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About Toy Canister Vacuum
QUESTION: This isn't really related to scale models, but the techniques are the
same,
and I'm hoping that some of you vacuum-forming gurus can help me out...
I'm trying to reproduce a poor-man's version of the clear blister
packaging
for a toy car by vacuum forming clear vinyl sheet over a plaster mold.
Here's some pictures...
The original blister package with the toy:
http://albums.photopoint.com/j/View?u=1590248&a=12179464&p=44530461&S...
My Future-coated plaster form:
http://albums.photopoint.com/j/View?u=1590248&a=12179464&p=44530456&S...
Instead of the customary sheet styrene, I'm using clear vinyl sheet as I
was
told that this is what the original material is. I forget the exact
thickness
of the sheet, but I believe it's around 0.010" (about 1/3-1/2 the
thickness
of a credit card).
My homemade vacuum table and frame for holding the plastic sheet:
http://albums.photopoint.com/j/View?u=1590248&a=12179464&p=44530454&S...
http://albums.photopoint.com/j/View?u=1590248&a=12179464&p=44530455&S...
For a heat source, I'm using my kitchen oven set to 300 degrees F. For
the vacuum pump,
I use the household (3 peak horsepower) canister vac.
Now, here's my problem.
As the vacuum draws the warm vinyl over the form, the vinyl folds in on
itself at the
sharper corners of the mold, creating creases down the sides of the
part. Shown in
this picture:
http://albums.photopoint.com/j/View?u=1590248&a=12179464&p=44530459&S...
How do I prevent this from happening? I think that this problem is a
result of the
master being too tall as well as the lack of undercut along the bottom
edges of the
form. Unfortunately, I can't add undercuts as I want a smooth, flat lip
of
plastic around the bottom edge of the blister... I've also considered
using female
molds, but a little experimentation showed that my vacuum doesn't have
enough suction
for that technique.
I'm all out of ideas, (and experience, for that matter)
Need help!!!
Thanks ahead of time,
ANSWER: your problem is called webbing try putting a small block next to the mold
that will take up the extra plastic. another solution is to try to form at a
lower temp.
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