So, surprisingly, those three bolts are all that holds the above item
to the Optical Tube Assembly. The above is a view of the
shaft. The inner screw hole is what the large Dec knob that
tightens the clutch goes into. The two outer screw holes are the
ones that hold the Main gear tight against the shaft. The above
item appears to be a single piece of cast aluminum. I could not
see any way for the shaft to rotate against the rest of the above
item. Yet it seemed like it MUST be rotating to allow the
slippage I was seeing. I was not positive that the above item was
really one piece though. Maybe somehow part of it could rotate
against the rest of it? The problem was how to test it.
I then realized that to be sure, I had to test it with the main gear
attached and see what was rotating against what.
So I then assembled the pieces that matter:
So in the above image, you see a side view of the shaft and the black
plate it is part of. The main gear is bolted to the shaft using
the two screws that I took out previously. Then on top of that is
the other plate mentioned before which I think constitutes the
clutch. Then the Dec clutch knob is above that screwed into the
center hole of the shaft. I tightened it down then carefully
positioned the left end of the plate in the above image into a vice but
DID NOT TIGHTEN THE VICE. That is cast aluminum! I didn't
want to damage it! But I used the vice to stabilize it so I
could twist the main gear and see if anything rotated. Surprise!
Surprise! Something DID rotate! It shouldn't but it
did! I looked carefully at the clutch/main gear and they were not
slipping against each other! Impossible!
This next image shows the screws holding the main gear to the
shaft. Look at the two screws (there is an allen wrench in one of
them.) The heads are cone shaped to exactly fit into the cone
shaped counter-sinks. If they are tight, there is NO WAY the main
gear can rotate against the shaft.
Well they were tight but the main gear WAS rotating about the
shaft! How could that be? Then it dawned on me. The
*$#!&#$ screws were too long! They were tight. Tight
against the bottom of the screw holes but not tight against the Main
gear! If they are not tight against the main gear,
then the gear can rotate a tiny bit about the shaft!
This following image shows the screws tight against the bottom of the
screw holes without the gear attached. They are in all the way.
They are just flat-out too long! When the Main gear is in
place, they bottom out and do not allow the Main gear to be completely
tight against the shaft.
Solution. File the two screws down a bit, i.e., remove
about two threads.
I did that. Reassembled everything. NO MORE SLIPPAGE.
The Meade clutch works just fine. Meade either did not drill the
screw holes deep enough or somebody provided screws that were longer
Tough problem. Hard to analyze. Counter-intuitive.
So, here's all you have to do if you
have this problem. You don't have to
disassemble the fork arms or remove the above plate like I did.
Just remove the Dec knob, the
Dec cover, remove the clutch plate, remove the two screws, file them
down (reduce their length), screw them back in, replace the clutch
plate, replace the Dec cover and the Knob and you are back in business.
In my case, since I removed and reassembled all that stuff, my scope is
now not properly aligned with respect to the Dec Axis. I aligned
the Dec axis on the other scope years ago using Polaris so I will have
to do that tonight for this scope. Having the Dec axis properly
aligned GREATLY improves the pointing accuracy! 21 Sep 2008.