Re: Rotary gaps

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 Te> Message-ID: <9504202030.AA17878-at-grendel.objinc-dot-com>
 Te> Newsgroups: tesla.list

 Te> From Esondrmn-at-aol-dot-com Thu Apr 20 14:14 MDT 1995
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 Te> (5.65c/IDA-1.4.4 for <tesla-at-grendel.objinc-dot-com>); Thu, 20 Apr 1995
 Te> 13:11:36 -0600
 Te> Date: Thu, 20 Apr 1995 15:11:30 -0400
 Te> From: Esondrmn-at-aol-dot-com
 Te> To: tesla-at-grendel.objinc-dot-com
 Te> Subject: Rotary gaps

 Te> I am planning to build a rotary gap and would appreciate any
 Te> suggestions or comments from those who have already done this.

 Te> I am planning to use a 12.0" diameter nylon disc probably 3/8" or 1/2"
 Te> thick. If I remember what I've read, my first choice for electrodes
 Te> should be tungsten, then brass then copper.  Is this correct?  I can
 Te> only find tungsten in 5/16" dia.  I think it is available in up to 3/8"
 Te> but I haven't found any yet.  I was thinking that I wanted about 1/2"
 Te> dia. electrodes.  Any comment? I will use set screws in from the
 Te> outside to hold the electrodes in place. I know I want to make the two
 Te> stationary electrodes adjustable so I can vary the gap.  If using this
 Te> in series with a quenched gap what do you set the gaps for?  Something
 Te> like .050"? 
 Te> This gap will be asynchronous.  I want to be able to control the speed
 Te> so it will fire 4 or 5 times during each half cycle (I have a
 Te> transformer that will supply plenty of current so I might as well take
 Te> advantage of it) - does this make sense?  If I use 8 electrodes, I need
 Te> to run at up to 3600 to 4000 RPM. I would like to use a universal DC
 Te> motor so I can control the speed with a variac and a full wave bridge. 
 Te> Can a small sewing machine motor handle this? The bearings in the
 Te> motor may not support it.  How about mounting the disc on a separate
 Te> shaft with bearings on each side and driving it with a belt? 
 Te> I would think it needs to be a sturdy construction (so the gaps aren't
 Te> moving in relation to the disc) so I probably want to build it on a
 Te> steel frame. 
 Te> Any comments would be appreciated.

 Te> Thanks,  Ed Sonderman

 MG> Ed, First I would recommend building the disk out of Lexan, it will
 MG> not shatter under any circumstances, in my rotary I used 3/8 thick
 MG> clear Lexan 8" in diameter with 8 electrodes and I spin it at 5000 rpm.
 MG> I use 1/4-20 theaded rod on the disk with a stainless steel acorn (cap)
 MG> nuts on each end for each electrode. It has been my experience that
 MG> "rounded" electrodes quench much better than flat ones. The stationary
 MG> electrodes are 3/8" diameter Tungsten mig welding contacts that are
 MG> mounted on heat sinks, each gap is set at about .020". 
 MG> My disk is mounted right on the motor shaft (1/4") with a hub I had
 MG> specially machined to insure it was true. The entire gap system is
 MG> mounted in a box made out of 3/4" plywood for safety and the box is
 MG> pressurized with a blower. 
 MG>  I run an input of 5KW with a primary capacitor of .09 ufd and these
 MG> electrodes have no problem standing up at this power level.

 MG> Mark Graalman

     compuserve 71612,1234

... Alias, Mark the spark
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