Hello:
I have a Losmandy G-11 with a 50lbs 12.5" cassegrain on it. This scope is pretty close to the limit of what the mount can handle; it is both long and heavy. So, it's not too surprising that the scope is less than rock steady on the mount. I would still like the scope to be as steady as possible. To this end, I intened to install a strut from the end of the counterweight shaft to the end of the tube.
However, the main source of flexture is in the RA clutch pad area. I have adjusted the gear mesh to minimize backlash. When I wiggle the scope back and forth (not enough to make the clutch slip, just enough to simulate wind shake) in the RA direction, the motion seems to be at the interface at the clutch pad. When I wiggle the scope while my thumb is pressed over the RA setting circle and vernier, I can feel a little differential motion. The motion has a resonant frequency of about 2Hz. I have found that reducing the friction on the clutch (with he knob at the back of the RA shaft) reduces this instability, but then the scope is free to move on its own. My question is: what can I do to reduce or eliminate this instability? Will replacing the clutch pads with the ultra-high molecular weight stuff help? Is there some home brew fix that I could try? I suppose I could get a heavier duty mount, but I'd prefer to try the less-than-$10000 options first!
Cheers
Mike Connelley
I have a Losmandy G-11 with a 50lbs 12.5" cassegrain on it. This scope is pretty close to the limit of what the mount can handle; it is both long and heavy. So, it's not too surprising that the scope is less than rock steady on the mount. I would still like the scope to be as steady as possible. To this end, I intened to install a strut from the end of the counterweight shaft to the end of the tube.
However, the main source of flexture is in the RA clutch pad area. I have adjusted the gear mesh to minimize backlash. When I wiggle the scope back and forth (not enough to make the clutch slip, just enough to simulate wind shake) in the RA direction, the motion seems to be at the interface at the clutch pad. When I wiggle the scope while my thumb is pressed over the RA setting circle and vernier, I can feel a little differential motion. The motion has a resonant frequency of about 2Hz. I have found that reducing the friction on the clutch (with he knob at the back of the RA shaft) reduces this instability, but then the scope is free to move on its own. My question is: what can I do to reduce or eliminate this instability? Will replacing the clutch pads with the ultra-high molecular weight stuff help? Is there some home brew fix that I could try? I suppose I could get a heavier duty mount, but I'd prefer to try the less-than-$10000 options first!
Cheers
Mike Connelley
