CGEM Torsion Balance

This might solve the problem of needing to rebalance after a meridian flip. In particular, when done automatically as part of a long automated imaging sequence. It maintains RA gear load on both sides of meridian. With this, the mount should still be balanced so the OTA is slightly heavy on the east.  The torsion spring has little torque in this position....as the OTA tracks toward the west, the torque increases and will ultimately overcome that bias and maintain gear load even when the OTA is on the far west side of the mount.  

Revision 2: I bought a 7x10 mini lathe and fabricated the parts from aluminum stock....aka hobby creep.  (note...should have listened to reviews and got the 7x12 (or bigger) but I was too impatient as the 7x10 was in stock at local Harbor Freight store). 

Spring holder threads into polar scope hole, machined from 1 1/2 inch hex stock

Outer collar will thread on to the orange ring (above)..still needs holes drilled to hold the spring.  machined from 4 inch x 1/2 wall aluminum tube.  This technically exceeds the limit for my lathe....but is doable.  

  The torsion spring is fixed to the collar by a 1/4-20 bolt with a center bore

Attached to Orange collar that covers rear RA bearing.  Set screw(2 positions 60 degrees apart) allows for torsion adjustment

The Collar:

Plans can be downloaded for a $5 donation:

After your donation is received, please allow up to 48 hours for an email to the download link. 

Revision 1:  bigger 270 degree spring. The video shows the mount is east heavy on both sides of the meridian without changing weight position.

This Works!  Below are screen captures of guiding just prior to and after a meridian flip.  This shows near perfect guiding with the OTA on the far west of the mount (spring at max torsion) then after meridain flip w/ OTA on far east side of mount.  No counterweight changes were made at all.  PHD calibration data was flipped.

                        Before Flip (OTA on far West)

                        After Flip (OTA on far East)

(Below) Very preliminary build.