[MakeLV] anyone have access to a vacuform machine? I need 4 - 1/2 spheres, either marble or paintball size. (whatever)

[Joe Dunfee]

I have a small hobby vacuum former that can handle 11x17" 
sheets.  The plastic is heated in your home oven, and a shop-vac used 
to provide the suction.  But, I live in the Lancaster area, and no 
work in York, so it will be rare for me to come up your 
way.  Although, I have to be in Allentown to attend a training class 
the last two weeks in January, and will try to pay a visit.

I have read about model airplane hobbyist and puppeteers using a 
technique to pull the heated plastic over a mold without a 
vacuum.  The plastic is held in a frame of some sort, by either 
clamping or even taping the plastic to it. The plastic is heated by 
holding it under a heat lamp until it sags a bit.  Then, pull the 
plastic over your positive mold.

If you need a totally smooth finish such as for a window,  there is a 
technique used in industry for making the plastic skylights. I 
adapted the technique when I needed a large egg shape for a hatching 
dinosaur puppet.  I cut an opening in a strong cardboard box in the 
profile of the egg. Then, cut another hole in the side for my 
shop-vac nozzle.  I think I simply taped the thin polyethylene foam I 
used to the box.  I don't recall how I heated it. I may have simply 
put the entire box in the oven to slowly soften the foam (foam takes 
a LONG time to heat since it tends to insulate the interior of the 
foam).  Of course, you have to be very careful to control your 
suction.  You must also hold that suction until the plastic cools. It 
was not as hard as it sounds, since the plastic is not totally limp, 
and the more it stretches the more it resists being stretched. A 
second smaller hole on the side of the box,  allows you to control 
the suction by how much you cover the hole with your hand.


Joe Dunfee  joe at dunfee.com
Gordonville, Pennsylvania, U.S.A.