Silicone Molding Compound

[FLtenwheeler]

Hi All

What is a good silicone rubber to use when making copies of plastic rapid prototype masters?

I see room temperature and others that need heat. Some with 0% shrink others with 1% to 2%.

Thanks

Tim

[RONALD]

I have used the first one #82083 shown on this list with good results.

http://www.micromark.com/SearchResult.a ... old+rubber

[steamin10]

AT most art supply houses, you can get setting vinyl molding compound. It comes in a bucket, is white until heated, and turns clear when heated to set temperature, where the vinyl links up and changes chemically. (Vinyl molding compound) You then pour it around your master, and when cool, slice it with a razor and pull your positive. The material is the same as they make fish lures and sex toys out of, and is fairly stiff. Once made it has a long shelf life, (keep it free from dust and dirt ina plastic baggy) and can be used until a mistake destroys or rips it. It can then be REMELTED, repoured and used again. I use a Chicken fryer for the countertop, from the 2nd hand shop for mine, as it takes some temperature to get the heat up. A crock pot wont work, way too slow and cool, but is what I use for my brown waxes for plaster based molds. Between the two, I can build and make just about anything with fine detail, in a lost wax process.

Sand molding is still the easiest and cheapest. But the ability to make intricate parts with lost wax, can really be a bonus.

It is not silicone, but the bonus is the ability to reuse it. It is told to me that various plastic compounds for making parts are compatible with a wide range of end uses for this vinyl material. Others, like the silcone that is sugested, cannot be repaired if torn during process, so care with parting wax/silicone/ PAM spray, must be used. Some things work better than others, this is just my cheap suggestion.

[jcfx]

Most rapid prototype plastics don't like heat, so any silicone that requires heat to cure is out of the running
Room temp cure ( RTV) is the way to go, the only considerations to take into account are whether or not your
pattern will cause inhibition, and if it's porous.

There are two types of silicone RTV's, Condensation and Addition, the former is
a tin based, the latter is platinum based cure, Addition ( Platinum ) cure silicones will be inhibited by sulfur
based compounds and amines ( badly mixed epoxy as an example ) as well as the occasional dirty look ( i've had it happen ).
They also have the least amount of shrinkage.

If you can take the shrinkage Condensation ( tin ) silicones are probably your best bet, they're a little cheaper
than the Addition and cure up against anything even sulfur bearing clays.

I've only had experience with 3dsystems rapid prototyping 3d printers so I don't know what all these other
printers final product is like, it's important that the output is solid with no porosity, silicone will flow into
a lot detail and any porosity on your pattern the silicone will physically lock on your pattern.

[FLtenwheeler]

Hi

Thanks for the replies.

Tim

[FLtenwheeler]

I have used the first one #82083 shown on this list with good results.

http://www.micromark.com/SearchResult.a ... old+rubber

I contacted MicroMark for the specs.

It is a tin cure silicone.
Shore A hardness: 35
Negligible shrinkage


Tim

[jkimberln]

I would use Castaldo LTV. It is a vulcanizing rubber. Although it is heat cured, the heat is less than the 3d plastic output from my printrbot. That is, the heat required isn't enough to deform ABS.

JerryK

[SteveM]

Not sure if this would work, but here's some molding stuff used in the food industry:

http://www.makeyourownmolds.com/silicone-plastique

You could make wheel patterns in chocolate!

Steve

[FLtenwheeler]

I am looking at some of the products that Smooth-On sells.

http://www.smooth-on.com/

[RCW]

Not sure if this would work, but here's some molding stuff used in the food industry:

http://www.makeyourownmolds.com/silicone-plastique

You could make wheel patterns in chocolate!

Steve

Then if it didn't work, you could smile as you disposed of the "failure."

[SteveM]

Not sure if this would work, but here's some molding stuff used in the food industry:

http://www.makeyourownmolds.com/silicone-plastique

You could make wheel patterns in chocolate!

Steve

Then if it didn't work, you could smile as you disposed of the "failure."

That's why we prototype in Ghirardelli chocolate.

Easy to get the wife to go along too.

Steve