Author Topic: Plastic vacuum former.  (Read 9422 times)

Offline Dawai

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Plastic vacuum former.
« on: November 27, 2013, 01:48:31 PM »
New adventure for me, vacuum forming. I set up a test bed, a OSB wood box for the vacuum, set it on the cnc table and told it to drill me a few hundred holes, (box is bigger than the cnc stroke) so I had to move it about reorienting it.

Did a vacuum trial, a 1/2hp Gast vacuum blower versus the Supposedly 4hp 12o volt shop vac.. the shop vac won, but if it must run continuously the 3phase one will be installed. THE shop vacuum is a limited duty brush motor. Extra table holes can be covered with butchers paper, or cardboard.

FIRST trial, a slice from a blue 55 gallon plastic barrel, 1/4" or so thick, making a hammer tray for the "fanciest hammer I own". Not exactly what I wanted. I used the kitchen oven I use for powder coating to heat the piece of plastic in a wood frame, 300 degrees for about 12 minutes. It was like a wet blanket when it came out of the oven, you have about three seconds to set it onto the vacuum table, I took about ten since it was in the next room..  (so it needs a closer heat source)

It worked well enough to set up a full time vacuum table with lifts on heater and vacuum table.

Plan is the two elements tied to a SSRV (variable voltage solid state relay) in the split steel drum. Radiant heat, NO timers here, and I looked, so I had to take a old opto22 serial card, and the laptop to make a two stage event timer, one for heating time, one for pressing-vacuum time.
 THE cnc shop computer can do this as well, using a usb-serial adapter, then a 232-422 current serial adapter for the antique opto22 cards. (bought off ebay cause I was familiar with them) They were going onto the beer cooker to automate it, valves and timing.. but.. it is so simple it really does not need it.

  Any suggestions to make it easier? know of a real cheap cycle timer other than a brick plc??
I Hung a 24 foot Ibeam this morning in the ceiling by myself, programmed a Arduino this afternoon for a solar project, Helped a buddy out with a electrical motor connection issue on the phone, then cut up a chicken for Hotwings. I'd say it has been a "blessed day" for myself and all those around me.

Offline greenie

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Re: Plastic vacuum former.
« Reply #1 on: March 17, 2014, 08:14:22 AM »
Just a few quick observations, the material your using does not really do this form of moulding much justice at all.
For the BEST performance of any plastic when heat/vac forming, has got to be polystyrene, the thinner you go, then the quicker it droops under heat and the quicker you have to be with the vac table right next to the oven.
A normal oven will soften Polystyrene very easily, a fan forced oven is even better and a tad quicker.
By having the vac former on the bench right next to the oven, means only a few seconds pass between removing the frame from the oven and then you slam on the vacuum cleaner to do the forming.
An oven with a glass panel in the door, is the easiest/cheapest timer I can think of. Just use your eyes and when the polystyrene droops enough in the frame-----, well open the door and grab the frame, then slam it over the vac table and hit the switch, it's done faster than what you can read this sentence.
For an excellent cover for your extra holes in the vac table, then go get a vinyl floor tile, cut the centre out and you now got a smaller vac table.

Here's what my system looks like, as you can see it's sitting on top of the stove, I just push it to the left so it's on the bench top, works for me.

regards  greenie 

Offline BaronJ

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Re: Plastic vacuum former.
« Reply #2 on: March 17, 2014, 05:25:42 PM »
Hi Dawai,
Grab an old microwave oven that has an electromechanical timer.  Not very precise but you get a nice "Ding" at the end.  :med:
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Best Regards: