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Equipment Discussions >> Reflectors

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Jarrod
Pooh-Bah
*****

Reged: 01/20/13

Loc: SE USA
Re: Potential vibration issue with tracking? new [Re: Starman81]
      #5943048 - 06/27/13 12:39 PM

I may have noticed this for the first time the other night. The conditions were:

a) Viewing an object near zenith.
b) High magnification
c) A heavy EP installed
d) Scope not sitting on level ground

In particular, (d) is something that I had not done before. I was setup on the sidewalk in the front yard and we live on a reasonably steep grade. Based on the fact that I have not noticed this before, but have viewed with at least two of the other three variables in place simultaneously, my current hypothesis is that the sloping ground was a big contributor.

Edited by Jarrod (06/27/13 12:43 PM)


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Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Potential vibration issue with tracking? new [Re: Jarrod]
      #5944157 - 06/28/13 02:14 AM

Quote:

I may have noticed this for the first time the other night. The conditions were:

a) Viewing an object near zenith.
b) High magnification
c) A heavy EP installed
d) Scope not sitting on level ground

In particular, (d) is something that I had not done before. I was setup on the sidewalk in the front yard and we live on a reasonably steep grade. Based on the fact that I have not noticed this before, but have viewed with at least two of the other three variables in place simultaneously, my current hypothesis is that the sloping ground was a big contributor.




The conditions when I observed it compared to yours were quite different, see below in italics:

a) Viewing an object near zenith. - nope I had it on Saturn which we all know doesn't rise very high at all at this point in time.
b) High magnification - I was only at 171x, that is more like medium-high
c) A heavy EP installed - the EP was Pentax XW 7, relatively not a heavy EP
d) Scope not sitting on level ground - scope was on a level sidewalk

I had a very short session a few nights ago, but the seeing was so bad that star images were jumping all over the place, tracking on or not. Still waiting for a decent night that I am able to observe to make some more observations in regards to this supposed problem.


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Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Potential vibration issue with tracking? new [Re: Starman81]
      #5973083 - 07/15/13 08:39 PM

I am still looking for a night with good seeing and one that I can actually get out early enough to get my scope acclimated in order to investigate the 'jumpiness' in my tracking. I had a session a few nights ago that more or less had the same result, so I am kind of bummed for now, but really hoping for a fix/mod/adjustment of some sort. There are plenty of other XTg owners out there and I have never read of this type of issue yet, so I am hoping it is resolvable. This time around, I was using 184x on the Wild Duck Cluster and could see bright stars at the edge of field bouncing around. Turning off the fan did help a bit, so I am still looking to see how much that is playing a part.

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dan777
scholastic sledgehammer
*****

Reged: 11/16/07

Loc: Indiana
Re: Orion XT*g tracking new [Re: LunarRover]
      #5973297 - 07/15/13 11:06 PM

Quote:

Would like to get some input from owners of the Orion XTg goto dobs, if you've had issues with motor induced vibrations causing image "bounce", especially with high power viewing, as mentioned in the S&T test report?

Also, has goto accuracy been satisfactory?



My XT8g as delivered had a very noticeable stepping motion in ALT movement. It was obvious at 170x. Orion replaced the scope.

The goto accuracy is excellent. My XT8g is more accurate than the Intelliscope I used to have.


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TexasRed
scholastic sledgehammer


Reged: 05/17/11

Loc: East Texas
Re: Orion XT*g tracking new [Re: dan777]
      #5973649 - 07/16/13 07:08 AM

The fan shouldn't make the view jittery either. I can't tell when my fan is running. Orion needs to take that one back and replace it. There's something seriously wrong with it that isn't wrong with the others.

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Chaz659
sage


Reged: 12/08/12

Loc: Islip, NY
Re: Orion XT*g tracking new [Re: TexasRed]
      #5974601 - 07/16/13 04:54 PM

Quote:

The fan shouldn't make the view jittery either. I can't tell when my fan is running. Orion needs to take that one back and replace it. There's something seriously wrong with it that isn't wrong with the others.




I would have to agree. This thread started more than a month ago and there has been nothing resolved. I would begin the process of requesting a replacement. I have been doing a great deal of reading regarding these scopes, here and other forums, and I am sorry to say I have never seen anyone with this issue, therefore haven't seen a way in which to resolve the problem either. Get it replaced. Best of luck and please let us know how things work out for you.


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kharrison
member


Reged: 10/16/12

Re: Orion XT*g tracking new [Re: Chaz659]
      #5975016 - 07/16/13 09:04 PM

I have started having the same trouble with my XX16g. In my case I was using high power (300x). It was on the grass but I leveled it with shims. The eyepiece was a 6mm Delos, which weighs 1 lb. I was at a public observing event so I didn't have much time for testing. Since I bought it through a telescope store here in Dallas and it is still under warranty I just dropped it off with them. I'll post something as soon as they get back to me.

BTW, has anyone besides Dan contacted Orion about this?


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Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Potential vibration issue with tracking? new [Re: my_universe]
      #5975816 - 07/17/13 11:35 AM Attachment (8 downloads)

Quote:

Check to see if the right side bearing on the OTA is rubbing agaqinst the right side panel. There should be a small gap of a couple millimeters at least. If it is rubbing, that could be causing some stiction, resulting in jumpy tracking. Some lithium grease or graphite powder between the two parts might solve it, or you could add a thin shim (maybe 1/16") between where the right side panel attaches to the front panel, as this would move the right side panel slightly outward, creating the needed gap.




