David,
Wow, that's some big KVA control!
I like the boat wheel idea. For the price of a 3/4 bit, a local machinist
may come in the ball park of your budget. It would be easy to do as the
taper will serve as the pilot - no setup, just a slow HD drill press. I
guess you will need to drill and tap some set screws. The mine wheel is
pretty cool "steam punk". 1/4" - 20 uses a #7 drill (I just made a Wysock
rotary with these set screws in stainless) for pig use with .5" Tungsten
electrodes. BTW, I don't think an 8" will offer much mechanical advantage.
The knob looks to define a 7" diameter. You may find a knob at some custom
or big auto parts store for one hand use... a motorcycle handle bar size
clamp or something like that might get you to a greater outside diameter on
the stock 1256D wheel and one hand use.
Jim Mora
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of David Rieben
Sent: Thursday, July 03, 2014 7:09 AM
To: Tesla Coil Mailing List
Subject: [TCML] Bigger Variac Control Wheel
Hi all,
I have been recently trying to secure an economical control wheel to replace
the factory black phenolic control knob wheel on my 4-stacked 1256D
Powerstats in my Green Monster pig coil control panel. Reason being is that
the turning of the combined 4 variacs while smooth, does offer significant
resistance to overcome the friction of turning the rotating guts of 4 large
units. I'm sure the factory 7" outer diamter control wheels that Powerstats
come with are more designed for operating a single variac unit and not
multiple units. (Multiple units are typically operated with a remote control
motorized drive). I can run the variac thru its range simply enough, but to
do so comfortably pretty much requires both hands. So, I'm kind of looking
for something a bit larger, say in the 10" to 13" diameter range, or maybe
just 8" diameter if it had one of those "suicide knob" type handles on the
wheel, like a lathe control wheel, for example. I've spotted a few possible
candidates on eBay but am a little concerned on how well the hub would match
up with my 3/4" solid steel shaft through my variacs. Some of
the boat steering wheels have the tapered 5/8" to 3/4" hub hole and that
would not work for a solid 3/4" shaft. Some of the large valve control
wheels look like a possible fit or if the hub was too small but straight and
untapered, I could simply bore it out to the required 3/4", although finding
a 3/4" standard twist drill bit in my local Home Depot has proven to be
rather illusive. Anyway, I do prefer the manual hand control to motorized
control but would like the find a control wheel that offers a bit more
leverage. Here a couple of eBay candidates that I have found:
http://www.ebay.com/itm/301222411547?_trksid=p2055119.m1438.l2649&ssPageName
=STRK%3AMEBIDX%3AIT and
http://www.ebay.com/itm/121374903703?_trksid=p2055119.m1438.l2649&ssPageName
=STRK%3AMEBIDX%3AIT
Any suggestions from those more mechanically inclined than me (not difficult
at all :-) would be most welcome.
Oh yea, is anyone else having trouble snipping a chosen part of a post when
responding via "reply all" through the new format of this list?
Thanks,
David
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