Quote from Robert Howle on August 15, 2013, 12:21
Weight of model x 1.1 x S.G. of metal to be used = metal weight estimate
Quote from afholderman on August 15, 2013, 13:30
Quote from Robert Howle on August 15, 2013, 12:21
Weight of model x 1.1 x S.G. of metal to be used = metal weight estimate
I don't believe this formula is correct. The weight of the model in cured resin already factors in the specific gravity of 1.1. By multiplying it a second time you are increasing the effect of specific gravity. That is why I divided by 1.1, to get back to an amount equal to the specific gravity of modeling wax. This is because if you have identical models one in wax and one in cured resin the resin one will weigh heavier due to being more dense, as indicated by the higher specific gravity. So if you were to then multiple the already heavier model's weight by 1.1 you are increasing the gap between a wax estimate and a resin estimate, not reducing it.
Quote from akgold on August 15, 2013, 20:25
Weigh your casting model with the sprue and button on it then refigure your weight ratio.
That will give you a multiplier that determines the total metal needed to cast.
I use 15 times the wax weight of all items to be cast in 14k.
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