Re: [TCML] my recommendation for a SRSG motor arbor

["David Rieben" <drieben@xxxxxxxxxxx>]

Jon,

I had originally fabricated a reb fiberglass disc and IIRC,
I turned the original fiberglass disc on the hub and trimmed
the outer periphery of the disc while it was attached to the
hub. This insured the finished disc was true centered to the
hub.You are quite correct that it is very difficult to make
home-machined parts true w/out access to a drill press,
band saw, table saw, end mill, ect. I had a heck of a time
myself and could not get my RSG as precision as I would
have liked. As a matter of fact, I ended up having the
new G-10 disc machined by a professional machinist but
I still "messed up" in having him use the original red fiber-
glass pattern for drilling the holes for the 8 flying electrodes.
The resultant holes were of course truly perpendicular to
the surface of the disc and that's the main reason that I
had that part done by a professional. Trying to drill per-
fectly perpendicular holes with a hand drill is an exercise
of pure futility and the holes MUST be perpendicular to
insure proper placement and alignment of the flying electrodes
at their presentations to the stationary electrodes.
But they were still not quite in perfect equidistance from the center
and there ended up being about a 1/16" tolerance in their distance
from the center point of the disc. That's far too much play IMHO
and while some of the 3/8" diamtered flying electrodes will line
up pretty centered with the 1/2" diametered stationary electrodes,
others will line up off-centered and the outer radius of the smaller
flying electrode may even slightly overlap the outer radius of the
of the larger diamtered stationary electrode, relative to the centerline
of the disc and rotor arbor. Is that as clear as mud? :^) In other
words, some of the flying electrodes are around 1/16" farther from
the centerof the disc than some of the others.
But it was my fault because I had them follow the hole placement
pattern of my old disc and that was the best accuracy that I was
able to obtain with my "stoneage" machining facilities. It is still
close enough that it does operate properly now though
and doesn't vibrate too badly and I can get flying/stationary
electrode seperation at each presentation to about .05" w/out
risk of electrode crash. That should give me a total gap spacing
of less than .25". BTW, I had been able to get each of the flying
electrodes'  45 degree arc seperation from their neighbor flying electrode
pretty close by use of marking lines in a "pie slice" pattern with a 
carpenter's
square.

David Rieben


----- Original Message ----- 
From: "Jon Danniken" <danniken@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Cc: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
Sent: Thursday, November 29, 2007 10:04 AM
Subject: Re: [TCML] my recommendation for a SRSG motor arbor


> ----- Original Message ----- 
> From: "David Rieben"
> [snip]
> >  I simply drilled out 3
> > matching 1/4"  holes in my G-10 rotary disc to match the
> > tapped holes on the bushing and screwed the disc to the
> > bushing face via these holes with proper size/length bolts
> > and lock washers.
>
> David, how did you ensure that the center of the bushing was concentric 
> with the center of your disc?
>
> I'm using a shaft arbor right now, which means a hole in the center of the 
> disk (pretty easy), but I can't for the life of me figure out how to 
> layout the holes on the disk to correspond with a bushing hole pattern 
> without having access to a mill or an X-Y table. .
>
> Jon
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla 

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