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Casting

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The basic necessities, a furnace, mold, some crucible tools and alot of time.

It's hard for me to believe now, looking back 5 years to this picture... What humble beginnings! Casting out in the dirt.

 

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Sand and Flasks

Green Sand: Not actually green....The term used for moulding sand that is not chemically bound. I use a very fine sharp silica sand and Bentonite mixed about 25% I find adding a touch of oil makes the sand bind better, yet remain "fluffier" before ramming. I add wood flour in the sand near the part on the drag side to keep it from buckling. Flasks: I have made several sizes of flasks for my various parts, all wood. The sides are 4" with a groove cut into the lower inside edge to help grip the sand to prevent drop outs. The ends have steel locating pins to ensure positive locating. I also have latches to prevent leaking.

PHOTO: Near the beginning our sand was a nice light brown, it turns black after time due to burning. I am ramming-up a side frame in this picture.

 

 

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Patterns

I made each pattern from scratch mostly from aluminum, some detail areas are formed from metal filler or epoxy.

PHOTO: Top Left- core mold for bolster , Top Right- core mold for side frame, Middle- side frame, Bottom Left- cross member, Bottom Left of Center- Bolster, Bottom Right of Center- brake shoe ring, with brake cylinder inset, Bottom right -transom member

 

 

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Sucesses and failures

Early on One of the biggest issues encountered was buckling where the sand would lift up near the part and make devistating blemishes. this occurs when the sand expands and forces itself into the cooling part. Wood flour was the cure for that, as the wood particles burn out it gives room for sand expansion to take place. The other major issue is shrink spots. Point where molten aluminum is drawn from as the rest of the part solidifies. I've found that in small parts it is well controlled with a carefully laid out sprue, runner and gate on larger parts by cutting the mass by using cores or recesses in the part.

PHOTO: A prepared mold before closing, you can see the Core that solved the shring spots. The core mold is seen in the pattern photo, a very intricate piece in itself.

 

 

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Like Christmas Morning

The best part is opening the mold after it has cooled! Everytime is like the first, it just never gets old. You find out if you sweat has been worth it. or if you have wasted the past 2 hours.

 PHOTO: The sweet reward after a long days work.