Re: Ball bearings

I have made very serviceable and clean-looking safety gaps using large
carbon-steel bearing balls (.75" & 1") brazed onto short segments (4") of
1/2" dia rigid copper pipe. Slightly flare the end of the pipe using a
flaring tool to create a ball-seat, then silver-braze the ball in place. I
also brazed a brass nut in the opposite end of the tube to allow easy
electrical connection via a solder lug. Each electrode assembly supported
on small Delrin pedestals, cross-drilled to allow a sliding fit of the
copper pipe for gap adjustment. After adjustment, the pipe is locked into
the pedestal with a small set screw. After final clean-up and polishing,
spray the pipe and ball with polyurethane to prevent corrosion of the ball
and tarnishing of the copper. The first time the gap fires it will vaporize
a small spot of polyurethane at the end of the ball. I use a 3-ball gap set
up in a "tee" configuration at both input and output sides of an RCR filter
network per the circuit suggested by Terry Fritz.
I'll post some pictures of my filter setup and these safety gaps on my
website at www.geocities-dot-com:80/CapeCanaveral/Lab/9787


Tesla List <tesla-at-pupman-dot-com> on 06/16/99 10:54:41 AM

To:   tesla-at-pupman-dot-com
cc:    (bcc: Scott L Hanson)

Subject:  Ball bearings

Original Poster: "E.Seekins" <seeked-at-sover-dot-net>

Terry Fritz <twftesla-at-uswest-dot-net wrote:
>I may end up using ball bearing electrodes to get a much
>more stable firing voltage for the safety gaps.  I assume cobalt drill
>will cut through ball bearings to mount the shafts that hold them?...

Hi Terry, etc.
You're probably already aware of these, but just in case:
You can get "tooling balls" in a myriad of sizes already mounted to various
shafts with threaded ends (and some of the shafts do have a pretty stylish
faceted look to add visual impact (!)).
Also, "metrology balls" (used for measuring tapped holes with a cmm, etc)
are similar.
I was surprised at how cheap they were last time I looked them up in a
catalog like MSC's (mother of all catalogs).
MSC or Carr Lane probably even carry balls with tapped holes.
Then again, you do have a drill press....  :-)