cast plastic molding?

Question

How do you make a copy or another mold of a plastic screen off a grille on a farmall 140 tractor. What kind of tools. what is the precendure.

Answer 1

Well that depends on what you plan to do with the mold when you have it. Plaster casting would probably be your best bet. you could also sand cast it, wax cast it, and a couple of other ways.

For all the ways that I know of, you need a good part to cast from. You can also do partial castings to create just a piece to make repairs with. If you need more than a few, have a professionaly made metal mold made. You cannot do those at home.

For a plaster mold, find or build some kind of container a bit larger than the part you are going to make a cast of. make sure it is high enough to make a good thick mold. pour the mixed plaster of paris in the container, and level it out. push the part into it until it is clos to coming over the back of the part, but not quite. (OH coat the part with a non-stick spray like PAM first) let this set up. now if you take the part out, you have a one sided mold. to make the other side, leave the part in the first mold. spray the entire thing with the nonstick, and you might want to work in som paper or cloth, but not too close to the part itself if you need an accurate casting. fill the container up with more plaster. when it is thouroughly set up, take the whole thing out of the container.you should now have a two piece mold. hopefully it came apart where you sprayed it with the non-stick stuff. Now, to fill the mold with anything, you will need to take some kind of tool like a gouge or maybe a dremel, and cut in channels so that all places can fill with I asume what will be plastic. don't forget air channels to let the air out as the liquid plastic comes in.

Another way, is to do similarly, but with liquid latex dipped on either side of the part first. That gives a more accurate mold.