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RE: multiple gap question

My comments interspersed:

>Original Poster: Parpp807-at-aol-dot-com 
>
>In a message dated 2/11/00 2:33:18 AM Central Standard Time,
tesla-at-pupman-dot-com 
>
>
><<  Mine were gapped at about 0.03", I used a feeler gauge to verify that
> all segments were parallel to one another.  Are yours reasonably parallel?
>>
>
>Hi Gary,
>What's "reasonably parallel?" 

I can't put a number on it.  I inserted the feeler gauge between one end of
each pair and noted the "snugness", then did the same at the other end,
making adjustments to make them similar.  Obviously I had to add new pipes
only after existing ones had been adjusted.  I think the suggestions to use
a predetermined number of paper sheets or other sheet stock would be a
better idea, as it allow the gap over the entire width to be set, rather
than the feeler gauge being wide enough only to set one end.

>That's part of my problem and I am wondering if 
>anyone has developed a particular technique for spacing the couplings? I
have 
>mine mounted on 8-32 screws and fixed with nuts so I can adjust the
vertical 
>height. They look like the olive on the end of a toothpick. :-)) 
>The toothpicks...uh screws pass thru 1/4-inch thick acrylic with a slot cut

>into it so the screws can slide horizontally. So I have horizontal and 
>vertical freedom of travel and adjustment. A nut and washer on top of the 
>plastic and under the coupling enable the whole toothpick to be locked in
place. 
>Brilliant, huh? The big  flaw is that as soon as you tighten down on the
lock nuts it 
>changes the gap settings. Lucky if I can guesstimate within +/- 5/1000ths. 
>I cut up a Tropicana OJ jug for shims to help get a little more uniformity.
>Any suggestions---please? 

I think your problem is that it sounds like the screws go through both sides
of the pipes, and when you tighten the nuts, it squeezes the round pipes
into an oval shape, messing up the gap setting.  I used brass screws with
the heads soldered to the inside of the pipes.  This way the roundness of
the pipes is unaffected by tightening, and the screws won't turn as you
tighten the nuts on the far side of the acrylic support.

>The sparks are all off of the circular face.
>None are seen to come from the cylinder walls. I have been able to set the 
gap at 0.028 - 0.030. 

Have you checked the uniformity along the length of the gaps _after_  you
set them?  I'm not sure I understand "circular face".  I assume you mean
they arc only at the ends of the gap where the spacing is presumably
narrower, not _all_  around the circumference of the ends of the pipes?

>The mmc is at 0.011 uF. Not even a gap of 0.018-0.020 will fill a 0.022 uF
mmc. 

You mean to say that with a _single_ .018-.020 gap, it won't break down when
charging a .022uF cap with a 15/60 NST?  I use a 15/60 with a .02uF cap and
it runs quite nicely with a 0.34" (not 0.034") gap.  Something is wrong, and
it's not the gap.

>Happy day,
>Ralph Zekelman

Regards, Gary Lau
Waltham, MA USA