Making rubber mold on painted parts??

[Canneth]

Hi guys,

Newbie here, i have been surfing on this forum for quite some time but never post before, i will like to say every builds i see here are truely amazing, and because of this forum, i have taken up this hobby and stacks of models kit are sitting in my room waiting to be build.

On the other hand, I have some questions that i need opinions from all the experts here before i start, and Yes, I have searched the web, the archive and How-To section but i can't get a definite answers.

i have a set of 1/24 wheels (sprayed with Tamiya TS clear) that i want to make copies of (using the Alumilite starter kit),

Will the rubber mold eat into the paint??
Is it okay to make rubber molds on resin parts??

Any suggestions or warnings would be helpful, thanks in advance!!

[SteveK2003]

The RTV should be OK over paint, but use mold-release to prevent it from pulling off any potentially loose paint.

It is OK to make copies of resin parts, but bear in mind that they are more fragile than plastic, so don't make a mold that you have to wrestle them out of. And remember that if you make a copy of a copy of a copy etc, little abnormalities will compound and the end result isn't always going to be just like the first one. If it's something you'll make a lot of, and have to make multiple molds (Eventually they wear out), then keep a 'master' part specifically for that.

If you need to make a two-piece mold, you can make half of the mold out of clay, and then remove it to replace with RTV later. This is good for oddly shaped parts like seats or bumpers.

I haven't used it much, but I really like the Alumilite stuff. Consider getting a bigger batch of RTV and some extra supplies, as the stuff they give you runs out fast.

[MPWR]

Welcome to AF!

You can definately make RTV rubber molds using masters made of resin. Having been sprayed with Tamiya laquer will not effect this.

Making usable molds of wheels, however, is very difficult. A two part mold must be made, and you need to carefully consider the geometry of creating both parts of the mold, and how you will pour resin into it. Male type wheels (i.e., most Tamiya wheels) with a center pin in particular are very hard to make molds for- if you do not design an adequate pouring vent, the air will not evacuate from the pin area of the mold, and there will be no center pin on the castings.

Making molds and resin castings in general is not hard, and is fun to learn- however, some shapes are much harder to cast than others. Before you attempt to cast wheels, you need to be very familiar with how two part molds work. If you try to copy wheels as one of your first casting experinces, you will very likely be disappointed.

And then there's the issue of tires....

[Canneth]

thx SteveK2003 and MPWR for your valuable comments, i was just trying to make mold on a set of Ferrari F355 challenge speedlines that i have made, not scratch build but a modified wheel based on a 5 spoke wheel from some other kit, it is a female fujimi type wheel so i dont' have to worry about the center pin...

By the way, MPWR, your F50 looks just amazing, can't wait to see you you finish the F40..