August 17, 2004

Marla's New Arm

A couple of days ago I poured over a half-gallon of polyurethane rubber into the silicon mold of Marla's arm.

Last night, we removed it from the mold.

Getting the silicon off was HARD! Once I got the mold inverted off of the upper arm, Marla got a firm grip with both hands on the arm. I grabbed the edge of the mold, put my feet on Marla's legs, and pulled. And pulled. Pulled some more.

Eventually, we got the wrist to stretch around the palm and the arm came out.

There was one bubble in one finger. I poured the rubber with the mold at a sub-opt angle, and my efforts at de-bubbling were not sufficient. The surface finish around the hand is a bit off, too -- I think there was still some moisture there from when I measured the volume of the arm.

Despite the extreme effort involved in removing the mold, the silicon survived! I was planning on doing a second pour with the mother mold in place, to get a "bloated" arm and hand.

I think I'm going to do another regular pour instead, with a different angle to avoid the bubble problem. It will be a tricky pour angle, but I should be able to make it work.

I don't think I'll have enough poly left after this to do the bloated arm... but if I do, and the mold survives this second pull, I'll do the bloated one next.

I'm expecting stacks of stuff from UPS this week, too. Next week will be an orgy of SFX development! Wheee!

Posted by Edwin at August 17, 2004 09:26 AM
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