Re: Conductive Black UHMW

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

Original poster: "Harold Weiss" <hweiss-at-new.rr-dot-com> 

Hi Scott,

Yes it was $900.  $500 for the 3/4"X10'X4' sheet and $350 for the
1/2"X10'X4' sheet plus tax.  The first measurement I made was 500 ohms
across 3/4", but the battery indicator was on on the meter and I don't trust
that reading.  The second reading was across 2' of it and and that came to
1.3 ohms, still on the same battery.  With the LED at half brightness, I
would say that it's low and somewhere in the under 40 ohm area.  I was
planning on getting 3 coils built out of it.  I had only two colors to
choose from, white or black.  I chose black, as the 3rd coil needed to be in
camoflage and black was the closest color.  I was concerned about the
possibility that the black might break down due to carbon, but was
unprepared for what I found.  I did have to cut a little over 2' off the
sheets to get them in my van, so they're about 8' now.  The dealer was
Midland Plastics.  Send me an address offlist and I'll send you a scrap.  As
for the brush application, I have a dead 20A variac that vaporised two
windings due to overtravel and the brush is junk also, so it would make a
fine lab rat.  Would be cool if it works.

David E Weiss



 > Original poster: "Scott Hanson" <huil888-at-surfside-dot-net>
 >
 > David -
 >
 > Was there a misplaced decimal point in your last posting ($900 worth of
UHMW
 > polyethylene)??? It seems, well, a bit incredible to spend this much money
 > on what sounds like a huge quantity of plastic and not even know what it
was
 > you were buying.
 >
 > Nevertheless, moderately conductive (or static-dissipative) UHMW
 > polyethylene sounds interesting, and I may have some applications for it
in
 > assembly fixtures for ESD-sensitive electronic modules. Who was the
 > distributor from which you obtained this material, who is the manufacturer
 > of the material, and what was the material designation or part number?
 >
 > As for using the material for variac brushes, I'm afraid you will find
that
 > your UHMW polyethylene material is useless. Although it may have enough
 > conductivity to carry a few tens of milliamperes and illuminate a LED, I
 > guarantee it will not carry amperes. Additionally, the melting point and
 > heat deflection temperatures of this material are so low that the brush
will
 > simply deform and melt away under the heat generated.
 >
 > Would it be possible to send me a small sample of this material for some
 > measurements of bulk and surface resistivity? I'd be happy to pay for all
 > shipping and packaging costs, or even to send you a small pre-addressed,
 > postage-paid box to make it super easy.
 >
 > Regards,
 > Scott Hanson