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Subject: Re: [Homebrew_PCBs] Re: vacuum hold-down for exposure box

From: Piers Goodhew <piers@...>
Date: 2009-03-23

Well, this thread that wont die gets you thinking:

My first thought was:

glass
fabric
board (incl. artwork and film)
base

to evenly remove the air between the board and the glass. But, uh, the
UV might not go thru the fabric so evenly ...

Board and glass need to be close to the same size to prevent stress,
with a flexible seal around them.

Then I thought, you could replace the glass with clear vinyl, which
will just flow around the board and not bow

Then I thought, make the ∗bottom∗ vinyl and eveything is evenly
pressed UP onto the glass with no stresses at all, and you still get
that nice even glass.

Then (for the less frequent exposer) why not stick the whole sandwich
into one of those vacuum "space bags" you use to shrink your winter
clothes away with.

(Myself, I think I'll keep on improving my TT skills)

PG



On 23/03/2009, at 1:50 PM, DJ Delorie wrote:

>
> Simao Cardoso <simaocardoso@...> writes:
> > Hi, i can't really see a point in using vacuum in two rigid flat
> > surfaces.
>
> I've found that they're not quite "flat" enough.
>
>