Re: Mach1 play in RA Axis - did not adjust out with Gear Mesh adjustment

Roland Christen

The Mach1 is an extremely simple mount. The RA axis has two bearings, one at the upper end of the RA body and one near the middle of the body. There is a sliding window on top of the RA body that can be slid up and out of the way (this is the window where people run their cables thru the mount).

Sliding this window out of the way allows you to actually look inside the RA body, which is hollow, and you will see the shaft bearing retaining nut that preloads the bearings. It's a black anodized ring with two holes on the ends that allow a spanner wrench for tightening. Further up you can see the shaft which is clear anodized (silver). The bearing itself is underneath the black ring.

If it's loose, then the axis shaft can move a bit inside the bearing. You can look right in that opening and see the end of the RA shaft bearing retaining ring and check to see if it moves as you push on the counterweight shaft. You can even put your finger on the retaining nut and feel if there is any movement if you can't see it by eye.

There is nothing whatsoever left that can allow the RA axis to move when you push back and forth on the counterweight shaft.

Roland Christen
Astro-Physics Inc.

-----Original Message-----
From: John Davis <johncdavis200@...>
Sent: Thu, Oct 1, 2020 4:59 pm
Subject: Re: [ap-gto] Mach1 play in RA Axis - did not adjust out with Gear Mesh adjustment

Hi Roland,
  I went back and meticulously re-read your first post, and attempted to the best of my abilities to re-do everything that you suggested- just as you suggested, including the steps to familiarize myself with the behavior of the meshing mechanism.  Everything behaved just as you described.

  I re-performed the meshing procedure following your instructions and those in the documentation for the mount.  That procedure still did not ellimnate the play in the RA axis, as it DID when I performed the same procedure on the Dec axis.  Because that worked, I conclude that I followed the procedure correctly.

  I then added your last step to move the lever to the 90 degree position from fully locked, and gently with one finger pushed back and forth on the end of the counterweight shaft - and it still moved as it does when the lever is pointing to the fully engaged and locked position.

  After all this I re-checked the worm nut - with the cap removed, I cannot feel any movement of the worm shaft when moving the counterweight shaft with my finger.


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