Hi all, I'm currently planning on making model detail parts (about a few inches by a few inches in size) that are not commercially available. I would "kitbash" these or make them from scratch out of styrene, but the problem is that I plan to make a few hundred of said pieces. I have come to the conclusion that I must make a "mold" for these pieces and "cast" them; the problem is that I've never done this, have no idea what should be done, and even what materials I would need to use. Can anyone offer any instructional advice or links to educational resources that would enable me to mass-manufacture these parts? Could I make them out of plastic, or would they have to be plaster? Etc., etc. Thanks for any help you can offer!
See if your local hobby shop still has a copy of the May issue of "Fine Scale Modeler" magazine, it has an decent article about casting resin parts. Nelson
Also try Micro-Mark Small tools. They offer a booklet which I believe has molding supplies and a How To Book
I have been doing a lot of resin casting using RTV molds. My biggest problem was having voids and air bubbles in both the mold and the cast parts. I finally broke down and invested in a paint pot that I use as a pressure chamber. I use it to both cure the RTV molds and cast parts in. At 70 PSI most all the bubbles vanish into microscopic blips. Some folks also use vacuum to de-air the RTV and resin but I have found that an unnecessary step.
For a few hundred, I'd try casting--and more than one at a time. Once you've made the master to your satisfaction, you can make a number of molds from RTV. I'd suggest getting one of the "beginners sets", either from a LHS or on-line, on resin casting. It's really fun!
I did some part casting and posted my results here. http://www.trainboard.com/cgi-bin/ultimatebb.cgi/ubb/get_topic/f/8/t/001337.html? You'll have to read down a ways. I had trouble with the first casting kit I purchased and if you keeping reading down you'll see what I ended up doing.
Very well done model and article both! While you are making a mold, and mixing the resin for the casting, do you smell any odor from the "rubber" mold or plastic of the casting? I became highly sensitized to the catalyst (polyisocyanate) used in both mixes. The vapors eventually coated the inside of my lungs, so it is pretty difficult to breathe through a "rubber balloon" now. Have you found a non-toxic pour-able plastic?
Here's something I just spotted on eBay.eBay item It looks very educational, non railroad specific. {I have not tried this product nor am I affiliated with the seller or producers of this item.}
