Over the past few weeks while following the discussions here in the user group and tearing down and servicing my recently acquired G-11?
I'm learning that there are some fundamental design issues that are limiting performance, affecting both accuracy, and repeatability and usability.
I think it is important to make the distinction between operational issues and complexities that can be solved with improved processes and technique?
and those that run up against design limitations that can't be solved by simple improved parts.
This thread is focused on identifying the mor fundamental issues, mitigation and suggestions or ideas to solve them that require design changes.
I give all credit to the community and experienced users that have identified these issues, worked on solutions and have spent countless hours and money
documenting problems and testing solutions.and documenting improvements. I have my own thoughts too which add to the discussion but my purpose here
is to organize the information. My hope is that this will facilitate participation by members connected with Losmandy with the goal of engaging Scott in the discussion
and turning these ideas into actual reality.?
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- Use of axial needle roller bearings for the RA and DEC axis shafts
- ?They are not pre loaded.
- Bearing load is uneven causing uneven wear on the axis.
- required shaft clearance causes mis-alignment of the axis (axis 'sag') and non axial rotation
- ?do not prevent wobble
- Thrust bearings are not implemented properly
- Bearings are not pre-loaded.
- Bearings are loaded based on clutch operation not on proper setting for shaft rotation dynamics
- Bearing pressure not consistent. RA axis drag and dynamics not predictable or repeatable.
- Thrust bearings do not prevent non axial movement of the axis
- Bearing are exposed to the elements.
- Clutch functionality
- Lack of mechanical indexing makes it impossible to recover from
- Releasing the clutch to perform required operations such as balancing disrupts the mechanical adjustment and calibration of the drive.?
- Clutch slip can occur and it is impossible to identify or quantify the loss of mechanical alignment calibration and adjustment
- It is impossible to accurately restore positional orientation after releasing the clutch.
- Operation is neither repeatable or reproducible
- Clutch pressure setting determines axis shaft thrust bearing load. Undesired cross effects
- Unloaded bearings can become misaligned.
- Thrust bearing load impacts drive motion dynamics and alignment.?
- No indicator or way to consistently set the clutch pressure
- Unwanted negative impact on drive performance.
- Clutch action is unpredictable
- No indexing of mechanical components
- Impossible to maintain repeatability or reproduce performance.
- Mechanical alignment and adjustments are lost during the course of normal operations.
- impossible to reproduce mechanical alignment and adjustments.
- Inconsistent results even when following the same procedures.
- Software based motion correction
- Software based motion correction gets out of sync with the mechanical position of the drive.
- Due to lack of indexing it is impossible to resync the software with the mechanical system.?
- Out of sync condition is only discovered by degradation of collected data and changes in guiding performance.
- Must eliminate other causes of poor data and guiding.
- Time consuming and data loss.
- Impossible to recover error correction data and apply it or re-apply it accurately.??
- There is no way to determine if the software motion control corrections are correct without fully testing and calibrating the drive.
- Fully testing the existing corrections takes as much or more time or more than starting over and collecting new data.?
- Stored PEC makes the guiding worse if it's out of sync by interfering with auto-guiding applications
- Gear reduction ratios causes un-correctable PE errors
- Gear ratios are not even multiples so the periodic error is also not an even multiple. It is 'out of phase' so shifts over time
- Alternative gear box from McLennen has same 25:1 ratio but the intermediate ratios are even multiples and can be corrected with PEC.
- Worm adjustment and mounting
This is a list of issues. I will try to bring forward ideas that are posted in other threads about solutions and link them in this thread.
Regards,
Michael
