Monthly Archives: September 2013

Vacuum former; part 1

Years ago I had a freelance gig building a proof of concept model for a type of modular part. I whipped together a rapid prototyping machine out of a drawer, a bit of wood and aluminum scrap, my shop vac, some binder clips, and oven.

Not a bad test pull for hacking together a vacuum former from scrap on hand.

It was crude, cost almost nothing to make and worked pretty well. I ended up making a bunch of things with it, because it was fast and easy.

bianca armor

The lightweight armor for this puppet was pulled from solid resin prototypes in the course of an evening.

Eventually when the oven was replaced, I was asked not to put plastic in the new one anymore, since I had no immediate need for fast hollow plastic forms, I boxed it all up and put it in storage.


Returning to the former

Recently I found reasons to to develop a larger one, partly for some of the larger Drab Future models and partly for a friend, so I brought out the old machine and hacked apart an old space heater I’d had lying around along with some more scrap materials to try it out. Think of it as a ‘proof of concept’ basically to see what I ccould do in a night to get this up and running.

This looks like the heater;
http://www.infraredheaters.com/mcm.html
heater

Wired the whole thing into some frame made from aluminum.
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And this is the arrangment with the new frame and binder clips
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Once the plastic starts to droop, lift it off and drop it onto the platen and flip on the vacuum.
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Things to look out for; As you can see the heat is a bit uneven, so I need to build a better insulated box and better distribute the heat over the entire surface and I don’t think the shop vac I was using had a very good seal.
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It’d be nice to get this mini machine working, but it is hardly a priotity. I’m going to need something better, bigger, and more modular, but I’ll keep it around and use some scraps to fix it up.

Design Goals

  • Armor factory, want to be able to quickly form wearable suits of armor, estimate a maximum 2×2 foot max size needed.
  • Small foot print, Not a lot of room in the studio, so looking at an overhead heater, and storage space below the table.
  • Work surface as multi-use work bench table, large forming surface, want platen for 2” square frame and interchangeable for 1” squares as well as single hole for mold rubber evacuator.
  • Started drawing up some designs, based on a few ideas I’ve seen online;

    Untitled
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    Construction

    So I’ve begun by making the platen from parts I had on hand and looking at the size/shape of the work surface to see what will be useful and comfortable, mostly just holding up poarts to visualize and get the feel for it at this stage.

    Untitled

    I opted for 2×2 because that seems to be a standard size of available plastic sheet, and should allow me enough working space for even large parts of armor.

    Untitled

    This is about as far as I’ve gotten so far, and will need to consider picking up parts and materials to go any further.

    Parts List

    Looking at this list the estimate is about 300$ in parts, I’m hoping to make that less by being inventive…

  • ½-¾ MDF for table construction
  • ¼-⅜ Hardibacker for oven box
  • wood/metal support to elevate oven box
  • wood/metal frame to hold plastic
  • frame hinges
  • tracks for frame
  • clamps from track to frame
  • Heating element
  • Source of Suction

  • Expendable Materials

    24×24 sheets of ABS and/or HIPS at 1-1.5mm thickness
    Currently it appears that they run about 8-10$ a sheet, not too bad, but considering the ammount of test pulls I need to do… yeah.


    Heating element

  • Quartz patio heater
  • 50$ (might need two)
    26.5 x 5.2 x 14.2 inches

    http://www.amazon.com/Ceiling-Mounted-Workshop-Heater-Halogen-Light/dp/B002VMKCWQ/ref=cm_cmu_pg__header

  • Modular Heater Kit and protoform plans
  • $235 (220 volt)

    http://www.build-stuff.com/FastHeatFlyer.htm

    Vacuum/suction source
    Looks like there are two options here, need to look at shopvac vs pump/tank. Shopvacs seem to be sorted by two factors, size and horsepower. I don’t need a very large one, but one that has a large force behind it. The advantage of a Ahopvac is that I won’t need to spend more time/money on plumbing and filters, and I’ll have an new additional tool for the shop. The downside is that it’ll never create as much force as a smaller pump/tank arrangment, and wouldn’t be able to pull double-duty de-gassing mold rubber.

  • Shop vac
  • I’m unsure what constitutes “enough” suction in terms of hp, it’d depend on the gauge of the plastic and other factors, but I doubt a shopvac could ever give “too much”.

    3hp 44$
    4.5 66$
    5hp 80$
    6hp 100$

  • Air tank + pump
  • I have a pump which should be rated pretty high, but needs testing as its been stored for awhile now. This solution will also require more set up for addign valves and fittings, but ultimately will be higher quality. Additionally plenty of pumps available online, ranging from $40-300+. The ratings for them refers to how many CFM, cubic feet per min, they can evacuate.

  • 3CFM $55
  • 33$ 5 gal tank
  • additional valves and fittings
  • Reference Notes

  • Can’t start a build like this without crediting Doug’s plans here;
    His machines represent the “right” way of doing this, and most of the examples you see online are modeled after his designs.
  • Another build worth mentioning is from Volpin prop’s blog
    He has built two and documented the builds for both of them, but I’m particularly impressed with the DIY nature of this first smaller build.
  • I’m very impressed with James of Xrobots.co.uk’s super simple Vacuum former tutorials here;http://xrobots.co.uk/vacuum/ It was his use of the Quartz heater that convinced me that it’d be a good idea.
  • Lastly I wanted to make note of this thread:

    http://www.tk560.com/phpBB2/viewtopic.php?t=1867

    It appears he is using the same heater I have been looking at and a similar format and has been running into the same problems I would be, i.e. the wood oven box heating, so it’ll be good to study how he has solved them.