On 1/8/20 3:04 PM, Steve Bookout wrote:
Hi Mac,
I've rebuilt several P/P gear boxes and have had issues in the past with
the grease being too thick in the high speed planetary gear area. When
the wx would get really cold (for VA) in the teens, it would want to
turn so slowly that it would 'fault' the Green Heron controller. This
was when I had it set up for 'ramping' the speed up/down. I would just
have to change the 'ramp' setting to get it working again.
So, the last time I did any, I did a bunch of research and found Amsoil
Arctic grease.
https://www.amsoil.com/shop/by-product/grease/arctic-synthetic-grease/
The performance ratings are fine and comparable to other greases, but
it's good for really low temps. The viscosity reminds me of hair gel;
not really thick at all. And, it synthetic! Temp range of -75 to 315
degrees F.
The other approach is a small thermostatic strip heater. That's what we
do for dish pedestals that are in areas that get cold, but not arctic.
(say down to 0F). Depending on how your controller is set up, you might
just be able to parallel the heater with the DC power to the motor, so
you wouldn't need to run additional power. You'd command a move, and the
motor would turn slowly, but the heater would also turn on, softening
the grease. After a couple moves it might well have solved the problem.
The Omega catalog is one place to start, but they're also available from
the usual industrial suppliers like Grainger & McMaster (and, I'm sure
Amazon from some previously unknown manufacturer in China) - they're not
an exotic device, and they're available in a variety of resistances,
power ratings, etc. Finding one to work on 12V or 28V would be no problem.
You could probably also epoxy a resistor the side of the rotator, but I
think the self adhesive strip heater (or a heater under a band clamp)
would be more elegant.
{I hesitate to suggest it, but since someone was in my office talking
about laser propulsion the other day: All you need is a high power (say
10W) laser on the ground pointed at your rotator on the tower, which you
have painted or covered with a suitable absorber. You can get a
frighteningly high power laser for a remarkably low price. You could
also use this to melt the ice off your yagi, I suppose. And to solve any
problems that the plastic owl didn't fix.}
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