Jackson Brothers http://www.mainlinegroup.co.uk/jacksonbrothers/
Makes some excellent planetary drives. There are dealers in the USA.

Bill W0IYH

"msg" wrote in message
...
Gary Tait wrote:

msg wrote in news:139f22h91ghhna7
@corp.supernews.com:


I need the form factor for modifications to antenna
rotator assemblies


Do you mean the rotator or the controller?

For the rotator, you can maybe use a standard pot with gearing.
snip

I had considered gearing but the available space and the
necessary additional fabrication was more involved than
the solution I chose.

Here are photos of the modified rotor:

http://www.cybertheque.org/homebrew/...ntennas/rotor/

This rotor is common to a number of makes and models; the controller
that came with it was for the Cornell-Dubilier AR22R, an interrupter
based spring and escapement controller version.

The modifications permit continuous rotation and rely on the
controller to manage limits.

Regards,

Michael
msg _at_ cybertheque _dot_ org

"Alan Nishioka" wrote in message
ups.com...
On Jul 13, 7:12 am, msg wrote:
Please view these photos of a three-turn planetary drive
pot that uses a conventional "stackpot" formfactor
athttp://www.cybertheque.org/homebrew/rcvr/images/antennas/pot.jpg
Resistance = 1K

Interesting. I've never seen a pot like this.

So the turns ratio is determined by the shaft diameter to ball
diameter ratio?
And the wiper arm is connected to the ball carrier?
So this assumes the metal to metal, shaft to ball won't slip, but the
ball will turn in the carrier, causing the carrier to have 1/3 the
rotation of the shaft?

Sorry, this doesn't help you at all...
Alan Nishioka
The ratio, is determined by the shaft diameter, to the internal diameter
of the casing in which the balls sit.
If (for instance), you have a 3mm shaft, and 10mm balls, the casing has to
have an internal diameter of 26mm, and the ratio is 26/3 = 8.66:1. The
drive can be made remarkably good (the same system is used on some micro
focussers for telescopes, which carry significantly more torque than
needed for a pot). Units like the 'Williams optics feathertouch focusser',
use exactly this drive.

Best Wishes

The ratio, is determined by the shaft diameter, to the internal diameter
of the casing in which the balls sit.
If (for instance), you have a 3mm shaft, and 10mm balls, the casing has to
have an internal diameter of 26mm, and the ratio is 26/3 = 8.66:1. The
drive can be made remarkably good (the same system is used on some micro
focussers for telescopes, which carry significantly more torque than
needed for a pot). Units like the 'Williams optics feathertouch focusser',
use exactly this drive.
=================
Sorry ,but I don't understand the above .
If the shaft has a diameter of 3mm and the balls a diameter of 10mm, the
inner diameter of the casing should be 10 + 10 + 3 equals 23 mm

When the shaft makes 1 revolution the balls will make 3/10 revolution .
When the balls make 1 revolution the casing makes 10/23 revolution .
Hence when the shaft makes 1 revolution the casing will make
3/10 * 10/23 equals 3/23 equals 0.13 revolution , hence reduction factor
is 7.7
Please correct me if I made an error.

Frank GM0CSZ / KN6WH

Roger Hamlett wrote:
If (for instance), you have a 3mm shaft, and 10mm balls, the casing has to
have an internal diameter of 26mm, and the ratio is 26/3 = 8.66:1.

I could be missing something, but at first glance I read the radius as
the diameter of the 10mm ball (10mm) plus half the diameter of the 3mm
shaft (1.5mm) and get 23mm internal diameter, ratio of 23:3 or 7.66:1.

Just in case this turns out to be a corecktion I've included speling
erors to comply with tradishun.

--
Postulate a group whose intent is to destroy the United States from within
via anarchy and bankruptcy. The actions of the United States Congress are
completely consistent with the actions one would predict from such a group.

"clifto" wrote in message
news
Roger Hamlett wrote:
If (for instance), you have a 3mm shaft, and 10mm balls, the casing has
to
have an internal diameter of 26mm, and the ratio is 26/3 = 8.66:1.

I could be missing something, but at first glance I read the radius as
the diameter of the 10mm ball (10mm) plus half the diameter of the 3mm
shaft (1.5mm) and get 23mm internal diameter, ratio of 23:3 or 7.66:1.

Just in case this turns out to be a corecktion I've included speling
erors to comply with tradishun.
Yes. Sorry, I just added up the internal diameter wrong....

It is fairly simple to visualise what is happening, if you realise that
the balls are rolling round the internal diameter of the casing, driven by
the small shaft at the centre, and for the assembly of three balls to
complete one complete turn, their surfaces, must travel the internal
diameter of the outer casing. Since the surfaces of the balls are driven
by the internal shaft, you get the ratio from the ratio of these two
diameters.

Best Wishes