From: Julian Green [SMTP:julian-at-kbss.bt.co.uk]
Sent: Tuesday, June 30, 1998 9:23 AM
Subject: Re: RSG Question
> Does anyone have any design suggestions for building a
> non-synchro gap for a fairly high powered system at a low cost? I'm in
> the process of building 2 coils, one a smaller 1 kw system with a static
> gap, and I'm also winding a 6 inch secondary with 14 awg for some future
> system, driven by a pole xfmr-- I won't probably be building the rotary
> for another year, but I imagine that if I'm in the same financial straits
> that I'm in now I won't want to spend a lot of money on custom tungsten
> contacts.... Will carriage bolts work just as well? Do the contacts have
> to be rounded?
Why not try mine? It took a couple of evenings to make.
Its bassed on a washing machine motor. The brush type with field
winding wired in series with armature windings. It goes at 9000 RPM
on full voltage.
The rotor is made of fiberglass PCB copper clad board with two 3mm
steel bolts on the outer edge as electrodes. The fixed electrodes
were made from 6" nails, but they burnt away too quickly (30 seconds)
I now have 1/8" tungsten. The rotating electrodes although made of
steel do not burn. The air flow must keep them cool.
The copper clad board has been made into a disk by drilling a hole in the
center of a 7" square piece of copper clad. Mounting on the
motorshaft with a 3mm screw. The motor is then used to rotate the rough
cut board and an angle grinder to gut away the square edges. Use a
variac to keep the motor speed down while you do this. Pieces on board
will fly off. After a short time and a lot of dust you have a perfectly
round and balanced disk.
The copper in the center has been etched away to insulate the motor
from the HV.
Two tungsten electrodes are held in position over the spinning disk
and align with the 3mm screws mounted on the disk. The tungsten
electrode supports have been mounted on plexi glass that has been
screwed to the motor housing.
The motor can then be mounted in a wooden frame and should have a
guard around the rotating disk in case something breaks. When
operating do not allow anyone to stand on axis with the disk.
If it breaks the pieces come flying off at around 400 feet per
second. If the wheel becomes unbalanced then watch out.
Vibrations will cause the rotating disk to flex and electrodes to
collide. (That is why my disk is no longer round)
This rotary is nothing special, but its cheep and easy to build.
Have a look at Mike Harrisons web page and the UK teslathon pictures
there is a picture of it there.