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I am worried my Orion XX12G is a lemon. Need input

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#1 twoballscrewball

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Posted 22 July 2014 - 12:22 PM

Hi all,

Bear with me and grab a coffee..., but please read and help me out if you have a minute or five.

Bought a new xx12g direct from Orion. Arrived weekend of July 4th.

When it arrived, it had two issues. First issue was that the screen in the hand controller was dislodged internally so that it was crooked, and some of the bottom line of text was cut off. Second issue was that the focuser grinded badly mid focus, to the point it would get stuck sometimes. I contacted Orion on July 9th and they were great about it, offered to send out replacements for both items. Today is July 22 and they're still not here, so a couple days ago I took it upon myself to open up the hand controller, re hot-glue the screen in place (it was hot-glued from the factory but broke loose) and I also disassembeld and tuned the focuser so that is also good now. Not pleased with having to do this on my new $2100 scope, but whatever. (And I realize it's not a $15K obsession or something like that, but $2100 is still a substantial chunk of my change lol). I neglected to take photos of the hand controller before I fixed it.

I also noticed that the scope does not track smoothly. I know this is not a $1500 GEM mount with a clock drive, and it uses a pair of steppers which are inherently 'notchy', but it seems more like the scope sticks then moves a bit, especially noticeable at anything at or below 10mm (152x). Posted here about it, folks said it didn't sound normal, I said I would get it on video which I did and will link to below.

Another thing I noticed was that with the clutches loose (fully), the azimuth motion is super loose as expected, however the alt motion is still sticking like the clutches are dragging or something else is going on. The scope does not freely pivot on the alt axis, as is actually specifically mentioned in the manual that it should.

Last night I pulled the plastic cover off of the alt sensor/motor unit. I found aluminum metal shavings on and in the drive gear, and also in the plastic gear teeth that turn the position sensor. Photos below. I do not think this is normal.

Additionally, I have been having a hard time getting everything completely concentric in collimation. I like to think I know what I am doing but who knows... Anyway, it always seems like the secondary image is offset from the center of the spider crosshair. Looked more carefully at this today and it seems like maybe the secondary is not properly attached to it's holder at it's center, but rather offset a bit. Photos below, again.

Almost done..... I also noticed this morning that two of the spider veins are a bit bent, twisted where they attach to the secondary holder. Without forcing them back into shape, which I have not done yet, it is impossible to get the spider veins to be completely parallel to the scope axis, due to the twist some part is always offset and 'wider' than it should be in the optical path.

And finally, this is more of a question as to normal behavior than a gripe, the scope has a good amount of free play in the altitude axis even with the clutch completely tight. In other words, when the clutch is locked, I can still move the scope up and down a couple inches at the secondary end before it encounters any resistance.

I need to know what I should do here. I am going to contact Orion, but first I want to quickly pick your brains, especially other Orion GoTo Dob owners, as to how this all relates to what you have experienced with your scopes. What is normal and what is not?

Thank you, pics to follow in posts below. I will likely ask Orion to reference this post when I call or email them so please keep it as constructive and fact oriented as possible.

Thanks!

#2 twoballscrewball

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Posted 22 July 2014 - 12:32 PM

Metal in the alt mechanism:

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#3 twoballscrewball

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Posted 22 July 2014 - 12:34 PM

Collimation issue, seems like secondary maybe not centered on holder?

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#4 twoballscrewball

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Posted 22 July 2014 - 12:59 PM

Tracking performance at 152X (10mm). Forgive the horrendous seeing, as I was 'seeing' directly through the plume of heat and smoke from my neighbors fire pit to hit Saturn :)

note this camera is permanently affixed to an eyepiece, so all motion is from the tracking action, the scope was otherwise untouched and there was no wind.

https://www.youtube....eature=youtu.be

#5 KerryR

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Posted 22 July 2014 - 01:20 PM

I think everything is fine with the secondary-- I believe it has offest built in, so it won't be centered from the front.
The spider can be adjusted to straighten, but it's more important that the secondary appear centered under the focuser when looking down the tube. If doing this adjustment bends the spider too much, you can instead center the spider hub in the tube and shim the focuser instead. Then collimate as normal. All this is not a big deal.

I've never used the scope in question, but the other mechanical issues sound real. Not so much the shavings; I doubt they're doing anything damning. Sounds like something is wrong with the pivots, everything about them should be investigated, cleaned and adjusted for smooth motion. For the alt. movement when the clutches are tight, I'd suggest checking the bolts that hold the alt trunnions to the ota; if they're loose, the scope will move up and down when the clutches are tight, as you describe.

