Hello Tony,

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The original mount came with stainless worms.

I have purchased one OPW and two High Precision worms for both RA/DEC. I was considering the OPW for the RA axis but will think about using it in DEC. My OPW came with a hole that may be used for Sprint loaded, but no spring was included, just a hole. Thats very strange. Please check this post: /g/Losmandy_users/message/73027

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I have checked your onstep progression. What controller have you used? What was the tracking microstep configuration? I have upgraded the stepper controller to TMC 5130.

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Thanks for the reduction suggestion. I will think about it.

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Thanks

Andre

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De: [email protected] [mailto:[email protected]] Em nome de GuitsBoy
Enviada em: quinta-feira, 29 de julho de 2021 10:18
Para: [email protected]
Assunto: Re: [Losmandy_users_io] What result I can get with the current OPW in my old G11?

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Hi Andre -?

Did your original mount come with the HP brass worms?? Or were they stainless?? ?Assuming they were HP brass already, the new OPW might not offer much less PE than your original ones, however it should be a whole lot easier to set the backlash.? And if you ever decided to go DIY spring loaded worms, it should be a relatively easy mod for you.

Also, I would think you want the High Precision worm to go on the RA side to reduce periodic-error.? ?Personally, I would put the OPW on the DEC side with the expectation that I would eventually do a spring loaded mod to reduce backlash, or at the very least, make routine backlash adjustment easier.

I also have a ten+ year old G11 that's been converted to onstep.? ?To give you an idea of how my RMS guide error progressed:

~ .85 - 1.0 arc-sec RMS:? ?Direct drive 400 step motors and stock two piece worm blocks
~ .6 - .75 arc-sec RMS:? ?Belt Drive with 16:60 reduction and stock 2 piece worm blocks
~ .5 - .65 arc-sec RMS:? ?Belt Drive with 16:60 reduction, and DIY spring loaded worms, new HP worm (old was brass, but high PE) and bellows style couplings

The above assumes nights of good seeing and little wind.? ?I am still using a 60mm guidescope, and? I've had 30 lbs of 8" newt and equipment guiding under .5 arc-sec RMS under perfect conditions.

I should also note that certain stepper drivers perform better than others.? The TMC2130 seems to contribute the least error.? ?Also, mechanical reduction is more accurate than microstepping for two reasons:? Coarser microsteps are more accurate and have higher holding torque, and mechanical reduction also reduces load on the motors, resulting in less angular error.? If you can move towards mechanical reduction (planetary gearbox or belt drive) that should give you additional benefit IMO.? But you have to make sure that the reduction benefits outweigh the added complexity, friction, and NVH (noise, vibration, harmonics)

Good luck, -Tony