Unwanted movement on my Celestron 8SE while tracking.

[ggreene1]

Hello Gordon.

I have a 8SE which seems to have a similar ALT drive assembly. I noticed that the motor drive gear (the small one) was poorly supported and was likely to develop the problem you are experiencing which is caused by wear in the bush that the drive shaft runs in. I avoided this by adding a collar to the gear, which is over long, and supporting the collar with two ballraces at 120 degrees fixed to a bracket. This prevents the gear from deflecting downwards or sideways. A friend of mine refurbished a worn drive unit for a 6" by making a replacement bush for the shaft.

Peter,

I'll certainly give this idea a look. My brother is a machinist so he could probably make any bushings or parts needed. I think I'll take the drive motor assembly completely out of the scope and look more closely. If I decide to replace it, it's already out and no harm done. Good idea. Thanks

[goolosh]

Well, I was able to find a replacement motor for my 8SE. Now I just have to decide if I want the fix this one or put the money toward an EQ mount. What do you guys think ???

http://www.celestron...ct-board-1.html

If you can't fix it yourself for cheap, i would go with a new mount. But thats me. I'd like tot ry my hand at Astrophotography someday but these Celestron Nexstar mounts simply won't do. The optics are great and for the price i'm not gonna complain. I've seen lots of objects thanks to the go-to feature. Of course the mounts cost as much as another telescope LOL.

[ggreene1]

If you can't fix it yourself for cheap, i would go with a new mount. But thats me. I'd like tot ry my hand at Astrophotography someday but these Celestron Nexstar mounts simply won't do. The optics are great and for the price i'm not gonna complain. I've seen lots of objects thanks to the go-to feature. Of course the mounts cost as much as another telescope LOL.

The more reading I do, the more I'm leaning towards a new mount. I read a post where a guy said that he had only used his scope 14 times before it failed. It was under warranty, but 14 times ??? All the repair post talk about the horizontal shaft, which has 2 bearings being replaced. The shaft that has movement on my scope is the vertical shaft. The one that comes out of the gearbox. I'm afraid that if I spend 150 bucks on a new drive, it may be only a few years at best till it fails again.

I also want to do astrophotography and if I fix my mount... I still have my mount. I think I'm going to put the money used for repair of the old mount into a new one. An EQ-5 maybe.

Thanks for the input.

[Dunkster]

Sorry to hear your mount is more problematic than hoped If your brother is a machinist, you may as well ask him to whip something up anyhow - the SE mount isn't the greatest on earth, but it is _really_ portable, so as long as you can tolerate the wobble, the 8SE makes for a great grab-and-go scope. I don't want to detract from the experience of a new mount of course, but why not have your cake and eat it?

[Northern Soul man]

Hi Gordon, when these mounts first came out - along with the Meades -( I had a Meade LX90 SCT with the double fork mount on top of the tripod), thought that they were a little unusual - reason being we all know that the mount for the OTA must be rock solid - even for visual work at relatively mid to high powers, so why the manufacturers decided to just mount from one side is beyond me. The LX90 8" which I used for several years was a fantastic scope, I only sold it to part fund the 11" (if I had the funds available at the time I would have kept it). I found the mount was rock solid - yes theres always going to be trips over the tripod, the scope then settling down within a few seconds. There is alot of weight to these tube assemblies - so why they decided to go for a single arm baffles me when knowing that the rigidity of the mount is fundamental to a good nights observing.

Looking at the engineering of the gears/shafts leads me to pose the question of under - engineered parts for what is the essential part of the scope - the mount.

If your thinking of adding weight for extra accessories then a new mount is a must for you - not sure which mount though - even the mount on the cpc is very heavy and robust and standard on the cpc range - but with an EQ mount it opens the door for photography/imaging - but thats another subject in its own right.

Hope you get it sorted Gordon - as you know the folks on here are always willing to offer help and advice to steer you towards your next purchase (if your like me IT DOESN'T STOP THERE) Clear skies and regards. Paul.

[ggreene1]

Hi Gordon, when these mounts first came out - along with the Meades -( I had a Meade LX90 SCT with the double fork mount on top of the tripod), thought that they were a little unusual - reason being we all know that the mount for the OTA must be rock solid - even for visual work at relatively mid to high powers, so why the manufacturers decided to just mount from one side is beyond me. The LX90 8" which I used for several years was a fantastic scope, I only sold it to part fund the 11" (if I had the funds available at the time I would have kept it). I found the mount was rock solid - yes theres always going to be trips over the tripod, the scope then settling down within a few seconds. There is alot of weight to these tube assemblies - so why they decided to go for a single arm baffles me when knowing that the rigidity of the mount is fundamental to a good nights observing.

Looking at the engineering of the gears/shafts leads me to pose the question of under - engineered parts for what is the essential part of the scope - the mount.

