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Author Topic: vacu-forming  (Read 425 times)

pdrake

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vacu-forming
« on: August 29, 2010, 05:57:24 PM »
i just got asked to provide a large quantity of chocolate tikis for a party. i have a small, silicone mold right now for my R&D purposes. i think i need poly molds with large quantities of each design.

i can't seem to find a local vendor to make these and the online ones have been a little vague.

any advice would be welcome. i'm not against making my own unit, i heard you can do it with a shop vac. i also have a vacuum pump.

 :confused:
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you'd be surprised how much a nutsack can stretch. you have to stretch it yourself, not a woman. they don't do it quite right.

random axe

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Re: vacu-forming
« Reply #1 on: August 29, 2010, 06:01:11 PM »
I've seen it done but never done it.

All those guys (and gals) who have stormtrooper armor?  Most of that stuff is homemade vacu-formed, and consequently there are lots and lots of How It Works websites out there.  Or at least there used to be.

From what I remember, making the mold is the hard part.
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unclejessie

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Re: vacu-forming
« Reply #2 on: August 29, 2010, 07:45:18 PM »
I know candy makers use cornstarch molds all the time for hard candy type stuff.  Not sure if that applies to chocolate.

We have a thermoforming set up at work that we use to make cup like parts.  Probably not exactly what you're looking for but I can take some photos of it when I get back there in a few days.  I'm sure that the hard part will be getting vacuum in the right spots so that it forms over the plug correctly. 

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pdrake

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Re: vacu-forming
« Reply #3 on: August 29, 2010, 08:34:50 PM »
yeah, cornstarch doesn't work for chocolate.

i'd really appreciate a photo. i probably need to put as many masters down and then form over them. there are no undercuts because they were sculpted to come out of molds.

thanks!
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you'd be surprised how much a nutsack can stretch. you have to stretch it yourself, not a woman. they don't do it quite right.

pdrake

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Re: vacu-forming
« Reply #4 on: September 01, 2010, 09:41:05 PM »
this seems to be the easiest, cheapest and most comprehensive how to i've found.

http://www.studiocreations.com/howto/vacuumtable/index.html

i could probably build it in a few days.
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you'd be surprised how much a nutsack can stretch. you have to stretch it yourself, not a woman. they don't do it quite right.

random axe

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Re: vacu-forming
« Reply #5 on: September 01, 2010, 09:59:01 PM »
I . . . uh . . . :confused:  The way he uses "quotation marks" also made me slightly batty, but I realize it's not his concern, yadda yadda.

Honestly, I think that mostly confused me more.  I couldn't figure out how he actually uses that setup until I found the vacuforming demo page.  I was looking at the table and wondering how the frame and mold can both be on it at the same time. 

Industrial vacuforming that I've seen done (to make hot tubs, for instance) uses a negative mold, and the plastic isn't forced into / onto the mold mechanically at all.  A big sheet is just stretched over the top, heated with a clamshell heat-lamp thing that gets lowered over it, and then it's sucked down into the mold.  It takes like twenty seconds to go from what looks like laminate countertop to a perfectly formed hot tub, which is pretty awesome.

With this setup, I'm still not sure how he ensures that the mold doesn't block the airflow.  Of course, if you can make a slightly porous mold, like you do for some of your other stuff, that might solve the problem.

If you use a shop vac for your pump, remember that shop vacs aren't necessarily rated to strain against an unproductive vacuum for minutes on end.  Some models would undoubtedly overheat, since their motors are cooled by the air going through the vacuum.
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random axe

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Re: vacu-forming
« Reply #6 on: September 01, 2010, 09:59:50 PM »
Also, I was gratified to see that in his demo . . . yeah, Stormtrooper armor.

JUST LIKE I SAID.  :lol:  :thumbsup:

And, yeah, I bet you could build one of those with no problems.  Keep us posted.
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pdrake

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Re: vacu-forming
« Reply #7 on: September 01, 2010, 10:43:14 PM »
don't worry, axe, i dun made it better.

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you'd be surprised how much a nutsack can stretch. you have to stretch it yourself, not a woman. they don't do it quite right.

random axe

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Re: vacu-forming
« Reply #8 on: September 01, 2010, 11:29:57 PM »
Good joerb!
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pdrake

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Re: vacu-forming
« Reply #9 on: September 01, 2010, 11:48:20 PM »
i'll probably put a few spacer/wood pieces throughout the peg board so it doesn't sag. just little 1" things or pieces of EMT glued in.
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you'd be surprised how much a nutsack can stretch. you have to stretch it yourself, not a woman. they don't do it quite right.

random axe

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Re: vacu-forming
« Reply #10 on: September 02, 2010, 12:02:17 AM »
You should make one out of an old kiddie-sized air hockey table that you got for $20 at GoodWill or something because one of the legs is broken and then you reversed the fan.
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pdrake

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Re: vacu-forming
« Reply #11 on: September 02, 2010, 12:16:22 AM »
that's a great idea. i'll check at some thrift stores. thanks.
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you'd be surprised how much a nutsack can stretch. you have to stretch it yourself, not a woman. they don't do it quite right.

unclejessie

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Re: vacu-forming
« Reply #12 on: September 07, 2010, 08:52:28 PM »
If you still would like pictures from me it'll be a at least a week before I get back to the office again.
Our set up is similar to Axe's hot tub description. Our "moulds" have a large hole drilled in the back that can feed small holes drilled into the face.  Not really needed since you don't have any undercuts but keep that in mind if you have spots that won't form well.  If you're worried about burning up a shop vac, you could put a hole in the coupling between vac hose and table.  That would keep the vac from deadheading.  A piece of tape placed partially over the hole might be needed to find a balance between higher flow (no tape on hole) and higher suck (hole totally closed).
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