Re: spark gap
> I cut a bunch of 1x3 inch paper strips on a paper cutter. I used the "HP
> Bright White" inkjet paper that is 0.0044 inches thick. I set each
> cylinder down on the wood base with epoxy between the cylinders and the
> wood. I used a few slips of the paper between the cylinder to space them
> apart. Once the epoxy has set, I simply pull out the slips of paper
> leaving a perfectly gaped (parallel) space between the pipe section. See:
> This gap is sort of disposable but mine has lasted for years with an
> occasional forcing things in the gaps to clear shorts. It really does arc
> in the center sections and not at the pipe ends. It can run 1kW for a
> while and much more with fan cooling. Finn used it for his coil with much
> better forced cooling as shown at:
> See my experimental gap at:
> I just used one, two, three,... slips of paper between each section as a
> simple test part. The paper slips were left in until the epoxy set and
> then removed to leave a perfectly spaced and parallel surface for arcing.
> It took about 30 minutes to make...
> I would be happy to send it to you if you shoot me your snail mail address.
> Then you could compare it and see what's up with all this...
> There is a possibility that the taper a pipe cutter leaves and the sanding
> of the edges is not only "nice", but extremely critical which may account
> for your problems...
Are you saying that you can run for "some time" (seconds, minutes?)
with the pipes staying cool enough that the epoxy doesn't
disintegrate??? I remember looking at that gap before, thinking it was
a neat idea, but didn't copy because of concern about overheating the