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Casting a Model Westinghouse-Type Twin Steam Engine in Iron

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vtsteam:
Hi Tom, the core was coated with plumbago (graphite), per Ironman's practice, and the facing sand had coal dust in it like his @ 4%.

It will clean up nicely if it anneals -- there's a generous machining allowance, particularly in the upper and lower flanges, and the bores are well undersized. There are no casting flaws apparent at all.

vtsteam:
Annealing worked. I simply put the casting back in my oil furnace, lit it up for a couple minutes until the casting was glowing a dull red, shut the furnace down, covered the exhaust port with a brick, and plugged the burner blast opening. Four hours later, I opened it up and took out the casting, which was still too hot to hold.

It filed easily, and the hacksaw, which skated before, now had no problem biting into the iron.

tom osselton:
She’s a beaut! What size crucible did you use? I’ve bought a extra #6 clay graphite for when I give it a shot but am thinking I’ll get a larger one later on. Now to find some Ferosilicon I’m pretty sure I saw some in Dads chemical collection otherwise ebay.

vtsteam:
Hey Tom, I've only used a #6 and not run into anything yet that I couldn't cast, including a 7" chuck backing plate. 10 lbs is no problem, and technically it should hold 20 to the brim, but that would be nuts as far as I'm concerned.

I think 12 lbs is about the limit I'm comfortable with. To put it in perspective, this casting weighs 2 pounds 2 oz. If you multiply by three for sprue, riser, losses, and some extra insurance to pour in ingots if everything goes well, that gives you 6.6 lbs. I melted 7, and had a fair amount in ingots. I haven't felt the need for a larger crucible.

However one advantage I can imagine with a bigger crucible is that for smaller melts, they wouldn't require adding more cold metal during the melt, because you could pack a full charge in it to start with. This would probably cut the time to melt by 30% -- judging by my last melt. -- and fuel, too. I was thinking about that very possibility.

Too bad an A8 costs proportionately much more than an A6 or A10. Must not be a common size....but it would be quite a convenient one for me.

As far as ferrosilicon goes -- I'm tempted some time to try a session without it, and then annealing the casting to see if that works. Ferrosilicon can't add more carbon, so it mainly must control crystallization on cooling. If you could get a similar result by annealing, that would be a boon.

I've also been thinking that the time to anneal, would be for a prior session's castings, placed in the furnace after the present one has been poured, and the furnace shut down -- they stay hot for quite a while after. No fuel needed, that way.

tom osselton:
That’s nice to know about the #6 crucible I have my dads kiln in the basement so annealing isn’t a problem for me. I’ll have to dig out my furnace from the shed mind you first I’ll have to cut the grass and see if the quads battery charges. Patterns won’t be a problem I have dads in the basement for his steam engine.

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