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Vacuum Form Materials

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Old 01-11-2003, 11:36 PM
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gwk
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Default Vacuum Form Materials

I'm looking vacuum forming sheet material suppliers (small quantities). Also I don't know if the canopy material is butyrate sheet or something else. Help would be appreciated.

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Old 01-12-2003, 10:34 PM
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linclogs
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Default Vacuum Form Materials

If you haven't gotten one already, I recommend the book, "Do It Yourself Vacuum Forming". It's available from RCModeler magazine. Look in the back of any issue where they sell books, etc. It's on the "Anthology Books" list.

You can also get it on their website, www.rcmmagazine.com then follow links to "books", then "vacuum forming".

One of the sections covered in the book is, "Types of Plastics". That may be just what you're looking for.

Some small suppliers are SIG (expensive) and Riley Wooten's Lone Star Balsa (better). I've tried to find a supplier in my area (such as TAP Plastics) but have been unsucessful. As I only make a few parts for myself on a home-made vacuum machine I designed last year, I haven't been real concerned on cost - yet. If I get into it more heavily later on, I might be looking harder for a cheaper source of raw material.

The photos I've attached, below, show 1. my vacuum machine (it's used with a shop vac) with a canopy mold, 2. the canopy on the mold (after forming), and 3. the finished canopy, which is for a Babcock Models 'Breezy Sr'.
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Old 01-12-2003, 10:38 PM
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These photos show how I form wheel pants. The mold is made by lightly gluing two pieces of soft, Sugar Pine together, then carving, sanding, and finishing (with fiberglass resin) the pant mold. When the mold is completed, the halves are separated, and several short hardwood dowel "legs" (about 1" long) are put into holes drilled in the bottom of the mold (to match the peg board hole spacing on the "platten" of the vacuum former). This holds the mold up off the platten a little so the vacuum from the Shop Vac will pull the plastic clear down to the bottom of the mold. I found that if I didn't do this, the plastic tends to "web" where the mold meets the platten, rather than pulling tightly into the corners. (The short dowel legs were also used to make the canopy but are not shown in those photos). The book tells you that that the vacuum from a Shop Vac by itself is not enough and that you need a secondary source of higher vacuum right at the last second. But I've found that by setting the mold up slightly off the platten, it works ok without a secondary vacuum source. This isn't a good system if you have to make a lot of parts because you make only one piece per draw. But if you're only making one canopy, or 4 wheelpant halves, it's ok.

By the way, the plastic (which is bolted into the frame with carriage bolts and wingnuts) is heated in the kitchen oven until the plastic becomes "floppy", then immediately pulled from the oven, and pushed down onto the vacuum former (with the Shop Vac already hooked up and running). The dowels seen sticking up at the corners of the forming machine register with the holes in the molding frame to make it easier to quickly align everything when pushing the hot plastic down over the mold. I've had excellent results with my system. The parts I've made are as good as any I've seen in kits.
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Old 01-12-2003, 10:39 PM
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Default Vacuum Form Materials

Hmmmmm,
now that gets me thinking. What do you use to heat your material before putting it on the vacuum form????

Thanks in advance
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Old 01-12-2003, 10:56 PM
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I use just the oven for heat (set at the temperature recommended in the book). I keep watching for the plastic to get "floppy", then quickly take the frame out of the oven and immediately draw it down over the mold with the Shop Vac running. I should also mention that I've got a wood box that I use in the oven to hold the frame with the plastic while it's heating. This is in case the plastic sags enough it's got someplace to go, instead of sagging onto the oven rack (wife would definitley NOT be happy about that!). It has room to sag into the space in the box it's sitting on in the oven, if need be. But the truth is, even though I've read stories that you should heat the plastic until it sags several inches, I've never been able to get it to do that. It just seems to change "sheen" and gets, well, "floppy" is the best I can describe it. Maybe it's they type of plastic I've used.

The book describes quite a few different types of plastic that CAN be used, but I've only used the type supplied by SIG and Lone Star Balsa. Neither of these types have been the type that looks to me like styrene (like some of the parts I've seen in kits - the dull, white parts). The type I've used so far (other than the clear for canopies) is actually shiny and sort of opaque and yellowish in color.
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Old 01-12-2003, 11:29 PM
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I've done vacuum forming with ABS, Lexan, and Polycarbonate.
What material did you use for that beautiful canopy? Great finish on your form.

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Old 01-13-2003, 02:56 PM
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The canopy material for the Breezy Sr. is what SIG sells for their clear sheet. Can't remember what it is (I'm at work and don't have their catalog with me) and not sure if the catalog even says which TYPE of plastic this is. That's been one of the problems - most sellers don't state which type of plastic they're selling you - only that it's for vacuum forming and if it's clear (for canopies) or white (for cowls, wheelpants, etc.).

The book I mentioned describes several types of plastic that can be used, but so far, I haven't found a supplier that carries all the different types that you could choose from. I'd really like to try the type I described that looks dull white and is a little on the thicker side - like a lot of the cowls I've seen in some older kits. This may be styrene but I'm not sure about this either. There's never anything in a kit that tells you what type of plastic the vacuum formed parts are made of.
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Old 06-20-2007, 01:11 PM
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Default RE: Vacuum Form Materials

The cheapest place to get sheet plastic is usually a local plastics supplier that has no minimum order, or one that will waive the minimum if you pick the plastic up in person. Call around. Some plastics suppliers have $100 minimums to keep riffraff like us away.

Others have no minimums, or a $25 minimum, and are happy to sell you a sheet or two. (Unfortunately, you generally have to call and ask about minimums; it's not usually in their yellow pages listing or on their website.)

A 4 x 8 sheet of thin plastic is generally cheap, say $15-25, because plastics suppliers price things mostly by the actual amount of plastic, and for a thin sheet, it's just not very much plastic. You can roll a thin sheet up and take it home, and cut it into the size(s) you want by scoring and snapping.

Anywhere else, you're likely to be paying much more per sheet (of whatever size) than you're actually paying for plastic.
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Old 06-20-2007, 01:32 PM
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ORIGINAL: RCKen

Hmmmmm,
now that gets me thinking. What do you use to heat your material before putting it on the vacuum form????

Thanks in advance
I designed and built a bottom-heating oven using a two-burner hot plate and some disposable aluminum pans.

http://www.rcgroups.com/forums/showthread.php?t=621858

It cost less than $30, took less than an hour to build, and works very well for thin plastics. (For thick plastics, it's nice to have a way to turn the heat down a little; the stove-type heat controls don't work very well.)

A standalone oven is very convenient for a small vacuum former. You can put it behind the platen, and just lift the plastic up off it, pull it toward you, and bring it straight down over the platen.




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