I think it was Jonathan in one of the threads posted a link to a guy that had built a gantry mill and it all seemed solid to say the least(that's a compliment from an x shipyard fitter) then for some reason he went and painted it pink.can you use a slow set hardner to try and reduce the exotherm ? is there any way you could surround your mold in a water bath, when we installed D5 Launch tubes they were back filled with water and the water was circulated with a pump, all in an attempt to reduce shrinkage and seperation of the two component parts(our tubes were better than any of the yank's)
What sort of size were you thinking of.