How to Save Money When Buying silicone casting service

Casting

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Ken,

I've also used Aluilite. The resin seems to brittle to me. When Railflyer decided to call it quits he thanked some of his suppliers. I was interested in what he used for his models since I had bought one. The castings were very nice in detail and cross section. One of his suppliers was Smooth-On®. I ordered their Pourable Silicone Starter Kit.

I've only used the resin to make a roof for one of my critters I'm building. I'm very satisfied with the resin. I can't speak for the rubber part since I haven't used it. I based my purchase on the fact that a model railroad manufacturer used this product to turn out a very nice resin kits.

Here's the link to where you can purchase it, including other material for resin castings.

http://www.smooth-on.com/Getting-Started-Po/c4_/index.html?catdepth=1

It may not be in your budget at $52 for the kit but. I think that if you're looking for quality material you are going to have to pay the price. From what you stated in your project of making many copies it might well worth it in the long run since the molds would hold up better for the number of castings you want to do.

Oh almost forgot, Railflyer also has a second vendor for molds and resin.  http://www.reynoldsam.com/

They may both be higher in price than you want to pay for, but they are of higher quality than the Alumilte casting material in my opinion.

Bernd

Alumilite vs. Smooth-On

I have used both Alumilite and Smooth-On products. 

For someone who is new to moldmaking I would recommend the Alumilite kit for practice because of the price. For the experienced moldmaker, Smooth-On wins hands down. 

Alumilite RTV is not as flexible as the Smooth-On product I use and therefore makes the part(s) harder to demold. Additionally the Alumilite resin was of a lower quality than what I was able to source locally through TAP Plastics at about the same price.

I use the Smooth-On "OOMOO 30" with great success for both resin and hydrocal casting. Many other compounds are available at various prices but there are trade-offs for the lower priced products.

Bernd is absolutely right: if you want quality materials you have to pay the price.

As a side note, I live on the West Coast. When I called Smooth-On to order product they directed me to Reynolds so that I could save money on shipping. Great customer service from both companies.

-Jonathan

Vacuum Chambers

Back when I was using Alumilite casting rubber and resin I made myself a vacuum chamber using a compressor from a refrigerator, 3 Pyrex glass bowls and a piece of 12" X 12" MDF board covered with counter top laminate, a piece of 1/4" brass pipe epoxied into a slot rounted into the MDF board. A hole was drilled in the center that connects to the pipe.

The compressor. Yes it does do vacuum to. You can use it for either a compressor or a vacuum pump. Remember that it's a closed system on the fridge. So on one side it compresses the refrigerant. The refrigerant expands cooling your fridge and on the other side it sucks the refrigerant back into the compressor to start the cycle all over again. If you use one of these be careful not to dump out the oil that is used for a lubricant. If you use it for a compressor make sure you dump the oil out or other wise you'll get oil mixed in with what ever fluid your spraying. Yes it will eventually destroy the pump, but mine was free and I have several more to use, all free. I got mine at a transfer station from a refrigerator that had the refrigerant taken out.

The laminate, MDF board and 1/4" brass pipe.

The three Pyrex bowls with a ring of silicone sealant on them.

The whole rig ready to de-air a rubber mold or resin casting.

I know you can buy vacuum chambers but I think your going to pay a high price for such an item. At least I can customize my chamber for the size I need for the job I'm doing instead of being tied to a size a manufacturer wants to sell me.

Contact us to discuss your requirements of silicone casting service. Our experienced sales team can help you identify the options that best suit your needs.

BTW this was for small castings. I made masters for On30 log cars and did some castings. Although I really didn't need a vacuum chamber it did help with the resin casting as Aluilite resin wasn't always air bubble free.

Making your own castings is fun. Try it sometime.

Bernd

Vacuum and pressure

I have read that you use a vacuum chamber for RTV (to remove air bubbles from the RTV before you pour it in the mold) and then use a pressure tank when casting (to compress the bubbles and voids). 

Using a vacuum when casting only works if there is a very clear route to the surface for the bubbles.  If its a complicated mold with undercuts, using vacuum when casting will result in bigger bubbles and voids.

I don't have a vacuum set up, but do use a pressure tank (a 5 gal paint pot) that is charged to 40 psi when casting.  That is enough to compress bubbles to pinhead size.  Epoxy castings use even higher pressures because its thicker resin.

Vacuum & Pressure

I made quite a mess the first time I started to learn about casting. I haven't used the vacuum rig but once or twice and haven't done any at all since I did the casting in the pictures I've posted. I found the rubber hardly had any bubbles. I was getting bubbles in the resin. The first time I used the vacuum chamber to de-gas the resin I had a big mess. Didn't realize it would boil like it did. The whole thing hardened before I settled back down.

I talked to a friend that I was having trouble with bubbles in the resin. He told me to cast under pressure. I tried that and I found that the resin was more brittle than if not cast under pressure. I made a chamber out of some PVC pipe that had a rating of 80PSI and used 40PSI as the casting pressure.

It was at this point I stopped experimenting with Aluilite. That was quite a few years ago. Since Railflyer had stopped his operations and gave thanks to his suppliers I discovered he used one of several suppliers for casting material. So I'm trying Smooth on.

I'm hoping to get back to doing some resin castings through the winter months when I'll finally have a little more time to pursue casting resin. My recent casting of the critter roof I did, I'm finding that I may not need a vacuum chamber at all. The resin is very water like and if mixed carefully won't have any bubbles in it.

It seems like all resins have a shelf life and need to be used before that runs out. I found the same true for Alumilite resins. I had to through several bottles out.

Bernd