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Resin Casting for your own good?


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I have been getting back into the hobby slowly. I've looked around at the price of resin items, I think to myself when it comes to buy resin items I could almost make way with doing it myself cheaper? Now, I won't be casting for someone else, So would I benefit enough from doing it myself?

I build alot of the same models, C1500s, Dodge Ram VTS, 99 Mustang Cobra to name a few. If I could get a good master down, I'd like to resin cast a few of the things I've built for my builds. Custom shaved beds, tailgates, Cowl hoods, Seats and Wheels as well as other custom parts I've build so I can use them in future builds. I have began a 97 F-150 Crew Cab cab, Dodge Ram VTS Crew Cab, If I were to get it to where I am happy with it, I'd really like to cast it so I wont have to keep rebuilding the same things over and over.

I also was curious, When resin casting how hard is it to make a mold and whats best to use for making one? I looked on youtube for a couple hours watching different methods of casting and how people do it.

Any help from someone who does this, would be appreciated!

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For your own personal models you can make copies of whatever you want. Most molds are not that hard to make. The best mold-making material is room-temperature-vulcanizing (RTV) silicone rubber. It is available in several different flavors; the easiest ones to start with are the 1:1 mix ratio rubbers, like Oomoo from Smooth-On. That rubber is very easy to use, but the trade-off is it is physically weak and does not stretch well or yield many castings.

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Casting is kind of like taping a show off of TV. You can do it for your own use and no one cares, but if you copy someone else's work to sell, then people are going to start noticing. The Hobby Lobbys around here have the Aluminite casting products for $29, and you can use the 40% online coupon and get them for around $18. There isn't enough to do a body in just one kit, but you can do a lot of engine blocks and other small parts.

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I just got a good deal on a sale at micro mark on resin and silicone as a package. I just cast some Desert Dog tires they came out pretty good. I have cast an entire body and it works out well but the cost does add up. You can see why a good resin caster has to charge so much for his product. post-1299-0-36136400-1365357997_thumb.jp Also remember some resins have limited shelf life, so if you can have a bunch of molds ready to cast you can avoid wasting resin.

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Both silicone and resin have a limited shelf life, so whenever aI get in th emood to do any of that, I try to put together enough parts to use up all the silicone. Then I buy it and make my molds all at the same time. Then I cast parts until I end use up the resin. That way I can add them to my parts box. Once I am through casting for a while, I put the molds into a zip lock to keep them clean.To cut expenses, if you have any unusable molds, either ones that didn't come out right or ones that have been used up, you can chop them up, and drop them in as you pour the new mold. The finer you chop them up the better.They will take up space and you will end up using less new silicone. I have done this several times and have never had a problem with it.

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Here are some inexpensive ways to get into casting parts. If there is interest, I'll post photos. I've used these methods for slush molding an entire body as well as small parts.
Permatex Red High Temp RTV Silicone Gasket Maker
Permatex results in a fairly strong, flexible mold and will take fine detail. If used by itself, this must be applied to the master in thin coats. Can be mixed with flour (my preference), sawdust or Durham's Water Putty to speed curing and allow thicker coats. Flour or Durham's (a relatively strong plaster) shouldn't excede about 1/20th in volume or the mixture may not harden properly. I mix on a hard surface, repeatedly spreading the flour/RTV mix as thin as possible. This seems to speed curing (it may absorb water when spread thin). I don't go over about 1/4 inch thickness with each coat. Sawdust should be screened down to near-dust size particles for best detail. Coarser sawdust can be used for outer coats for strength. The Permatex will cure regardless of the added amount of sawdust, but too much may weaken the final mold. I've used a 1-to-1 mix without problem. With either additive, the Permatex still likes ambient moisture to harden. I use a plastic box on a plastic surface with damp paper towels under the mold. I've read that RTV in general will harden faster with heat, which makes sense. If using urethane casting resin, mold release agent may not be required, but may help extend the life of the mold if it has fine projections. It stretches well, but doesn't seem to compress.
Urethane Casting Resin
I've only tried three types: Alumilite, and MicroMark CR-300 and CR-600. I strongly prefer CR-300. It has a short (a few minutes, more resin means faster hardening) but workable pot life, doesn't smell as much, takes fine detail and is very easy to carve and work when fully cured. It is similar to styrene, i.e., not very brittle. I use thin fabric as a way to make thin castings stronger, like using fiberglass cloth to lay up a surf board. The CR-300 soaks in and through, so a trimmed sheet can be positioned in the mold before pouring the resin. Work out any air under the sheet as much as possible.
Casting Durham's
Durham's Rock Hard Water Putty can be using for casting larger simple objects, too. I have mixed in waterbase acrylic paint slightly diluted with water to add strength and workability. Once in the mold, tap or vibrate the mold. This will liquefy the Durham's to help fill the details of the mold, but doesn't seem to cause any problems with hardening. Hardening will take overnight. This is a very cheap material.
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