Hollow casting

Drewskiman

So I've been trying to make hollow molds of my arms and I'm just wondering if there's an easier way to hollow cast rather than simply turning the mold until the silicone sets. Don't get me wrong it works but it's very time consuming. Any help would be appreciated. Thanks!

Chris Ellerby

If rotocasting (turning the mold as the material sets) does not meet your needs, for example, you need specific thicknesses in different areas, using a mold core would be your next option.    This would require redoing your molds though, and complex shapes like hands would likely require a multi-piece core that can be disassembled to allow for demolding. 

Another option would be to use thickened silicone and brush it into the mold in multiple layers, which would likely take as much time as rotocasting.

Drewskiman

So manual rotation is the best bet. I just didn't know if there was a machine that could hold the mold and turn it. Thankfully I keep the room pretty warm so the silicone sets within 15 minutes. Thanks for the help Chris. 

Alexander H

If you are just spinning it on one axis, would it be possible to set it up on something like a spit rotisserie? One that you can adjust the speed of to get it right for your needs.

Drewskiman

The room I work in is pretty warm so manually doing it only takes 20 minutes but that's still a long time. I've looked up machines that would be capable of holding the mold but there's nothing. 

Chris Ellerby

@Alexander H With rotocasting you usually want to rotate in all orientations, otherwise, you will get uneven buildup in some areas.  They do make rotocasting machines, but most folks just build their own.

/Chris

Drewskiman

Now where in the world would I find that?

Darrell Green

 Here is the how-to version I found on my search after @Chris Ellerby posted, I didnt know they existed:

https://makezine.com/projects/diy-rotocaster/

I didn't look for a kit or purchase option but they are a real thing so am sure you can buy one.