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#1 UniversalMaster

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Posted 13 October 2013 - 07:40 AM

Hi!

I plan on using a geared DC motor with my Shoestring to make a motorized focuser. However, what is good gear ratio on the DC motor? I plan on attaching it in about 1:1 to the 1:10 focus knob...

Clear Skies :jump:

#2 Geo.

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Posted 13 October 2013 - 09:44 AM

Well, gearheads have all kinds of ratios. Some scope drives are 1:300. So your gearhead may have a lot more effect on overall ratio than your final drive.

You also have a lot of latitude depending on your motor's efficiency. If it will run on low voltage you can play with that for speed regulation. The JMI/Celestron Dec drives had a built in pot to alter the speed.

#3 UniversalMaster

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Posted 13 October 2013 - 11:56 AM

Yeah, thanks for your answer. This is for a moonlite 2" focuser. Anyone know what ratio their own DC focus motor is using?

#4 Raginar

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Posted 14 October 2013 - 12:23 PM

Nope. I have one lying around. You could just direct mount it :)

#5 Mert

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Posted 14 October 2013 - 05:15 PM

I use a 2" Moonlight, but opted for a stepper motor.
A 1:4 reduction from stepper to focus knob is used and
also microstepping is used so rather fine focus control.
Should have some image around on CN but can't find it
anymore.

#6 obin robinson

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Posted 14 October 2013 - 06:00 PM

Hi!

I plan on using a geared DC motor with my Shoestring to make a motorized focuser. However, what is good gear ratio on the DC motor? I plan on attaching it in about 1:1 to the 1:10 focus knob...

Clear Skies :jump:


I have the FCUSB as well. I just ordered this motor:


http://www.amazon.co...0_i00?ie=UTF...

I plan on using the FCUSB in a dedicated camera platform but that nice slow motor should work quite well. I am going to take a trip to the local hobby shop and see if I can find some gears and belts which will work for me. I figure with all the RC cars out there something should work.

obin :)

#7 UniversalMaster

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Posted 16 October 2013 - 11:43 PM

thank you. now i have something to look for! i might end up just getting the orion dc motor, but it has loads of backlash. these might be better?






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