I'd like to cast some scale engines for a boat - I have all the pieces made for the master to take a mould from....
The main engine block etc seems fairly easy to make a casting from, but what I'm confused with are the smaller items... Tiny little bits like carburettors, pipework etc. So for example, if I have a peice of piping which is less than 1/8" diameter, with multiple bends in it, and about 2"-3" long, how would I go about making a suitable mould and casting that?
Regards
Eddy
if you use a good quality resin it is do-able ! i would recommend using clear silicon so you can see the original embedded in the rubber,
so take you original and mount ready for encapsulation in silicon,i use styrene rod for my mounts.... the mount will also become you fill point, so ideally mount from one end or from a point from which any surplus material or flash can be easily removed, make a set of walls or shuttering that surrounds the original, this will become the container for you to pour your silicon into, so no gaps anywhere !
when you are happy mix your silicon ( transparent stuff ideally with a small part ) and let it cure, also being transparent you can see if any air has been trapped in the silicon - if so aggitiate gently or vibrate until all airbubbles rise to the surface ( or if you have access to a vacuum chamber put it in and under vacuum this forces air bubbles to the surface)
once the silicon is cured carefully cut through the silicon with a sharp scalpel, so as to cut the mould in half, ( i always cut with a wavy cut line so the mould will only ever go back in one position ,this way guarentees correct location of the two mould halves too.
once the mould is cut in half remove the original from the silicon and remove the mount which now becomes the fill point .... then replace the 2 halves of mould together and use adhesive tape to join the silicon and to seal the cut, get the two mould sections tightly together and the tape holds them in place.... leave the fill point untaped, then mix your casting resin then pour or inject with a syringe the resin into the fill point, the resin will then fill the void left by the master,check there are no bubbles in your casting resin, if so gently aggitate to remove air bubble - once cured remove the tape and split the mould, remove the resin part, clean off any flash and cut off any surplus resin from the fill point and hey presto you have a resin copy of your original...i have cast tiny details before for an N scale model railway the details were 3 mm tall and 4 mm long, no problem doing these....good luck and have fun !
