8x2.  You mean one of those massive propane tanks people in the country 
usually have?


David P Harris wrote:

> Shawn-
> 28 mmHg  with a 8x2'  propane tank --- the initial rush is to make sure 
> a good seal happens. He said for smaller parts with polystyrene, you can 
> use a old barbeque propane tank with a new valve on it and attached to a 
> air compressor.
> No pictures, but essentially a flat square board with lots of holes, a 
> frame around it, and a chamber below attached to your vacuum.  Set the 
> plastic on top and then heat with a heat gun or hair dryer until 
> sagging, then let 'er rip.
> David
> 
> 
> 
> Shawn Wilton wrote:
> 
>> David, can you get some pictures from your buddy, perhaps a few more 
>> details.  What sort of vacuum are we looking at?  100's of PSI's, or 
>> what?
>>
>> -Shawn
>>
>> David P Harris wrote:
>>
>>> My friend does plexiglass forming.  Wooden frame, kitchen oven 
>>> element for heater.  Large air-tanks connected to a pump.  These are 
>>> pumped out, then a valve opens and the vacuum forming happens very 
>>> quickly. David
>>>
>>> Roland wrote:
>>>
>>>>> BTW, the hard parts of vacuum forming seem to be the matter of an 
>>>>> oven big
>>>>> enough for the work and creating a vacuum source (or is it sink?) with
>>>>> enough volume to draw down the material before the material cools 
>>>>> out of the
>>>>> plastic condition...
>>>>>   
>>>>
>>>>
>>>>
>>>>
>>>> Hi
>>>> I've watched vacuum forming done, and it was a very simple set-up. They
>>>> were forming polystyrene(not foam!)
>>>> The positive/pattern was simple wood fabrications, and there was no 
>>>> oven,
>>>> rather a big element and a few fans blowing the air down. I think the
>>>> vacuum part was just an industrial blower, as a sucker.
>>>>
>>>> The force required will depend on the temperature, depth of draw 
>>>> required,
>>>> thickness of sheet, resolution of pattern. Although a nice convoluted
>>>> surface can be obtained, the edges always pose a problem, same with
>>>> fibreglass moulds. Trimming them to an exact size, and polishing to 
>>>> hide
>>>> the work, is almost impossible.
>>>>
>>>>
>>>>  
>>>>
>>>>> A home vacuum cleaner arrangement is not really up to the task. 
>>>>> Besides, my
>>>>> earlier experiments with home vacuums lead me to believe a lot of 
>>>>> air FLOW
>>>>> is essential to avoid toasting the motors.
>>>>>   
>>>>
>>>>
>>>>
>>>>
>>>> maybe a powerful blower and a venturi will be better??
>>>>
>>>> Regards
>>>> Roland Jollivet
>>>>
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