Re: SRSG machineing

[Terry Fritz <twftesla-at-uswest-dot-net>]

Hi Chris,

At 05:31 PM 8/4/00 +0000, you wrote:

>I have finally gotten ready to make the SRSG for Sam. I have a nice Baldor 
>Single phase motor of the following spec.
>
>Cat No. L3353
>Spec. 33-850-934
>Frame. 42
>Ser. W0300
>H.P. 1/8  TE

That is a little lower than the 1/4 HP I use but I think it will still work
fine.  I think John Freau had a little trouble with low HP motors but I
think they were far smaller.

>Volts 115/208-230
>Amps. 3.1/1.6-1.55
>R.P.M. 1725
>HZ 60
>PH 1
>Ser. F. 1.40
>Class 8
>Full Load Eff. 47% PF. 55%
>Rating 40C AMB-CONT
>SFA 3.6/1.9-1.8
>
>I wish to make a SRSG for use with multiple NST's and eventually (within 2 
>months) a 10kVA PIG.
>
>For conversion, is it 2 or 4 flats? Is .75" wide the correct size for the 
>flats?

Four flats are a must at 1800RPM.  There have been some 2 flat versions but
that is sort of experimental and you motor may not have the power for this.
  You will have to measure and calculate a bit when you get the motor
apart.  0.75 inch is "close", but not exact.

>Is there a certain spot I should locate the flats to on the Armature?

No, but I try to locate natural 90 degree "landmarks" that may already be
on the rotor to make measuring easier. 

>What should I make the rotor from?

G-10 or LE phenolic is great.  Some say lexan but I kind of worry about the
heat...  The phenolics have all that woven thread in them which really help
"keep it together".  1800 RPM is a pretty sane speed so it should not fail
unless it crashed really bad.

>
>Is a conductive or non conductive rotor best?

I would definitely go with a non-conductive rotor.  You will have to
isolate it somewhere and watch the total mass.  A non-conductive rotor is
very standard if no the "rule".

>I.E. Conductive rotor setup having the electrodes located along the 
>periphery of the rotor pointing out with the gaps happening at either side 
>of the rotor diameter while a non-conductive rotor has the electrodes in 
>axis to the rotation with both posts on the same side of the shaft but 
>opposite sides of the disk. With 4 posts this can be made into dual gaps.

Hmmm, I think putting the electrodes through holes in the face (like simple
bolts) is easier than the edges for those of us with modest tools.  If you
have good machining, then it may not matter much.  I think "you" have
access to machining tools "I" can't even dream of :-)))  I think having the
electrodes on the face makes for a smaller and more "aesthetic package" but
that may be an "opinion".

>
>hmmmm....you could run 2 coils exactly in time from a single gap. Has this 
>ever been done?

The rotor would need two "circuits" and four stator electrodes.  Not a big
deal really if this was something you need.

>
>Could a twin-coil setup have seperate gaps perfectly synced to each other? 
>(Smpte for a Tesla Coil :)....cool)

If your ran two coils on one gap, you could have it no other way :-))

I guess "I" would suggest not making a rotary gap more complicated than it
needs to be.  One "can" think of all kinds of fabulous and complex setups
and great ideas.  However, for a first try, I would just make it as simple
a straight forward and functional as possible.  Once you have made your
first, then you will see all the little subtle things that may bite you if
your try to make it too fancy on your first try.  It is really easy to make
a simple rotary gap but you can easily make it too complex too.  You don't
want to add anymore "things to go wrong" on your first one than needed.
You will have many other great ideas once you have done one and then you
will also know what works and what may not be a good idea in retrospect.

I have actually made many more rotary gaps than I "admit to" :-))  So I
have learned a bit the "hard way".  Make a good solid basic functional
design.  Use a few rock solid simple parts that won't let you down.  Fancy
"cool ideas" have not worked well for me...  Make things really strong.
There is a lot of force, vibration, and tight tolerances that you have to
deal with.  If your going to spend a lot of time and money, you may want to
post the "plans" for review so others can check for those little "gotchas"...

IMHO...

Cheers,

	Terry

>
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>Christopher A. Boden Geek#1
>President / Founder
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