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 Small Vacuformer 
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1047
Location: Lacey, WA USA
The deadline for this is to have it ready for Arts Walk and the Tinkering Adult Swim at HOCM. This will be the place to discuss this project online.

I have a lot of vacuformable battery trays that flatten right back out when heated. Just a bit over 9x12 inches and any color you like as long as it is black or clear.

This will be a project log about building a small vacuformer. A standard size of thermoformable sheet is 12x12 and 12x18. The vacuformer can be larger than the 9x12 battery trays, but I'd like to keep this one fairly small and portable.

There is the style that has the heater on top suspended over the vacuum bed, with the sheet held in a holder that slides up and down the supports. I have a lot of 1 inch straight pipe we can use for the supports. Like the Formbox (small) or the Centroform EZForm.

http://www.3ders.org/articles/20160502-mayku-formbox-plastics-factory-brings-mold-making-to-the-masses-through-kickstarter.html
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http://www.robotshop.com/en/centroform-ezform-tabletop-vacuum-forming-machine.html?gclid=CjwKEAiAoOvEBRDD25uyu9Lg9ycSJAD0cnByHrFQXu-tW0fd0uHmjroAatextD-ZR7x9nCzX1s5pxxoCL5fw_wcB
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Or with the heater sitting to one side of the vacuum table with the plastic held in a holder hinged between the two. Like this Hobby-Vac.

Image

That company sells plans for that and another with the heater overhead. I don't think we need plans, do we?
http://www.build-stuff.com/

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Steve Greenfield AE7HD


Wed Feb 08, 2017 10:25 am
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Joined: Sun Aug 26, 2012 2:08 pm
Posts: 1047
Location: Lacey, WA USA
I have decided that, although the hinged model would be MUCH simpler to build, I feel there are many arguments against it.

1. The plastic sags into the heating element, accelerating heating of the part that is sagging.
2. Things can be dropped into the heating element. Dust, sawdust, and hair will collect and burn.
3. A protective mesh will get hot and melt the plastic.
4. Fingers can easily get into the heating elements.
5. As the plastic is moved from the heater to the vacuum bed, it is being moved through the air, cooling it more along the part furthest from the hinge.

So I'm going with the heating elements overhead.

I don't like the heating elements currently at OlyMEGA, earmarked for a vacuum former. Again, there are a number of factors:

1. They are rather expensive to replace. They are replacements for an expensive space heater. The fact that they burn out so often that several websites carry them, worries me.
2. They are not sealed. Oxygen from the surrounding air will get in and oxidize the filament.
3. They are not built for easy replacement.
4. I will have to build a heat resistant holder for them.
5. They are meant to have air blown across them in normal operation. We need something that radiates heat. IE, infrared.
6. Everyone has been handling them, so the glass is covered in skin oils and microfractures.

I have done some experiments and decided to modify some quartz-halogen lights. I have a set, four heads, and no longer use them. There is a glass shield to block UV and IR. With it in the top of the box, they will only be on when a sheet of plastic is blocking the light. Even with clear plastic, any UV released will only be viewed indirectly.

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Without modification, they get VERY hot. I did not realize just how hot. I opened the glass cover. I placed one of my thin battery trays about 2 inches over the light and within seconds it was smoking and several holes had appeared where the plastic was thinnest.

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FullPower2inches.jpg
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Then I tried with another sheet. This one isn't stretched out as far, so it has a better chance of flattening out. I held it 6 inches away and kept flipping it over so it would get heated evenly and flatten out. It came out much better.

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FullPower6inches.jpg
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Note that this was only one bulb, no frame, so it only heats the center. If I turn the power down with a lamp dimmer, it should heat more gradually and so not require flipping.

Both styles of battery tray have the complication of not having a flat edge to clamp, and have slightly different cutouts around the edges. However, they both could be clamped with a thin edge of wood about a 1/16 inch wide around the inside edge.

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Steve Greenfield AE7HD


Sat May 13, 2017 3:19 pm
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