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EXOS2/PMC8 RA Gear rubbing on plastic post -> solved


r_hoskin@...
 

Hi! 

Just a short post about a problem I found and its solution, in case someone else has this as well. FYI, etc., etc...

Cyril's post made me curious about what was under my drive covers.  I don't appear to have his issue, but I found something else...   The large toothed pulley of my RA drive was positioned up hard against, and literally rubbing on, the nearby plastic post that receives one of the cover screws.  (The cover screws are the four small phillips at the outer corners of the drive case)

Shortening a long story (lots of PM's and emails...), the fix (thanks, Jerry!) turned out to be quite simple. 

With the cover off, power up and nudge the drive until setscrew holes rotate into view on the large pulley.  Mine has two.  A dot of magic marker helped to tell them apart.

I could not see the setscrews in the holes.  They were tiny, and down deep, but my smallest metric hex key was able to engage and loosen them.  With the screws loosened, the pulley was easy to reposition inboard on its shaft and away from that post.

Close cover, and done.

- Bob



David Pickett
 

I am moved to wonder what procedures are in place at the factory for correct assembly. :)

That's at least two people who have posted here about having to do important adjustments on new mounts -- in Bob's case, quite a tricky one.

David

At 17:04 20-01-18, r_hoskin@... [ESPMC-Eight] wrote:


Hi!

Just a short post about a problem I found and its solution, in case someone else has this as well. FYI, etc., etc...

Cyril's post made me curious about what was under my drive covers. I don't appear to have his issue, but I found something else... The large toothed pulley of my RA drive was positioned up hard against, and literally rubbing on, the nearby plastic post that receives one of the cover screws. (The cover screws are the four small phillips at the outer corners of the drive case)

Shortening a long story (lots of PM's and emails...), the fix (thanks, Jerry!) turned out to be quite simple.

With the cover off, power up and nudge the drive until setscrew holes rotate into view on the large pulley. Mine has two. A dot of magic marker helped to tell them apart.

I could not see the setscrews in the holes. They were tiny, and down deep, but my smallest metric hex key was able to engage and loosen them. With the screws loosened, the pulley was easy to reposition inboard on its shaft and away from that post.

Close cover, and done.

- Bob


r_hoskin@...
 

David,

Agreed. Fortunately, this was just an assembly adjustment that was out.  I'm actually embarrassed that I didn't figure that out on my own once I saw the problem, and it wasn't hard to take care of, once the solution was understood. Cyril's problem sounded worse to me, and I'm still trying to figure out why he had a problem that (knock on wood), I don't see on my mount.

But... if I'd left the drive cover on and hadn't seen that pulley out of position, I'd have just had a mount that didn't track well and didn't respond to the usual prescriptions.  Hence the post - one more thing to check, if all else fails. 

I still need to work on my PA, but I bet my luck improves now.  :-) 

- Bob


David Pickett
 

Bob,

As I understand it, the problem was due to
something not having been adjusted correctly, but
tightened up all the same; and not simply due to a loose screw, which can happen. Cyril's problem was of a similar nature.

I hope the information has been fed back to ES,
so that they can attend to other potential problems at source.

Good luck with the PA and guiding. I hope you are
not affected by the almost constant clopuid cover
that we have had in Europe for weeks!

David

At 19:41 20-01-18, r_hoskin@... [ESPMC-Eight] wrote:


David,

Agreed. Fortunately, this was just an assembly
adjustment that was out. I'm actually
embarrassed that I didn't figure that out on my
own once I saw the problem, and it wasn't hard
to take care of, once the solution was
understood. Cyril's problem sounded worse to me,
and I'm still trying to figure out why he had a
problem that (knock on wood), I don't see on my mount.

But... if I'd left the drive cover on and hadn't
seen that pulley out of position, I'd have just
had a mount that didn't track well and didn't
respond to the usual prescriptions. Hence the
post - one more thing to check, if all else fails.

I still need to work on my PA, but I bet my luck improves now. :-)

- Bob


r_hoskin@...
 

Yes, the pulley just needed to be relocated inboard on its shaft.  It was not loose, just mis-positioned.

When I first looked at it, no setscrew holes were visible (so I headed off in the wrong direction, looking for other solutions).  Turning the pulley by hand wasn't going to work, I didn't want to mess with the belt tension, and of course, the PMC8 was disconnected for disassembly.  Just as only one side of the moon shows, so it was with that pulley... 

Jerry sent me back to look for setscrews, and after reconnecting, powering up, and inching the drive, I found that the tiny little devils were hiding on its far side.

Yes, ES has this now, from multiple directions.  My dealer (Ontario Telescope) jumped in to help. too.  :-)

I'll do an update on PA when I have more.  New gear has been added, but the weather here has been awful, sky-wise...


r_hoskin@...
 

I had mentioned that I had not yet checked out the Dec pulley for this problem.  It's ok.  That pulley is more or less centered on its belt and is clear of its plastic post and the belt tension looked ok.

So many learning experiences :-))   Phillips-head screws and I aren't friends at the best of times, and a couple of the Dec drive's cover screws are in deeper than I could reach with my #1x50mm driver.  The discovery part had to do with finding that a hardware store #1 Phillips (from my existing toolbox), and a #1xWhatever-mm...are not necessarily the same size...  

Anyway, a #1x100mm Phillips was secured today.  That fit the screws I couldn't reach before.  The cover then came off easily, and the pulley was found to be in the right position on the shaft. 

Clear skies are predicted for tonight.  It's been a month of either cloud or can't-go-out already.  Hoping to take another run at that PA tonight.  We'll see...

- Bob   


David Pickett
 

At 21:42 25-01-18, r_hoskin@... [ESPMC-Eight] wrote:

So many learning experiences :-)) Phillips-head screws and I aren't friends at the best of times, and a couple of the Dec drive's cover screws are in deeper than I could reach with my #1x50mm driver. The discovery part had to do with finding that a hardware store #1 Phillips (from my existing toolbox), and a #1xWhatever-mm...are not necessarily the same size...
I am not a fan of Phillips screws, but I have acquired many Phillips screwdrivers over the years. I do not know what # size they are; but it is my experience that the one that works (i.e. without slipping or destroying the head) is always larger than one might expect from looking at the screw.

Clear skies are predicted for tonight. It's been a month of either cloud or can't-go-out already. Hoping to take another run at that PA tonight. We'll see...
I hope all went well!

David