Re: anti-static device

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Commercial hemispheres are made by putting a panel with a circular hole
over a box. You hook up a vacuum source to the box (you don't need much).
Heat the plastic (radiant heaters in a rectangular/square panel are
common.. looks a lot like a bathroom heater or an electric oven). Turn on
the vacuum... 


Process controls are everything on this... Don't go trying to make 4 foot
hemispheres in 1/2" thick plastic without expecting a LOT of scrap.  There
is a lot of art in the process... how hot, how much vacuum, etc.  You are,
after all, stretching the plastic.

The other thing is that the vacuum has to be strong enough that it
dominates the forces.  If you let gravity have its way, you'll get
parabolic shapes.

For what it's worth, the machine I saw doing this actually sucked UP (the
heater was a flat (perforated) plate on which the plastic sat.

Essentially, this is a specialized case of vacuforming, about which you can
purchase books from Lindsay, and, I daresay, find a lot on the web.

Tesla list wrote:
> 
> Original poster: "David Thomson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>
> 
> Hi Robert,
> 
> Thanks for the heat lamp suggestion.  I'll keep that in mind for a later
> project.  It occurred to me that Plexiglas would make excellent conical
> forms.  All I need to do is make a wood form, cut the Plexiglas to a
> template, then soften it over the wood form.
> 
> Explain a little better how domes can be made.  Plexiglas welds nicely with
> the right chemicals.  I could make two domes and then fasten them together
> for a sphere, coat the sphere with copper foil or gold leaf, then coat it
> with resin.  That would make an awesome top load.  I doubt if I'll have time
> to make this one, though.  I've already got a full plate of experiments
> lined up.
> 
> Dave
> 
> -----Original Message-----
> From: Tesla list [mailto:tesla-at-pupman-dot-com]
> Sent: Monday, March 04, 2002 9:04 AM
> To: tesla-at-pupman-dot-com
> Subject: Re: anti-static device
> 
> Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <rheidlebaugh-at-zialink-dot-com>
> 
> Dave: years past we used 4 heat lamps and a wood plate covered with a cotton
> white cloth to soften and form plexiglas. The heat lamps gave even control
> of the heat. Oven heat was not even enough. If you clamp the plex dowm and
> put air under it you can shape domes, or vacuum pull it into molds.
>   Robert  H
> 
> > From: "Tesla list" <tesla-at-pupman-dot-com>
> > Date: Sun, 03 Mar 2002 19:55:17 -0700
> > To: tesla-at-pupman-dot-com
> > Subject: RE: anti-static device
> > Resent-From: tesla-at-pupman-dot-com
> > Resent-Date: Sun, 3 Mar 2002 20:00:02 -0700
> >
> > Original poster: "David Thomson by way of Terry Fritz
> <twftesla-at-qwest-dot-net>"
> > <dave-at-volantis-dot-org>
> >
> > Hi Tim,
> >
> > Because of your post, I started brainstorming on this.  I did some
> research
> > on Plexiglas and found that it can be softened and formed.  I have found
> > that I can wind very nice coils between two flat smooth surfaces if there
> is
> > no glue or resin present.  With glue or resin between the sheets the coil
> > becomes lopsided and filled with air bubbles.  So I'm going to wind a coil
> > between two sheets of Plexiglas and then bake them in a 250 degree F oven
> > for about 4 or 5 hours.  I'll sandwich the two Plexiglas pieces and coil
> > between two pieces of plywood and place about 100 lbs of bricks on top.
> > I'll monitor the space between the two sheets of Plexiglas, and when they
> > touch I'll remove the coil from the oven.
> >
> > Coils made in this manner should work well for the anti-static device.  A
> > metal sleeve can be built into the core of the Plexiglas before starting
> the
> > winding to allow for the contact with the rod.  I have the Plexiglas
> sheets
> > already cut.  Once I find some sleeves, I'll get started and try this out.
> > Even if the device doesn't work, I'll have two nice coils to work with.
> >
> > Dave
> >
> > -----Original Message-----
> > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > Sent: Sunday, March 03, 2002 3:30 PM
> > To: tesla-at-pupman-dot-com
> > Subject: Re: anti-static device
> >
> >
> > Original poster: "tim slayter by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> > <arky-at-uswest-dot-net>
> >
> > Hi Dave,
> >
> > That was the only two words that described it on the Wardenclyffe Project
> > Archive web page.
> msnip...