I think your job is going to be to find and adjust tolerances everywhere. Doing so should get the scope working better, if not perfectly.

I know it's frustrating. But know this: The vast majority of scopes that I've bought (30 or so) have required tweaks at best, overhauls at worst, to get them working as desired. Maybe this goes away with top-end brands, but it's certainly typical of my experience with lower-end products.

Hopefully others, who have direct experience with this scope, will chime in. I bet you can fix everything. Sending it back to Orion would be a huge PITA.
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#6 pstarr

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Posted 22 July 2014 - 01:39 PM

There are numerous threads on here about tweaking and modifying Orion Dobs. They rarely, if ever come from the box without problems. Do some research on what others have encountered and their modifications and fixes. Your scope is not a lemon, just a typical commercial, quickly put together Chinese Dob. I'm sure you will have it working well soon. Orion customer service is very good. They will replace any parts not working right. Hang in there. Your not alone. By the way, the secondary should not be centered but offset. It is offset in the correct direction in your photo. Research some threads on collimation. The metal in the gears is most likely from the manufacturing process. It most likely was just not properly cleaned before assembly.
read some here for example
another
collimation

#7 Starman1

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Posted 22 July 2014 - 02:31 PM

Hi all,
First issue was that the screen in the hand controller was dislodged internally so that it was crooked, and some of the bottom line of text was cut off. Second issue was that the focuser grinded badly mid focus, to the point it would get stuck sometimes. so a couple days ago I took it upon myself to open up the hand controller, re hot-glue the screen in place (it was hot-glued from the factory but broke loose) and I also disassembled and tuned the focuser so that is also good now. Not pleased with having to do this on my new $2100 scope, but whatever. (And I realize it's not a $15K obsession or something like that, but $2100 is still a substantial chunk of my change lol). I neglected to take photos of the hand controller before I fixed it.

So, in essence, the hand controller is fine now, and the focuser is properly adjusted. Sounds good. ALL focusers need adjustment when they come from the factory. It's as necessary as collimation, but only needs to be done once.

I also noticed that the scope does not track smoothly. I know this is not a $1500 GEM mount with a clock drive, and it uses a pair of steppers which are inherently 'notchy', but it seems more like the scope sticks then moves a bit, especially noticeable at anything at or below 10mm (152x). Posted here about it, folks said it didn't sound normal, I said I would get it on video which I did and will link to below.

This is because the level of roundness, or trueness of the gears and shafts is not perfect. Every time gears engage, they have high spots and low spots. If adjusted perfectly to the low spots, the high spots will grind and stick. The process of adjustment is one of finding the high spots and perfectly adjusting the gear engagement for the high spots. It will result in a little gear slop (called backlash) in the low spots, but the alternative, high precision, would run the cost of the scope way up.

Another thing I noticed was that with the clutches loose (fully), the azimuth motion is super loose as expected, however the alt motion is still sticking like the clutches are dragging or something else is going on. The scope does not freely pivot on the alt axis, as is actually specifically mentioned in the manual that it should.

Then the clutch is not completely disengaging and needs to be adjusted to loosen a trace more. You are moving gears when it is disengaged, so it will never be completely free in its motion, but you should not feel the gears dragging.

Last night I pulled the plastic cover off of the alt sensor/motor unit. I found aluminum metal shavings on and in the drive gear, and also in the plastic gear teeth that turn the position sensor. Photos below. I do not think this is normal.

It is not normal. The gears were engaged too tightly, and, from your picture, you have cracks and chips taken out of the teeth on the gears because of that. At the very least, the gears with the chipped teeth and with missing shavings should be replaced. The factory did not properly adjust the gear engagement.

Additionally, I have been having a hard time getting everything completely concentric in collimation. I like to think I know what I am doing but who knows... Anyway, it always seems like the secondary image is offset from the center of the spider crosshair. Looked more carefully at this today and it seems like maybe the secondary is not properly attached to it's holder at it's center, but rather offset a bit. Photos below, again.

This is normal, and all images should be concentric EXCEPT the shadow of the secondary mirror. You need to read a little more about collimation. Here is a tutorial:
http://www.cloudynig...hp?item_id=2677
There are plenty of illustrations of what you see.

Almost done..... I also noticed this morning that two of the spider vanes are a bit bent, twisted where they attach to the secondary holder. Without forcing them back into shape, which I have not done yet, it is impossible to get the spider to be completely perpendicular to the scope axis, due to the twist some part is always offset and 'wider' than it should be in the optical path.

