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Casting a Model Westinghouse-Type Twin Steam Engine in Iron

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vtsteam:
Thanks again, Ironman.  :beer:

Ah,slightly reducing probably explains why you have so little loss in your pours compared to mine.  :clap:

I take it there is no problem with a small amount of copper in the iron melt. I guess the wire probably mostly vaporizes anyway. I'll have to experiment with the wire types I have and see what works.

If you get a chance, could you measure the diameter of your alternator field wire? That would helpful as a starting point for finding similar copper wire.

I'm going to give the Westinghouse engine block another try when I get another core made up.

ironman:
The wire I use is 1.15 mm Dia. Small amounts of copper do not matter in a iron melt. I look forward to seeing you to recast the engine block.

vtsteam:
Great, thanks so much :beer: I'm glad you measured it as I imagined it was quite a bit finer. Now I have a good starting point. Here that would be 17 ga. AWG.

I'm re-thinking the corebox. The plaster of Paris version has a crack in it -- I can repair it, but I'm thinking now about fabricating or casting one in metal. Since I'm using a baked sand core for this engine, it would be convenient to bake the core in a corebox, or corebox half, unless that causes release/clean-out problems. Or I could  make a core plate for that, since I'm going traditional. Then the corebox could be wood, which is easy for me------- well, still thinking about it.

It's interesting to think about....making a corebox from the solid has pretty much the same shaping considerations as making a die, the alternative being molding it with some compound from a plug, eg. plaster, etc

vtsteam:
I repaired the plaster corebox and baked a new core in preparation for another go at the small Westighouse steam engine casting. This is really a test piece, rather than an engine I want to build at present. But it's an interesting challenge, and it helps me understand how to design a better engine pattern, core and corebox, and I can also try different types of scrap iron I have on it.

To me the ideal corebox for baked sand cores would be made of aluminum so you could not only mold it in the box, but bake it there as well. And the best aluminum corebox would be relatively thin around the core -- say 1/4 or 3/8 inches thick (6-9mm). That way it would heat up quickly, and also use the minimum amount of aluminum.

Plain Plaster of Paris is fairly resistant to heat, but is still rather delicate, and the temperature must be kept around 200F if the Plaster is to last for repeated use, when ideally you'd be able to bake at 350F. Also plaster coreboxes like the one below, poured into a containing box, are massive. That bulk plus the fact that plaster is an excellent insulator means extended bake times for the core.

I would think that an aluminum core box would bake a small core out like this one in about 15 minutes in a small toaster oven at 350F. The existing plaster box took about 45 minutes, and I still had to finish the ejected core for ten minutes at 350.

vtsteam:
After replacing the furnace lid with a new one built from scratch, I did a melt this morning. I think everything went right as far as I could tell, plenty of metal and it was hot enough. I melted 7 lbs even thought the casting only needed about 3. I useddisk brake rotor, and 11 grams of ferrosilicon was added. It took about a half hour to melt from a loaded cold crucible, and then another half hour to add more iron, slag the melt, add ferrosilicon and get it hot enough to pour.

Not sure why my earliest melts with this furnace this year were about half that time, but I'm starting to suspect the iron itself. I think the first iron I used was an easy melting variety, and the latest disk rotors are not. That might fit with disk rotor metal tending to chill easier, increased toughness and hardness. Maybe rotors are lower carbon. I dunno.

There was a fair amount of really thick chunky slag in this melt. Disk rotors in Vermont get a lot of salt corrosion --especially in the hollow ventilated part.

Anyway, here's the pour....nice and neat. The ingots, less so -- I need to level the base here better...

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