The Shop > Metal Stuff
Foundry Furnace for the Tiny Shop
vtsteam:
Second pour, with the form in place:
vtsteam:
Again I waited until the plaster started to feel firm. And then made the third pour. I'd done that before placing the Sonotube, too. Otherwise it would have embedded into the bottom, and been hard to remove.
vtsteam:
Lasxt pour. This time I added extra sand to make it a bit firmer so it wouldn't overflow the lip of the shell. I wanted to build the height up a small amount towards the cardboard form. That can be abraded back down to fit the lid -- but if the top is left with hollows, then it will leak rather than forcing the exhaust through the flue hole. A slightly thickened mixture allows that little bit of slope from the tube down to the shell edge, without runoff.
vtsteam:
Letting it cure for about an hour, I stripped out the cardboard form by collapsing the seam edge inwards.
It probably only took 2 hours total to renew the lining, and the cost was $16 worth of plaster of Paris -- the sand water and Sonotube, were already on hand.
I didn't have time to do the lid -- have to leave something for tomorrow..... :dremel:
awemawson:
Great work Steve, and also great to see you back doing things :thumbup:
I'm amazed that the P.O.P. lining stands up to iron temperatures even with the addition of the sand. When I was doing lost wax casting it was OK for aluminium but brass, bronze and copper needed a special high temperature version. For iron I used a hybrid of lost wax to form the cavity, and sodium silicate for the bond with dry silver sand - worked pretty well.
I'm no chemist, but as I understand it, the high temperatures decompose the P.O.P. by reversing the hydration reaction. :med:
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