Quote:
Originally Posted by pmrid
G'day David.
Long time between shouts!
I'm sneaking up on this project very slowly and carefully. I thought I was being adventurous when I bought a Raspberry Pi. But Arduino is something else again. I've ordered the core elements most people seem to recommend - an Arduino Leonardo, a L298P, LCD1602 and a Temp Sensor DS18B20. For the massive investment of US$32.95. Buying locally would have been more than double. But while I wait for those bits to arrive, I am also expecting the imminent arrival of a couple of motors and control boards.
What eludes me for the moment is the mechanical issue of how to get the motor to drive my focuser - I ought to have bought a geared motor I suppose but that's definitely being wise after the event. Do you use belts or gears to drive your focuser? And how did you determine the appropriate gearing ratios?
Peter
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Hi Peter,
Apologies for a slow reply,
Definitely high finance on these things
I am using the motor that came with the micro touch controller. After much trial and error I worked out the wiring connections. This setup uses a gear mechanism to connect to the focusing shaft. The shaft it connects to is the small knob of a 10:1 reduction system anyway, so there is a lot of reduction built into the system.
From what I read in his documentation, the NEMA17 motor is direct drive. You'll need some sort of reduction using belts and pulleys (probably be easier for adjustment than gears) to give enough accuracy. There is another stepper motor that has a reduction gearbox built in - you might be able to connect that directly to a focusing shaft. The Robofocus motors have a reduction gearbox and connect directly to the focuser shaft.
He has lots of calculations about critical focus zones in his documentation. I skipped over that as I was using an exisiting motor and gear mechanism - I just needed the controller to drive the actual motor.
I do plan to make up another controller and motor system for another telescope and a camera lens, so I might be able to offer some more advice after that - although that will be in the new year. I'm planning on 3d printing some brackets to hold the motor, belts and pulleys.
Hope you don't get too drenched in the upcoming weather event.
DT