Nearly filled my Kimbies

Was doing some observing last night and my G11 Gemini let out a very loud squeeling alarm, and the RA stopped. I felt the motor and it was almost boiling hot, damn what could have caused this. Anyway too late to do anything last night, so got up early this morning and took the worm cover off and checked for tolerances. I think possibly the worm was a tad too meshed and was binding on the gear, adjusted as per Losmandy yahoo group recommendations and all seems ok now. I am getting too old for these sort of shocks.

[beren]

Ouch .....I left my scope once while it was it doing its alignment dance to adjust the stereo in the nearby shed and the keypad cable got caught in the rotating drivebase letting out a horrible sound . Heart attack material

[davidpretorius]

yes, a lovely quiet night under the stars listening to the hmmmmmm of a fan or drive and then WWWHHHAAAMMMOOO something does wrong

can you pass the wipes please dear!

[[1ponders] (Paul)]

Ditto Ouch....Peter, was the mesh still at factory default "pressure"? I hope everythings still OK

While I've only played with 3 G11 and a GM8 I was surprised at the difference is Dec backlash in each of them. My G11 has very little backlash, Strikers has much more, and the Mapleton Observatory has a lot of Slop. None of these have been adjusted (factory default meshing) and the oldest is the observatory one and it's only about 18 months old and doesn't get a lot of work. I've not checked the RAs by taking the covers off, though there does seem to be a fair bit of slop in the observatory one while mine seems to be ok with no real noticable delay when switching direction in RA. Mind you that doesn't mean it isn't meshed too tight, just that its not too loose.

My GM8 has next to no backlash in Dec and when I checked it out (as per the yahoo group) found that both the RA and Dec were so tight there was no way I could turn them by hand. I don't know if they had been adjusted before I bought it (second hand). I've loosened them off a bit but haven't had a chance to try it out since. I didn't want to loosen them too much as I feared that if they were so tightly meshed before there might have been excessive wear and loosening them to the yahoo specs would have led to too much backlash/slope?

You'd think think that for such a highly recommended mount that there would be a standard mesh pressure or backlash allowance set in the factory.

BTW something else I noticed was that as the mount cools down during the night that moving by hand in RA and Dec becomes easier and less "sticky" without adjusting the clutches. Either there are pretty tight tolerances in the shaft/bearings that becomes freer as the night cools and the metal contracts or the grease becomes less viscous as it cools (unlikely).

Also does Losmandy use the same glue/grease that synta uses. My RA and Dec (particularly the Dec) suffers pretty badly from that perennial Gem problem of stickiness in initial movement by hand and maddening when trying to do small movements by hand.

It was at factory settings, and the dec was spot on. However the RA had lateral slop in the worm bearing blocks. I adjusted this out last week, but didn't check the "meshing for free movement". However I think that where I went wrong last night was I started the scope up not in the CWD position and I believe the ra reached its limit without giving an audible warning and continued to try and run, thus heating things up. The warning I got I think was some sort of temp warning. Today I pulled the RA motor off the mount and adjusted the block positions with a feeler gauge, there is no slop within the bearing blocks and absolute minimal backlash in the gears. I can rotate the worm freely without any binding, and I think this is the way it is supposed to be. I have attached a pdf file from the yahoo losmandy group showing the method of adjustment.
As far as the grease goes, I have heard unofficially they use Slick50, also heard they use a lithium based grease, so take your pick on that one.
Anyway tonight no probs at all the RA motor was cool as a cucumber, touch wood.



OOPS the file is too big to upload. If anyone wants it PM me.