Solar cooker or solar panel tracker. something to move a 300 gram weight up or down at 20 mm per hr.

I have asked on facebook, etc. and had no luck.  It's weird,  I ask a specific question and people will answer a different one.   But half decent answers were from a couple of people.  Someone suggested a stepper motor and another person said a recycling timer to control a motor.  So, that's a start.    300 grams is about 10 ounces and 20 mm is about 3/4 of an inch. I want to set it up and then for it  to move the weight for up to 16 hours at that speed.   I need to start the project next week.  The only part I can't do is accurately move the weight up and down.  It's to control several solar panels or solar cookers as they track the sun across the sky.  I will be using air (a "pneumatic grid) " to both control and to move the solar devices.  They will be in different places in my back yard and the controller with the precise motor movement  will be in a shed.  Can anyone help me here?   Ideally, the cheapest solution.   Thanks Brian

Thinking out loud...

- you probably need something rotating because motors are much less expensive than linear drives.
- converting the rotation into linear motion at a constant ratio without slipping makes a chain ideal. (And bike chains and sprockets are plentiful)
- a 10teeth sprocket has a radius of 20mm.
- so you need 1/(2 Pi) rotations per hour.
- And then as many stages of reduction as required so your stepper motor has enough torque.

EDIT:
If my math is correct, 0.3kg * 10N/kg * 0.02m = 0.06Nm. With each reduction that goes down + some friction.

Maybe a 0.6 RPM gear motor
https://www.amazon.com/BEMONOC-DC-0-6RPM-Torque-Turbine/dp/B01D147LDK/
Driving a 32 thread/inch leadscrew, 12 volt motor run at 8.5 volts.


I’m not sure I would do that though, when there may be simpler ways.  https://m.youtube.com/watch?v=Oj1E7o7J3qc

Too bad a 24hr european/military-time clock probably doesn’t have enough torque…  turns at the right speed!

Mike Philips wrote:Maybe a 0.6 RPM gear motor
https://www.amazon.com/BEMONOC-DC-0-6RPM-Torque-Turbine/dp/B01D147LDK/
Driving a 32 thread/inch leadscrew, 12 volt motor run at 8.5 volts.


I’m not sure I would do that though, when there may be simpler ways.  https://m.youtube.com/watch?v=Oj1E7o7J3qc

 I want to accurately point multiple  solar cookers at the sun. The simple tracker that you show can't do that.  I'll check out the amazon link.   I was told stepper motors because they step and the speed of the steps can be changed.  Thanks