Well, you were right--the right side bearing IS rubbing against the right side panel. Not all the way around but towards the back, definitely. On the front side there is a healthy gap of 2-3mm at least. I don't have any shim stock on hand, how about some double-sided foam tape between where the right side panel attaches to the front panel, that should work I think (?).


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kharrison
member


Reged: 10/16/12

Re: Orion XT*g tracking new [Re: kharrison]
      #5978702 - 07/18/13 09:16 PM

Well, it turns out there was a considerable amount of west Texas regolith contaminating the grease in my drives (mainly azimuth). The guys at The Observatory cleaned it up and put in fresh grease. They tested it as best they could in the store but I'll have to take it out someplace to be sure. We also checked the gap on the right alt bearing and it was clear.

Anyone else with this problem go to TSP this year?


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thetortoise
super member
*****

Reged: 07/25/12

Loc: Longmont, CO
Re: Potential vibration issue with tracking? new [Re: Starman81]
      #5993851 - 07/27/13 11:07 PM

I am always amazed at how smoothly my XT10G tracks, even at high powers. I always expect to see something from the motors but I never do. On the other hand, when I don't have the tracking on, and am trying to nudge the thing, that's when the view bounces all over the place.

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Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Potential vibration issue with tracking? [Re: thetortoise]
      #5994053 - 07/28/13 02:09 AM

Quote:

I am always amazed at how smoothly my XT10G tracks, even at high powers. I always expect to see something from the motors but I never do. On the other hand, when I don't have the tracking on, and am trying to nudge the thing, that's when the view bounces all over the place.




Thanks for sharing, Jarad, we need all the data points we can get. I wish so badly that this was my experience as I really do like this scope. Can you check your right side bearing to see of there is any contact? On mine, you could not even slide a piece of paper in i.e. there was full contact.


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thetortoise
super member
*****

Reged: 07/25/12

Loc: Longmont, CO
Re: Potential vibration issue with tracking? new [Re: Starman81]
      #5994665 - 07/28/13 12:34 PM

I had never checked this before but I can confirm that there is no contact on the right bearing. A thick card-stock slipped right in there no problem with room to spare. Ok, potentially really bad idea, but what if you just sort of pulled outward on the right side to loosen it up? A bit of mechanical manipulation "might" work (just don't break it of course...)

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Billytk
Pooh-Bah


Reged: 04/22/12

Loc: Lake Mary, Fl.
Re: Potential vibration issue with tracking? new [Re: thetortoise]
      #5994914 - 07/28/13 02:59 PM

I would try some carnuba wax where it rubs to make sure that is where the issue is. You can always wipe the wax off. If that does solve the issue then you can either keep the wax there or find a way to loosten the gap.

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Jeffgg
newbie


Reged: 07/30/13

Re: Potential vibration issue with tracking? new [Re: Starman81]
      #5998536 - 07/30/13 02:18 PM

Starman, were you able to correct the bearing issue? I was about to purchase a XT10G but now a little apprehensive....
Best luck


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Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Potential vibration issue with tracking? new [Re: Jeffgg]
      #5998827 - 07/30/13 05:29 PM

Jeff, welcome to Cloudy Nights! Though we've had a nice stretch of clear nights recently, work and life combined have kept me away from observing. I have applied the mod of adding a shim in between the front and right side panel and did indoor testing. With just that 1/16" shim in place, the bearing *eventually* ends up moving back into contact with the right side panel. I will double that thickness up and see if the result is better, but keep in mind, it has not been concluded yet that this is the cause of the jumpiness in tracking.

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Starman81
Carpal Tunnel
*****

Reged: 03/06/08

Loc: Metro Detroit, MI, USA
Re: Potential vibration issue with tracking? new [Re: Starman81]
      #6054309 - 08/30/13 12:10 PM

I've had a few opportunities now to test the scope out further. The 1/12 inch shim did not make a difference and even when I move the OTA ever so slightly to make sure that the bearing was not touching the side board, there was still vibration. I guess is just something you have to live with. It can be exacerbated by poor seeing and thermals, but when those two issues are at bay, the tracking is "good". Now Saturn is a bit too low or already has set by the time I am able to observe nowadays, so high power planetary testing can't be done, but I had the Moon at 144x with BV'ers and there was no noticeable vibration.

So overall, I have not quite nailed down the cause. But I will still test with perhaps adding weight to the base or maybe adding to the shims and re-test, in case my first test was flawed and then I'll try whatever else comes to my mind. But I won't worry sooo much about it. While using this scope, I've had a lot of fun. It combines the capability of my XT8i and Nexstar 8SE in one tidy package (those two scopes are gonna hit the selling block!). I find the software/controller on this unit is more user friendly than either the XT8i or the 8SE (though not perfect) and doing the alignment is a snap. Even if I have to turn off the tracking and 'hand-track' with the controller for high-power planetary/double star observing I am ok with that since I am mainly a DSO observer anyways and this scope does well in that regard.


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