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Thread: Vacuum press for PETG mounts

  1. #1
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    Vacuum press for PETG mounts

    About a year ago I had to quickly make 50 mounts to display necklaces, and we wanted them to "float" in the space, so I ham-fistedly heat formed Vivek sheets (PETG) over an old mannequin using a heat gun and bare hands. They worked pretty well - not perfect, but suitable and invisible, as intended. Now we are preparing an exhibition for next Spring in which we want to highlight the internal structure of historic costumes, and I wanted a more efficient, consistent way to form clear mounts that will support the garments but allow clear sight lines, so I started digging around for ways to vacu-form plastic. We of course have no budget, so I can't really afford high-end equipment, thus the Rube Goldberg device you see below.

    I wanted to share my first attempt in hopes that others have done this and can provide some tips to help us along. Here are the specs: a 1500 watt Quartz IR ceiling mounted heater from Tractor Supply Co., wood and metal scraps from my shop, aluminum flashing to line the box, and aluminum channel to support the frame that holds the material. I set it up as I did to minimize the transfer time from heat source to vacuum, and also to allow some of the IR to warm the mold. I was a little worried at first by all the warnings to keep the heater 3' away from combustibles, but for the short duration of the heat cycle it did not seem to be a problem. The material I used was 1/16" thick PETG, and it took about 10 minutes to get the sag you see. I think I may need to move the material a bit closer to get it really stretchy, but I was also being a little impatient. The heater has a 750 watt or 1500 watt option, and I started with the lower setting but it didn't quite seem up to the task. The shop vac seemed to get enough pressure, but there are some pinhole leaks in the platen that I need to find.

    Anyway, have a look and let me know what you've done different/better so I can learn more!

    Cheers,

    Jim Williams
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  2. #2
    PACCIN Advisory Committee Member T. Ashley McGrew's Avatar
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    Hi Jim,
    Nice set-up! I am curious to see what input you get. I think will pass on the link to the list to elicit more possible responses.
    Thanks for sharing your research!
    Ashley
    T. Ashley McGrew
    PACCIN Advisory Committee member

  3. #3
    Member Jamie Hascall's Avatar
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    Wow Jim, that's a great little setup. Apart from the obvious thought of foam tape around the edge to help with leaks, I can't think of anything I'd want to modify. I think it's mostly a matter of getting it dialed in. Are you blessed with a set of garments that are similarly sized or do you have a number of sizes of shoulder molds to use? I look forward to seeing your finished use of the Vivak shoulders and how you support them.

    Good luck!
    Jamie

  4. #4
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    Thanks, Jamie! You're the guy that got me started with Vivak, back at the mount making forum in DC a few years back. Don't have the complete checklist so I'm not certain about sizes and varieties, but we plan to sculpt a form of plasticene and cast it in plaster for the final vacuum forming run. I'm also planning to do a set of "hips" to mount skirts to. The leak actually turned out to be a void in the plywood I used for the frame, so it was an easy fix. Also used thinner (4 mil) Vivak which worked better. I'll keep this updated as I learn more.

    Jim

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