Re: [PSUBS-MAILIST] Acrylic Molds

["Dan H." <JMachine@adelphia.net>]

Mike,

As you might imagine, it gets soft and sags because of it's thermal
expansion but you just tighten it a little.  Of course, if you heat it to
hot it'll end up in a puddle on the floor.  You only want it to get hot
enough to heat the plastic.  You don't want the rod to get red hot.  You
don't want to melt the underside of the plastic before the heat conducts
through to the top and you don't want to cook the welder either.  My welder
is a big but I used it on the lowest current setting and also used a long
rod to add resistance.

  I'm sure you could find a nicrome strip wire from an old electric space
heater if you have doubts about a carbon steal rod.  Any wire will grow when
it gets hot though.  I just tightened in a little.  Do some experimenting.
As I said, the Plexiglas I bent was only quarter inch thick.  I'm no expert
but it worked for my needs.

Dan H.
----- Original Message -----
From: "Michael B Holt" <tlohm@juno.com>
To: <personal_submersibles@psubs.org>
Sent: Thursday, January 09, 2003 8:00 AM
Subject: Re: [PSUBS-MAILIST] Acrylic Molds


> On Wed, 8 Jan 2003 19:28:30 -0500 "Dan H." writes:
> >
> >  I ran a horizontal steel rod a few  inches
> >under the sheet and hooked the ends of the rod to a welder on really
> >low amperage.  The rod got hot and heated the Plexiglas directly above
> it
> >in a straight line.  It got pliable above the hot rod.
>
> What is the effect on the strength of the material of heating and
> cooling in a different shape?
>
>
>
>
> Mike H.
>
>
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