If your thinking of adding weight for extra accessories then a new mount is a must for you - not sure which mount though - even the mount on the cpc is very heavy and robust and standard on the cpc range - but with an EQ mount it opens the door for photography/imaging - but thats another subject in its own right.

Hope you get it sorted Gordon - as you know the folks on here are always willing to offer help and advice to steer you towards your next purchase (if your like me IT DOESN'T STOP THERE) Clear skies and regards. Paul.

Paul,

I appreciate all your ideas regarding my mount decision. I have decided that for right now I'm going to repair my scope for about $150 USD, 95 GBP. I'm going to start saving to buy a mount that will be able to meet my needs for the rest of my life, or at least till I win the Lottery... Ha Ha. I figure if I start saving now by the time my Alt drive fails again, I should have enough to buy a really nice mount. I figure when the time comes I'll spend about 1100 GBP, like 1800 USD, on something like a NEQ6 or the like. Thanks again for being interested in my situation. Hope you see some whoppers tonight during the meteor shower...

Clear Skies,

Gordon

I have another unrelated question... Would 100 GBP be the same as 100 quid ? I was wondering if it was similar to us here in the US saying 100 dollars or 100 bucks. Just curious.

[ggreene1]

Hey All,

Just to let you all know, I decided to repair my 8SE for now and start to save for a REALLY good mount that should last me for the rest of my life and allow me to upgrade my scope in the future without having to buy yet another mount. I just don't have the money right now to buy a good mount and I don't want to settle. Thanks to everyone for your help. I appreciate it.

Gordon

[Northern Soul man]

Hi Gordon, yes 100 pound is the same as 100 quid - just slang the same as dollars/bucks. I think you've done the right thing in repairing your mount, it'll probably work alot better than the original - I've been into this hobby for a long time and over the years I've upgraded my kit to what I now have.

As with all hobbies the kit tends to be very expensive and the mounts can cost as much as a complete set up - the 8" Meade I had before my cpc was a fantastic scope as is the 8SE - I prefer the SCT's - for such a short tube they work really well and easy enough to manage on and off the tripod.

Previousy I had an 8" reflector on an home made EQ mount which I used for a few years, then had my first SCT which I preferred purely for the height at the eyepiece and not have to rotate the tube assembly when moving to different parts of the sky - but its an individual thing some prefer the reflector over the SCT's - a personal choice.

Good luck with the repair and keep us informed - take care and regards Paul.

[ggreene1]

Sorry to hear your mount is more problematic than hoped If your brother is a machinist, you may as well ask him to whip something up anyhow - the SE mount isn't the greatest on earth, but it is _really_ portable, so as long as you can tolerate the wobble, the 8SE makes for a great grab-and-go scope. I don't want to detract from the experience of a new mount of course, but why not have your cake and eat it?

Dunkster, as I'm sure you read, I'm going to fix my scope for now and save for a better mount. I think what I'll do is strengthen the old drive with bearings or the such as suggested and keep it as a backup. Thanks again...

[ggreene1]

Well my friends, it looks like Celestron has tried to address the Alt/Dec motor assembly gear problems. I just got the replacement motor drive assembly and I am impressed with the construction of it. The 2 gears look to be several times as robust than the old ones. Also it looked like they put a bearing on the shaft that comes out of the gear block. That is where all the play is on the old unit. Also there seems to be absolutely no backlash in the gearing. Maybe after replacing 10,000 or so Alt/Dec motor assemblies under warranty, they decided to build the drives like they should have been from the start. I'll post a link to pictures as I replace the unit. Have a great weekend.

[Northern Soul man]

Nice 1 Gordon - things are looking up for you, with the upgraded bits lets hope that this sorts out the mount for you, these 8" scopes are amazing - I'm a litttle bias to the Schmidt Cassegrains - a fantatic visual scope you'll have years of fun with it. Paul

[ggreene1]

Nice 1 Gordon - things are looking up for you, with the upgraded bits lets hope that this sorts out the mount for you, these 8" scopes are amazing - I'm a litttle bias to the Schmidt Cassegrains - a fantatic visual scope you'll have years of fun with it. Paul

Even with all of the problems I've had, my scope has been a lot of fun. I was able to photograph the Venus transit... http://gordongreene.com/photogallery/displayimage.php?album=78&pid=3089#top_display_media I have also had several beautiful evenings looking at Saturn, one of which was the best seeing I've had to this point. Saw 2 of her 60+ moons and was able to see the Cassini division pretty well. I sat and stared at it for an hour. Also enjoyed Jupiter (w/ 4 moons), Venus, Mars.

After this fix, I am really looking forward to seeing (and correctly tracking) the Orion Neb., Andromeda Galaxy and other wonders of the Universe... Thanks for your help throughout.

[knobby]

Great to see you're getting some use out of it !

good luck with the repairs