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vacuum for molding bodies

vacuum for molding bodies

Old 01-26-2007, 09:32 PM
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how many inches of vacuum is needed to pull lexan to mold bodies? i have an old high power vacuum pump just taking up room in the closet and thought this might be a good way to put it to use.
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Old 01-26-2007, 11:41 PM
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i think you can find anything really with google

http://www.google.com/search?sourcei...+forming+lexan


http://www.build-stuff.com/1001plans_hobby_vac.htm
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Old 01-26-2007, 11:45 PM
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Isn't the lexan heated until it is soft before its molded? Wondering if you realize this. We used to have a machine to do this in high school and it worked great for duplicating items. I would typically make a plaster or WEP (water extended polyester) mould (or is it mold?) over which the plastic would be molded. It is a sheet, clamped in a frame above a heater element, which when soft is lower over the object which sits on a perferated surface through which the air is drawn out. The sheet and frame is lowered, the air quickly drawn out, then you pause while it cools and rehardens.
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Old 01-27-2007, 12:09 AM
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yes im aware i need to make a table and frame, and that i have to heat the plastic. just wanted to know if the pump i have is strong enough to do the job. i havent hooked it up to a vacuum gauge yet but i will if someone can give me a definative answer.
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Old 01-27-2007, 12:28 AM
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There are a couple major factors, only one of which is IF your pump draws down to vacuum. The other factor (and where lesser pumps fail) is you've got to be able to bring a substantial VOLUME down to vacuum and do so fairly quickly.

Then things like drawing hole diameter and length add into it. And what thickness material you plan to use (Protoform "light" or Tamiya)?

This isn't something anyone here has experience to answer for you. Time to go to the Vac-Forming sites and fora.

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Old 01-27-2007, 01:42 AM
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we make speaker pods out of 1/8" abs plastic using a dayton heatgun and a shop vac with no problems
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Old 01-27-2007, 03:21 AM
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Vacuum being the absence of matter, it will not take much of a pump to pull a thin sheet of pliable lexan over a mold. The hole diameter and length would be used to help figure the conductance, but that would only be needed if you were trying to figure out the pumping speed. Pump size is going to help with the pumping speed, but pumps of a similar type/family/class are going to have roughly the same ultimate pressure. The chamber/vessel size and desired time to reach a given vacuum pressure are going to dictate the size of pump needed. Although a crude form of a vacuum pump, a shop vac theoretically would be more than enough to pull a lexan body as AZfabguy says. A strong vacuum and a good seal will pull more vacuum than most people realize

No vacuum forming experience, but I did stay at a Holiday Inn last night jk... 13 years of playing with high vacuum systems has taught me that vacuum sucks
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Old 01-27-2007, 06:28 AM
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A local guy here makes his own 1/12th scale and touring car bodies. They look really realistic and good.
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Old 01-29-2007, 05:47 AM
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I'm working on one at the moment. Its a fun project.
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Old 01-29-2007, 05:48 PM
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Anybody else old enough to rememberr Vacuforms as a kid? You heated a Velveta sized piece of platic hot enough to burn your skin, then put it over a mold of a car and pumped the handle to vacum it into shape. If you did'nt burn yourself, you got a chance to slice your skin cutting the car out.

There were'nt many personal injury lawyers around at that time.

After your Mom kicked you out of the house because of the smell you went outside and threw Jarts straight up in the air and tried to catch them!
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Old 02-05-2007, 01:58 PM
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People want to know how to do this. Is it just not as hard as people make it out to be? I would love to be able to make my own touring car bodies. Everything from forming the clay or resin or whatever it took.

God knows that the companies who sell the bodies dont want a lot of folks making their own.
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Old 02-05-2007, 10:08 PM
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Sounds like you guys all need to get in the body business and put the big guys out of work. Got if all figured out....
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Old 02-05-2007, 10:31 PM
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Originally Posted by snoopyrc
People want to know how to do this. Is it just not as hard as people make it out to be? I would love to be able to make my own touring car bodies. Everything from forming the clay or resin or whatever it took.

God knows that the companies who sell the bodies dont want a lot of folks making their own.
The one I've seen locally is carver out of baltic birch and then some bondo or something to fill some spots smoothed over with alot of small holes drilled in it to suck the lexan inward ...Something like that.
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Old 02-05-2007, 10:42 PM
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I've got a production vacuum former in my shop that has been sitting unused for about year. The machine is in great shape. It's a QVAC PC1824 18 x 24 model, so I would think it would be big enough even for a monster truck body. If your close enough to me in central Alabama, you are more than welcome to come make stuff on it. You can look at it at www.qvac.com
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Old 04-12-2007, 07:00 AM
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Another question on this.I have a couple of out of production bodies that I would like to back pour and make for myself. My question is..what can I use to make the mold without damaging the lexan bodies that I'm using? One more,anyone have any leads on where to get sheet lexan of the correct thickness (standard RC body).Thanks,Mario.
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