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Closed shell adventure - new tool: rotocaster
Closed shell adventure - new tool: rotocaster
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Closed shell adventure - new tool: rotocaster
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Drew Diller
Drew Diller
posted 12 Years Ago
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Hey all, I'm determined to get complex shapes working in a DIY environment for bladder inflation molded hollow carbon parts.
My major sticking point has been making custom shaped inflation bladders.
I don't mean airplane fuselages - if that is the letter "I", I am trying for shapes like "K" and "J" and eventually even shapes that get out of a single plane, as in, where fused seam lay-flat bladders simply won't work (apart from the fact that I keep bursting them... I've tried, a lot).
I learned a few months ago about rotocasting. It is used to make large, hollow parts of little material value using as little material as possible. Mannequins and plastic lawn ornament alligators are easy examples.
After some good guidance, including from compositepro (thanks dude), I decided to build my own rotocasting machine. Why?
...Have you priced a rotocasting machine lately?
HOLY CRAP. No thanks.
Further, getting a small run of bladders from a composite specialist company is very expensive. They operate in bulk, it's too expensive to justify as a small fry. Don't believe me? Do your own homework, I am sure you will find the same. If not please send me a message, LOL
I made this one for... I'd guess $300 to $400, I'm not exactly sure. I made several mistakes in hardware which cost me extra. One thing I was having trouble with was finding a suitable motor for cheap. Finally landed one recently at a misc surplus store, found a bin of high quality motors for $9 a pop (original price > $100). I am now a surplus store junkie...
I don't have any results yet, I'm running the first resin test right now! Here are some videos of the machine in action:
Internal view:
(This one may affect people who get motion sickness easily)
http://www.youtube.com/watch?v=qcsweEzvfHw
External view:
http://www.youtube.com/watch?v=WdHNn7jhz9A
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Drew Diller
Drew Diller
posted 12 Years Ago
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First test, not usable, but not horrible for a first test:
http://dillerdesign.com/random/bike/testing/20131119_182832.jpg
http://dillerdesign.com/random/bike/testing/20131119_182845.jpg
It'll take some more tests, certainly, probably multiple resin cures for a single bladder, possibly a different resin altogether.
Encouraging, however!
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LaxFriedrichs
LaxFriedrichs
posted 12 Years Ago
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Drew, thanks for the heads up via email.
Good progress. Are you using your actual mold, or a facsimile with smaller dimensions? Maybe a vacuumed formed plastic mould copy?
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Drew Diller
Drew Diller
posted 12 Years Ago
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I'm just using a Gatorade bottle for testing purposes. Don't want to bother with my actual mold until I've figured out how much silicone is needed per layer per square inch.
Here's a two-layer-batch test from last night:
http://www.youtube.com/watch?v=-s2bPytiZ2c
EDIT - you can see how the base got kinda screwed up, I wanted to apply more layers but I broke a cog adapter on my machine!
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12 Years Ago by
Drew Diller
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Matthieu Libeert
Matthieu Libeert
posted 12 Years Ago
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thanks for sharing! great project! I'll start with some similar stuff soon
Matthieu Libeert
Founder MAT2 Composites X Sports
website:
www.mat2composites.com
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20_rc51_00
20_rc51_00
posted 11 Years Ago
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Interesting!
So you are trying to test what thickness of bladder you need to keep it from bursting when you inflate with pressure?
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