Scratch Build with Resin Molds

[Hollywoodkbl]

Sorry, maybe this post should go someplace else but I was looking for someone out there who knows how to make a resin mold. What materials do I need and how hard is it to make a mold using resin? Is this how scratch builders make copies of things? Any help would be great. Oh, if you have a plastic part you want to duplicate, how would you do it without ruining the original part?

[Dubar1]

Try Smooth-On for liquid rubber mold material:

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

First you need a master part. I've made them out of wood, metal, and plastic.

Next you need to make the mold. I've used Smooth-On liquid rubber for a few years now.

Finally, you need resin to pour your piece. I've been using Bondo Liquid Resin which is available at Wal-Mart and Auto Zone in quart and gallon cans. A lot of other people use other materials other than the Bondo stuff.

With that said, all of what I've done has been in 1/6th scale. Unless you're making a lot of pieces mold making doesn't seem the way to go. If all you need is 2-4 pieces I've found it easier to just make 2-3 more masters. It is kinda fun though to make your own.

You can also try vacu-forming, although i haven't tried this yet:

http://www.warmplastic.com/

[Hollywoodkbl]

thanks, does the liquid rubber work for plastic. Lets say you want to make a mold of some plastic parts that came in a model tank kit, would you use this. Do you need a releasing agent for this? This process seems complex, is it for someone who's never done it?

[Dubar1]

I've been using their ReoFlex 60 liquid rubber to make the molds.

If you have a master piece, all you do is make a box (I use small cake pans or even Legos) and secure the master to the bottom. Spray it with mold release (Smooth-On also carries this), mix the liquid rubber and pour. The ReoFlex is a 1:1 mix and pretty easy to use. Let it cure overnight and you're ready to start casting.

Here's a couple of pix of a 1/6th civil war cannon wheel I made:

The master piece:


The 2-piece mold:


The 7 pieces to the wheel:


The finished wheel:


A 2-part mold is necessary if the piece has detail on both sides. In this case the wheel spokes were round on each side. If it's going to be flat on one side then you only need a 1-part mold.

[Gunner]

There's a great tutorial on mold-making on this board:

http://p216.ezboard.com/bonesixthcustoms

[Hollywoodkbl]

Those pics help some....but how do you know if you need a two part mold, and how do you do a two part mold? Do you need clay for that...how do you make sure the two halves line up? Sorry for all the questions