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+--- Thread: Looking for help on casting small parts (/showthread.php?tid=8354)
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Re: Looking for help on casting small parts - dave1905 - 04-12-2017
The orbital sander trick works for RTV molds.
200 degr seems a bit high on a curing temp, probably anything over 125-150 would probably work. The resin heats up as it cures and that heat helps it cure and harden. Thin sections don't generate a lot of heat and so need help to fully cure in some cases. When I cast car shells I put the mold with the casting still in it in a 125=150 degree environment (under a 150 W flood light). That way the thin shell sections fully cure before I take them out of the mold.
Re: Looking for help on casting small parts - twilight - 04-12-2017
Yeah, Dave your right about the temperature. Allumilite recommends a lower temp too at a longer duration. My toaster oven doesn't go below 200 so I shorten the time and kept an eye on them. I'll try the 150 w floodlight next time. I think I have one in the garage.
Thx,
Mark
Re: Looking for help on casting small parts - twilight - 04-19-2017
Here's a shot of the new castings on a C&BT shops EBT hopper. Latches are only primed. Took awhile to get to this point.
![[Image: IMG_5201_zpsam51gxtf.jpg]](http://s1081.photobucket.com/user/bowser0227/media/IMG_5201_zpsam51gxtf.jpg.html)
Re: Looking for help on casting small parts - Eccentric-Crank - 05-01-2017
I bought silicone mould material from a local supplier to the movie industry.
The instructions say to place the mixed stuff in a vacuum chamber to get rid of bubbles.
Same goes for the resin, let the air pressure back in before it has a chance to harden.
Slow curing resin or epoxy will have more time for the bubbles to float and pop.
An old refrigerator compressor makes a good vacuum pump.
I use a heavy glass cake dome for the chamber on a piece of scrap countertop drilled for the vacuum connection.
I use cheap RTV in a tube to seal the dome and place it on the flat surface with wax paper,
so it doesn't stick to the counter top material while it cures.
Dan M.