Homebrew PCBs

I form 060-090 and 125 Arcylic parts using a toaster oven
and a shop vac. It's not hard to do at all. These aren't
quite 48x96 sized parts but as you get bigger its more to
do with the amount of vacuum you can pull. Also depends
on the shape and detail of the part you want to make.

You don't always need to do vacuum molding if you have
simple but larger parts. You can manually pull the hot 
acrylic over the mold or used diffused compressed air.
The biggest thing I have seen being molded without vacuum
forming was a canopy for an 2 seat airplane. It used a full sheet
of 250 arcylic. The guy came up with a pretty clever way 
of doing it too. He built a male mold using steel and a
layer of concrete about 1 inch thick. The concrete being
the outer layer with a smooth finish etc. The steel was
just for support to get it off the ground. They then heated
the concrete from the bottom side with a propane tiger torch.
When the concete was evenly heated they just waited until 
it was at the right temp, and simply laid the sheet on top
and walked away. The hot concrete would slowly heat the 
sheet and gravity did the rest. This sounds crude but the
result is optically perfect parts.

Dave



-----Original Message-----
From: Homebrew_PCBs@yahoogroups.com
[mailto:Homebrew_PCBs@yahoogroups.com]On Behalf Of twb8899
Sent: January 3, 2007 8:06 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: OT: molded plastic enclosures


Stefan,

The .125" thick ABS vacuum forms without much trouble. Thicker
plastics will also work but it starts getting difficult. Thicker
sheets may need top and bottom heaters and a very powerful vacuum
pump. I've seen .250" ABS vacuum formed at a fabricators plant. It was
a 48" x 96" sheet. The machine was huge and so was their electric
bill!!  I'll stay with the thinner materials...  lol

Tom



--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@...> wrote:
>
> On Tue, 02 Jan 2007 18:12:50 +0100, twb8899 <twb8899@...> wrote:
> 
> > I use vacuum formed parts in my product line. The plastic parts are
> > made from .040" or .060" high impact polystyrene and .060" and .125"
> > ABS. My vacuum forming machines are made by Diacro and Q-Vac. I
> > purchase the materials as I need them so the moisture usually isn't a
> > problem. The Diacro machine is smaller but I have formed .125" ABS
> > parts 6" deep with this machine. My molds are made from hardwood and
> > sometimes I solder pieces of circuit board laminate together to make
> > the shape needed. Most of the molds I use are positive molds but I
> > almost always use negative (cavity) molds for the deep parts.
> 
> 
> I did not know plastic that thick can still be vacuum formed, good
to know!
> 
> ST
>




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