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BigTallDad

Poor man's vacu-form

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I was recently in Rodeo Shack and saw some circuit board for experimenting. The board had a LOT of small, evenly spaced holes. After buying one (less than ten bucks, if I recall) and scrounging up some scrap lumber, I came up with this.

Vac0001.jpg

The bottom was deliberately left longer so I can clamp it to a work surface. As I said, there are a LOT of holes.

Vac0002.jpg

There is a hole in the back for my shop vacuum; the hole in the front, in combination with the gate, allows me to lightly hold part in place whilst heating it with a heat gun (from Harbor Freight). When the plastic is soft enough to form, close the gate and let the vacuum do the rest. For forming smaller pieces, cut a hole in some aluminum foil and continue to march.

Vac0003.jpg

Edited by BigTallDad

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Cool one .. best home made I've seen .. and to think, I just got a shop vac! :)

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57 minutes ago, Ace-Garageguy said:

Nice box, Ray. Looks good. Any additional wisdom to impart as to heat sources, handling hot sheet plastic, etc?

I use an el cheapo heat gun from Harbor Freight, and made some frames that look like large, rectangular ping-pong paddles with a large hole in each (about three or four frames, 3/8" plywood or 1/4" pressboard). The hole size varies depending on how large the part being formed is, and the paddle frame is always slightly larger than the vacu box. Imagine picture frame with varying widths on the sides and having a handle.

The paddle approach allows you to focus heat on the plastic, while keeping your hand away from the heat source.

Attach a piece of plastic to the paddle (tape, clamps, etc.); heat the plastic with the heat gun until the plastic is sagging/drooping (it might take a few tries to learn the best "softness") then place the sagging plastic on the vacu-form box, and close the vent. If necessary, continue to heat. You can do multiple pieces, and they would be held in place by the vacuum of the box with the gate open. If the parts are too small for this, then use double-sided masking tape, as in that used to replace grips on golf clubs.

After the plastic has cooled, remove it from the frame and trim etc. Windex can be used to accelerate the cooling process...the evaporating Ammonia helps a lot.

I used to make the buck out of wood, lay the plastic over it, and heat it until the vacuum took over. I had to use wood, because heating plastic on top of a metal buck required that the buck reach a very high temperature, often leading to less-than-desirable results. A friend of mine built a similar box and shared his approach described above.

Bill? Does that answer your question, or did I miss something?

Edited by BigTallDad

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This is good!  So you can heat the piece on the box, to help suck it down, vs. slapping it down and hoping it will take.

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6 hours ago, 89AKurt said:

This is good!  So you can heat the piece on the box, to help suck it down, vs. slapping it down and hoping it will take.

Yes, you can heat the sheet plastic on the box, but the buck needs to be wood so the buck won't melt. If you use metal, the metal will absorb the heat, prolonging the heating and cooling processes.

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6 hours ago, BigTallDad said:

Yes, you can heat the sheet plastic on the box, but the buck needs to be wood so the buck won't melt. If you use metal, the metal will absorb the heat, prolonging the heating and cooling processes.

 I use Corian (used for kitchen countertops), which has a high heat tolerance.  The profiles made from styrene plastic show slight melting.

IMG_8963_Fotor.jpg

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I'm having good results using the cooktop burner, but I can't add heat if not completely sucked down.

IMG_8973_Fotor.jpg

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48 minutes ago, 89AKurt said:

I'm having good results using the cooktop burner, but I can't add heat if not completely sucked down.

 

That's where the heat gun comes in handy. A 1,500 watt, dual temperature gun costs about $15 at Harbor Freight.

Drill Master 62340 1500 Watt Dual Temperature Heat Gun 572°/1112°

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