Re: [CAD_CAM_EDM_DRO] Re: Materials for machines. Was MDF for machines

Tom,

Doesn't Delrin have a very high thermal expansion rate? Might not be a
problem, except sealing around the edges. I've seen some things made with
plastic sheets bulge and deform when one part got a little warmer than
another. Might not be a problem, but I would at least consider it.
Signmakers use white pvc sheets a lot, sold under different names. A half
inch sheet of pvc that signmakers use would be a very versatile and
available material for things like router tables. I have used this stuff for
signs I have made, but I forget the names it is sold under. Don't remember
much expasion problems with pvc. Signmakers?

Tom E.

----- Original Message -----
From: Tom Murray <thomasm923@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Wednesday, June 27, 2001 9:38 PM
Subject: [CAD_CAM_EDM_DRO] Re: Materials for machines. Was MDF for machines


> --- In CAD_CAM_EDM_DRO@y..., ballendo@y... wrote:
> > P.P.S. Another possibility is a "chemical grade" sheet plastic.
> Don't
> > use plain polycarbonate(Lexan, Tuffek are two trade names), as the
> > hydrocarbons of the dielectric will weaken and "craze" it...
> Acrylic
> > might also work, and PVC sheet seems a (good)possible alternative.
> >
> > I suspect that the plastic alternative panels will not have
> > the "stiffness" of the trespa or phenolic, so consider this when
> you
> > are deciding.
>
> PVC is a pretty good choice in regards to chemical resistance,
> however a good plastic to consider is Delrin (also known as Acetal).
> From what I've seen it is pretty stiff and it is resistant to a lot
> of chemicals. Another plus - it is relatively inexpensive. I can
> check on it's resistance to dielectric fluid if someone can tell me
> what is in it.
>
> -Tom Murray
>
>
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