Subject: Rotary gaps
Date: Thu, 20 Apr 1995 15:11:30 -0400
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I am planning to build a rotary gap and would appreciate any suggestions or
comments from those who have already done this.
I am planning to use a 12.0" diameter nylon disc probably 3/8" or 1/2" thick.
If I remember what I've read, my first choice for electrodes should be
tungsten, then brass then copper. Is this correct? I can only find tungsten
in 5/16" dia. I think it is available in up to 3/8" but I haven't found any
yet. I was thinking that I wanted about 1/2" dia. electrodes. Any comment?
I will use set screws in from the outside to hold the electrodes in place.
I know I want to make the two stationary electrodes adjustable so I can vary
the gap. If using this in series with a quenched gap what do you set the
gaps for? Something like .050"?
This gap will be asynchronous. I want to be able to control the speed so it
will fire 4 or 5 times during each half cycle (I have a transformer that will
supply plenty of current so I might as well take advantage of it) - does this
make sense? If I use 8 electrodes, I need to run at up to 3600 to 4000 RPM.
I would like to use a universal DC motor so I can control the speed with a
variac and a full wave bridge. Can a small sewing machine motor handle this?
The bearings in the motor may not support it. How about mounting the disc
on a separate shaft with bearings on each side and driving it with a belt?
I would think it needs to be a sturdy construction (so the gaps aren't moving
in relation to the disc) so I probably want to build it on a steel frame.
Any comments would be appreciated.
Thanks, Ed Sonderman