Re[2]: First light...Sort of

At 05:09 PM 09/17/1999 -0600, Tesla List wrote:
>Original Poster: Aric_C_Rothman-at-email.whirlpool-dot-com 

>     Since I made an enclosure for the RQ gap that includes a 1 HP vacuum 
>     motor for cooling/quenching, I'm thinking about building a new RQ gap 
>     with the same form factor.  I think I erred in using the same tube as 
>     my secondary coil form as support for the RQ gap.  It's the 
>     thin-walled, sickly-green PVC pipe used for low-pressure waste lines.  
>     Has anyone had similar problems using the thick PVC?  Would the 
>     chloronated PVC be a better choice.  What bonding method should be 
>     used to join the Cu pipes to the PVC?  I used JB Weld (epoxy) followed 
>     by Pop Rivets.


Just a suggestion: 

I would not epoxy the copper pipe electrodes in place when you build
your next gap unit. You can just use 1/4" x 3/4" brass or steel machine
screws to hold each pipe. It will be a real pain to clean the electrodes
if they are glued down. I can remove all 12 pipes from my gap unit, clean
them and re-install them in about an hour. It will take you several times
longer than that to use emory cloth, emory boards, or thin sandpaper
to clean the gaps in-place if they are epoxied down.

My gap unit is built using a 6" diameter SDR-35 PVC sewer drain pipe,
the "green stuff" (made by Crestline). This type of pipe will not melt down.
In fact, I have two of these units, one currently in use, and a spare. 
This pipe was a 10" length section leftover from my 6" secondary. It
is thick-walled. You will not be able to find this type of pipe at a hardware
store. Go check the yellow pages for plumbing supply outfits in your area.

I would not even epoxy the spark shield in place either - it will just
get in your way when you clean the pipes. You can use small self-
tapping screws to hold it in, but make sure the screws are at the very
top and bottom of the gap unit, and far enough away from the gap 
electrodes, otherwise they will arc to the screw-points and create a
carbon track, which will short out the entire unit. I used a piece of HDPE
plastic, leftover from my primary supports, for the spark shield. It works

Good luck on your next gap unit and coil resurrection.