possible to anneal some sash window weights. I have tried machining them previously and found they were very hard.
Russell
vtsteam:
I'd definitely give it a try Russell! :dremel:
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