Check to be sure each spider vane attachment screw is the same distance from the upper end of the tube. If they are not, hopefully the screw holes are larger than the screws. Loosen them and try moving the low one up and the high ones down until they are equidistant from the end of the tube. Then tighten them down until the spider vanes emit a high pitch when plucked. If the tube starts dimpling, put fender washers under the screw heads to distribute the stress over a larger area of tube. The tubes in these scopes are quite thin and easy to dimple before the spider is tight.
It may be necessary to elongate one hole to make all the attachments equidistant from the end of the tube, but maybe not.
You can also make sure the spider vanes are straight by looking at them in the collimation tool. You can rotate them until they are very thin to make sure they are in line with the tube.

And finally, this is more of a question as to normal behavior than a gripe, the scope has a good amount of free play in the altitude axis even with the clutch completely tight. In other words, when the clutch is locked, I can still move the scope up and down a couple inches at the secondary end before it encounters any resistance.

While you won't be able to eliminate this completely when the gears are engaging at the low spots (this is backlash), it will seem to go away if the gears are at their high spots of engagement. If the play is still there, when the gears are replaced, then the clutch may be loose and have a lot of side play, or there may be a lot of play in the motors.
It is not abnormal to have some play as long as the weight of the scope rests on one side of the gear teeth. The test will be in the accuracy of finding and/or tracking.

I need to know what I should do here. I am going to contact Orion, but first I want to quickly pick your brains, especially other Orion GoTo Dob owners, as to how this all relates to what you have experienced with your scopes. What is normal and what is not?

Yes, you have some bones to pick, but they are all solvable. I wouldn't worry about the hand controller or focuser any more, but I would get replacements for the gears. And I would spend some time finding the high spots and adjusting the engagement. Perhaps Orion may have a tech paper on how to do just this. Your pictures are quite concerning, and it is obvious the gears are damaged. In one pic, it looks like one of the gear teeth is ready to break off; in another the gear teeth are damaged.

Thank you, pics to follow in posts below. I will likely ask Orion to reference this post when I call or email them so please keep it as constructive and fact oriented as possible.

Thanks!

Hope that helps.
Don

#8 KerryR

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Posted 22 July 2014 - 03:03 PM

Really nice, thorough post, Don. I don't even have this scope, and I still enjoyed reading it!

#9 twoballscrewball

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Posted 22 July 2014 - 03:32 PM

excellent information everyone, Don thanks for that huge detailed reply it really helped. I sent email to Orion asking them to just take a look at this thread and the photos I attached. I'll let you know what they say. I'm going to take a better look at that spur gear and if there is significant damage I'll ask them to replace it. as far as backlash I know I where there is at least one spot on the azimuth motor where you can hear the gears tighten up and the motor slow down as it turns. Just one spot out of the entire 360 degree range and I know where it is. The altitude motor has never sounded like it was straining in any way.

#10 Billytk

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Posted 22 July 2014 - 03:46 PM

I would have Orion replace the entire base.

#11 GeneT

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Posted 22 July 2014 - 04:58 PM

I have not ever owned an Orion Dob, but I have owned several Dobs over the years. I believe all the issues you addressed are minor. The one that worries me is the metal shavings you found from the gears. I would stop using the item housing the gears until they are replaced.

#12 herrointment

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Posted 22 July 2014 - 06:00 PM

Another home run by Pensack!

How about that!

#13 bluesteel

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Posted 22 July 2014 - 11:53 PM

I have used a newer model, like yours, of an xx12g, and the tracking that is on the YouTube video is not normal. It looks like it is jumping, rather than smoothly tracking. I also own an older model of an xx12g, and the tracking issue you have I do not have either. If the spider veins can not be loosened/tightened to remove the torsion present as well, that would be another issue.
The newer model of the xx12g I have used tracks like butter, once the proper tension is applied to the "wheel" like tension adjustments. It keeps the object in the field of view for an 8mm, 72 degree eyepiece, for well over 45 minutes once alignment is done, as well as adding other stars to the alignment after the initial alignment...
In order to do that, you pick a star or object in the database, get it to slew to that object, then once it has finished and beeped at you, hold down the escape key for several seconds. The screen on the hand controller will then ask you to realign the object it has just slewed to. Get that sucker perfectly centered, and then hit enter. From then on out that, night, all objects around that area should be able to be slewed to through the goto routine without having to use a low power, wide field eyepiece to get the object in the field of view.
Good luck, and let us know how it goes.

#14 Miliu

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Posted 23 July 2014 - 02:41 AM

I have an 8 inch Skywatcher Goto dobsonian, which I think uses the same tracking system as your Orion, and tracking is very smooth even at 240X. If properly aligned the object will not move from the center for a few minutes. Definitelly something is wrong with that mount.

