Re: coil form material (fwd) (ABS) (fwd)
---------- Forwarded message ----------
Date: Wed, 29 Apr 1998 12:28:01 -0700
From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: coil form material (fwd) (ABS)
> ---------- Forwarded message ----------
> Date: Wed, 29 Apr 1998 02:16:58 -0700
> From: Roger Drosd <roger-at-gcisnow-dot-com>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: coil form material
> I would like to know the (dis)advantages of using ABS
> pipe for a coil form. Better or worse than PVC, carboard, acrylic?
You'll note that ABS pipe (commonly called DWV (drain, waste, vent) pipe)
is actually a foam composite to reduce weight (and cost, because you pay
for plastic by the pound). It has an outer layer of solid ABS, a cellular
(foam) layer in the middle, and another sold ABS layer on the inside. From
a loss standpoint this is probably pretty good (air has a real low loss
tangent, that's why heliax and foamed dielectric coax is made for VHF and
UHF use). However, from a breakdown voltage standpoint it is bad: air is a
lot worse than almost any plastic.
ABS DWV pipe is also not a very good structural material, although I don't
know if this would be relevant for use as a coil form. It isn't designed to
take any real pressure (a few psi, max), given its intended use.
Finally, I would be highly suspicious of any black plastic for HV use. How
do they get it black? By using a black filler, usually carbon. I tried to
build an electrostatic generator using ABS pipe to transport charged dust
and it never worked very well because the charge leaked off through the
pipe. Changed to PVC and it worked like a charm, albeit at greatly
increased parts cost....