Vacuum molder

[Frogwagon]

So I'm in the planning stages of making a vacuum molder to make bodies, wings etc... Any ideas on on the heat source other than an oven or heat gun?

[kaiser]

ceramic heat lamp
infrared heat lamp




wood fire?

[Frogwagon]

i was thinkin about buy a small cheep oven and pull the heating element out of it. I cant find a body that i like so im goin to make my own, make a wooden mold and pickup some sheets of lexan from the craft store here in town.

[kaiser]

I'm very interested in your results.

[jwscab]

Yeah, I would say the elements from a toaster oven, or maybe one of those little space heater elements. With insulation done properly, it would work out OK I think.

Are you designing a molder how the typical ones work, where you have the heat side, then the vacuum side and the sheet flips between the 2 in a frame?

[Frogwagon]

me too lol, ill be able to use up to a 36inX18in sheet of lexan so i can make bigger bodies if needed. Most home-made vacume molders ive seen have only been 12X12.

[jwscab]

yeah, you are going to have to be very careful with temp control with that large a sheet, with drooping and possible tearing, just FYI......

[Frogwagon]

Yeah thats why im tryin to figures out a good heat sorce. When its done it will have a few different size tabes i can switch out, it will just go up to 36x18. what ever i use to heat it will be on a frame right above the vacume table, that way i can just slide the lexan in a frame on rails right over the mold. Most vacume molds ive seem have been setup that way because of drooping(well that what the guy that work at a plastic factory in town told me)

[ROH73]

Home vacuum forming lexan is not easy. It took me 6 months to develop my vacuum former and I have several hundred dollars invested in it. Heat source and its placement are critical to have even heating without hot/cold spots. 36x18 is a huge vacuum former (it's a professional 220v size); there's a reason the hobby ones are 12x12 or so. The one I made is 12x24 and I use two 1500 W heating elements. Vacuum source is also critical; a shop vac is not enough to pull down lexan; 25 or more inches of Hg in a reservoir is required. In addition, lexan absorbs moisture and must be dried prior to vacuum forming; if not bubbles will appear in the plastic as the heat converts the water to steam.

I recommend you get this book and go from there: http://www.amazon.com/Do-Yourself-Vacuum-Forming-Hobbyist/dp/B000KBEU3W

Regards,

Robert

[Frogwagon]

I have a vacume pump off a cnc vacume table so i got that part covered(if its not too much), i also have a peice of 1/4 inch alum. plate that i plan on using for the table. I have though about using gas for heat, i have a 36X18 propane heater for baking paint(thats where i got the max size of 36x18 from). Ill have a few frames that will hold the lexan 12x24 bein the most common one ill use, 12x12 and 18x12 are 2 other ones im goin to make. i know a 36x18 sheet of lexan will be a pain to heat without getting cold spots wich i may never get to work but it will be able to hold a sheet that big. Ill have to check out that link and see what i have left out.

[ROH73]

It sounds like you have a good start. As long as your vacuum pump can pull down to about 25 in Hg, it should work well, but you'll also need a vacuum reservoir to rapidly evacuate the total volume of air under the mold. Lexan needs to be pulled down in about 1 second because as soon as it leaves the heat source, it begins to cool and harden quickly. Within only about 2 seconds it can no longer be formed into small details or sharp corners.

Also, I can't stress the drying part enough; any moisture in the lexan will show up as bubbles in the body.

Good luck!

Robert

[Frogwagon]

Are there any other materials i can use beside lexan? i head that polystyrene can be use. And how thick should the material be?

[ROH73]

For clear, PETG (what soda/water bottles are made from) works pretty well, although it's not quite as good optically and some question its durability, but I've never had a problem. Thickness for 1/10 car bodies is 0.030".

[Jay Dub]

I helped build a vacuum former for our ID department at State, and ROH73 is quite right. We used a vacuum pump to provide the HG, but used a large air tank (off of a compressor) to provide the volume. Not practical for a production environment, but perfect for personal use. -Jeff

[Frogwagon]

I have a pretty good size tank but dont know what PSI to run it at before it would be too much. It a 35 gallon tank that can handle up to 300psi i know i sont need that big of a tank but its all i have for now.