#15 twoballscrewball

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Posted 23 July 2014 - 08:13 AM

Thanks everyone for all the help.

Haven't heard back from Orion at all, which is disappointing.

However, I did some more work on the scope last night and things are looking way better. Pics and details to follow. I am going to make this as detailed as possible with many pics so anyone in the future that stumbles across any of these issues has at least a starting point.

#16 twoballscrewball

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Posted 23 July 2014 - 08:20 AM

Here is the altitude motor/encoder/gear assembly with the cover off, and all the scary aluminum shavings.

Posted Image

To disassemble, first loosen the two set screws on this threaded collar pictured below, then use a 20mm wrench to remove this collar. In my case, this was EXTREMELY tight, and this was the cause of the 'sticky' alt motion even with the clutch released, as this collar was effectively keeping the clutches tensioned at all times. Once this was loosened, the alt dovetail spun freely as expected.

Posted Image

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#17 twoballscrewball

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Posted 23 July 2014 - 08:25 AM

Next the thrust bearing comes off, this consists of two pressure plates and a center roller plate.

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This is the plate that sits on top of the spur gear. Just slides off.

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Next is the spur gear.

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This is the friction plate. Be extremely caareful no not get any dirt / grease / oil / etc on this. Should be dry.

Posted Image

And finally the inner pressure plate, where the friction disc rides. The spur gear is the other half of this system.

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#18 twoballscrewball

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Posted 23 July 2014 - 08:26 AM

the threads on my center shaft were galled up a bit, looks like perhaps some shavings got in the threads. I was able to clean this up easily with a file and an xacto knife.

Posted Image

#19 twoballscrewball

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Posted 23 July 2014 - 08:28 AM

here is where I fixed the next problem I identified, these four socket head bolts were completely loose. They hold the altitude bearing / trunnion on the motor assembly. Once I tightened these, all of the 'slop' in the system was gone, there was now zero free movement once the clutch knob was tight. Made sure these were good and tight.

Posted Image

#20 Pinbout

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Posted 23 July 2014 - 08:30 AM

the threads on my center shaft were galled up a bit,



all these issues are really appalling, and if they don't correct it...everyone needs to know.

thanks for showing us these issues.

#21 twoballscrewball

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Posted 23 July 2014 - 08:32 AM

Next up, the gear mesh. Assuming it was set too tight based on the shavings present, I backed off the tension bolt abuot 2 turns. This system applies constant spring pressure to the spur gear / worm gear mesh, so the spring adjustment does not set a gap, it sets the amount of force that is applied to the spur by the worm. Also upon reassembly I applied a light coating of black moly grease to the spur and worm teeth.

sorry, didn't realize this pic was so bad when I took it.

Posted Image

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#22 twoballscrewball

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Posted 23 July 2014 - 08:43 AM

When reassembling, I took great care when reinstalling the threaded collar that pre-tensions the alt bearing and clutch. Too loose, and the scope did move very freely, but too freely in my opinion, it would be too easy to accidentally damage it and the balance had to be perfect or else the scope would not stay put. too tight, and it was difficult to operate the scope manually by hand.

I put the scope on the base and slowly adjusted this collar until I found that magical buttery smooth sweet spot where the scope would glide up and down with the touch of a finger, but still stay put when released and would slowly stop on it's own if it was pushed and let go. Once found I tightened down the set screws and put the cover back on.

#23 Starman1

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Posted 23 July 2014 - 08:50 AM

Hmm.
The altitude gear will never turn more than 90 degrees or so.
Ergo, if you position that gear, before tightening, so that none of the damage teeth will ever engage the drive gear, you may not need to replace that gear at all.
Thanks for the pix.

#24 twoballscrewball

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Posted 23 July 2014 - 08:53 AM

Freewheel motion after the fix, before the scope had to be dragged up and down with force, it now glides effortlessly wherever you point it, and stays there. :)

http://youtu.be/O8mvXdUtJeo

#25 twoballscrewball

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Posted 23 July 2014 - 08:56 AM

Don, I cleaned and thoroughly inspected the gear. I could not find any substantial damage. Some teeth were mildly marked up on the edge surface, but a lot of what was in those initial pics was just grease / shavings / etc that cleaned off. I had the same thought as you about the gear positioning, but unfortunately it was after I had removed the gear already so I had no idea what part was previously in contact with the worm, after I cleaned it up no one part of the gear looked any worse than any other. I did sit and watch and listen to the gear make full rotations in both directions with the cover off (patience is a virtue lol), there were no points that looked or sounded like there was anything bad happening so I think the gear is OK.






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