Replacing motors on an eq3-2

[bluemaxroe]

Hi everyone.  I have an eq3-2 and the dec motor is really bad for slack.  I was wondering if it is worth swapping out these motors for much better ones.  If I do this do i need to calculate the gearing etc? Or can Phd do this with calibration?  I would only be using the mount for super widefield imaging with a camera and max 200mm lens.

Any advice would be appreciated.

Is it better to just find a new(er) better replacement eq3-2 dec motor?

[Dr_Ju_ju]

What is slack on the motor ?  there is usually slack\backlash  in the meshing of the gears being driven by the motor, so the better place to start would be to perform an adjustment routine, to reduce any slack\backlash in the system....

This is preferable before changing the motors....  although I've not tried it, it may also be possible to upgrade to a belt driven system, which will also 'clean-up' the drive system.

 

[bluemaxroe]

I am not sure any adjustment routine would a just for this much slack...when changing direction the dec motor takes 2-3 seconds to show motion.

[Dr_Ju_ju]

Yep, that sounds like the 'expected' backlash... You need to adjust the motors to worm-wheels slack, then the worm-wheels to axis engagements.....   There are some YouTube videos showing you how to do this....

[JamesF]

I always found the backlash to be very bad on the DEC axis with my EQ3-2.  I think part of it is unavoidable.  Inside the plastic housing of the motor unit there's not only a motor, but a reduction gearbox too.  It has quite a number of gears in and has a fair bit of backlash as a result.

I started to move to stepper motors and AstroEQ (which means controlling it from a computer), but then bought a HEQ5 and never really finished the job, though I was looking at it again the other day.

James

[JamesF]

Come to think of it, I have a nagging feeling that at one point I took the external gears off the motor and DEC worm and either reconnected them using a belt drive or just drove the DEC axis directly from the motor output.  That does require making up a new bracket though.

James

[JamesF]

So I did.  I made up a new bracket from a skanky bit of aluminium angle I had lying about, and remounted the motor on it to drive the DEC worm directly:

It helped, but not enough for what I wanted.  To be fair I was trying to image globs with a 127 Mak.  Even the HEQ5 Pro isn't too hot at that without guiding.

James

[bluemaxroe]

Hi James, 

That's more what I was thinking.