[Robotgroup] Casting plastics

[John P. Funk]

Hi Nick,
I have been a model builder for many years. I have also had success casting 
resin model parts. the first and most important step though is making a 
mold.

The engineering of the mold determines the success of the cast parts, how 
many undercuts and sections the mold requires and the resevour system that 
allows the excess flow of the resin will decide how "clean" the molded part 
will be after removed from the mold. I have produced fairly clean model 
parts without the use of a vacuum chamber and have done so with a pretty low 
investment budget. You will want to use a silicon mold base, DowCorning 
makes a good product, (RTV silicon was the last product I used to make this 
model kit): http://www.cozmicfunk.com/arac_model.html

It had taken me years and many experiments to get to a point of being able 
to produce consistent model parts that I could use with out too much clean 
up. Were you at the SXSW Dorkbot/Make exhibet last March? I had a display 
set up next to the stage with models and light fixtures. The "Blade Runner" 
looking cityscape I made used dozens of resin cast model parts:
http://www.cozmicfunk.com/MLTInterstellar.html  that technology took me one 
year of practicing to achieve.

Be prepared to invest some time, some money and R&D into this, otherwise you 
could send your part off to Garage kit manufacturer and have them make the 
parts for you. Try google searching Garage kits and silicon molding, I am 
sure there are resources out there that may help you get started. Just like 
so many things, I can help with advice, but you will have to get own your 
hands dirty (and smelly: resin stinks, it can be very toxic). These 
materials are so toxic and need curing time, I can longer deal with the heat 
and lack of appropriate workshop area in my back porch.

For future reference, I am looking at converting my garage/store room into a 
art/film production shop if I get my refinancing.
I plan to resume making molds and custom models once I have a well 
ventilated and Air Conditioned workspace. More robots and spaceship models, 
that's what I 'm talking about :)

John P. Funk




----- Original Message ----- 
From: "Nick Pietraniec" <mlists at resistive.net>
To: "The Robot Group Mailing List" <robotgroup at puremagic.com>
Sent: Sunday, May 20, 2007 10:58 PM
Subject: [Robotgroup] Casting plastics


Does anyone have any experience casting resin?  I'd like to do
something similar to the taillight casting in these howto's

http://www.alumilite.com/index.php?page=info&type=HOWS

Just wondering if there's someone out there wants to offer some words
of encouragement or warning about what not to do.  My impression is
that in order to end up with a reasonably bubble-free cast I'll need
to use a vacuum chamber to remove bubbles.  It looks like the cost of
entry into the world of casting is relatively low, so when I fail I
should only be out a few bucks.

-Nick
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