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Equipment Discussions >> Mounts

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Charlie B
scholastic sledgehammer


Reged: 03/22/08

Loc: Sterling, Virginia
Re: Is this performance typical of G11? new [Re: Startraffic]
      #5657710 - 02/02/13 08:49 AM

StarTraffic,

My G11 is working fine. My problem was that both the RA and DEC worms were too tightly adjusted at the factory, resulting in binding. I took both worms off and inspected and adjusted couplers and worms. I now get very good and smooth performance from the mount (about +- 5" unguided PE).

I took Ed Thomas' advice and adjusted the worms, on the bench, while slewing through the entire range.

Now, if I could as easily fix my poor seeing...

Best regards,

Charlie B


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Is this performance typical of G11? new [Re: contraf15]
      #5658049 - 02/02/13 12:31 PM

Quote:

Hilmi congrats on the improvement! I tried my setup tonight with a completely different computer running all of the software. That allowed me to guide throug ASCOM instead of the ST-4 port (no idea why that won't work on my other computer). My graph is below. For reference, this is the STi guiding through SBIG OAG. Scope focal length is 952mm. With the 0.7x reduction of the OAG, the scale is 2.29"/pixel. The graph shows deviation in pixels, so I'm still seeing these crazy >10" jumps. I have now eliminated the computer, guide port, and software as possible causes.

How did you clean the RA axis? I'd appreciate any specifics you can provide.

Jeremy




I'm not great on these graphs, but the error looks random. That suggests that the mount is more or less "dirty" and that is causing most of the error. There can be "grit" on the worm or in the worm and/or axis bearings causing problems like this.

Where this mount not new, the first thing I would do is a good cleanout of the mount. The G11 does not require a lot in the way of tuning beyond the worm spacing, but it does require periodic maintenance. The axis bearings are open needle roller bearings that can get dirty over time. While they can be cleaned in place to some extent, it is best to remove them to really get them cleaned out well. There isn't anything you can do with the worm bearings except replace them.


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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: EFT]
      #5660042 - 02/03/13 01:58 PM

Today I am doing the most brutal test I could think of for my repairs of the mount. I'm doing 20 minute exposures guided, but with wind that is occasionally gusting up to 18 Km/h. The mount is housed in a roll off roof observatory, so it's not getting much wind protection.

I'm just starting the test now, but I did a short trial of 1 minute during gusts and the stars where perfectly round. So I guess if it can keep the stars ROUGHLY round in such gusty winds at 20 minutes an exposure, I can officially declare all mechanical faults fixed.

This test is not fair considering the conditions, but honestly, I don't have to wake up early for work tomorrow and there has been rain in the morning which means transparency is great. I figured I might as well do some random experimentation to see how well my repairs have gone.


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Is this performance typical of G11? new [Re: Hilmi]
      #5660070 - 02/03/13 02:16 PM

Quote:

Today I am doing the most brutal test I could think of for my repairs of the mount. I'm doing 20 minute exposures guided, but with wind that is occasionally gusting up to 18 Km/h. The mount is housed in a roll off roof observatory, so it's not getting much wind protection.

I'm just starting the test now, but I did a short trial of 1 minute during gusts and the stars where perfectly round. So I guess if it can keep the stars ROUGHLY round in such gusty winds at 20 minutes an exposure, I can officially declare all mechanical faults fixed.

This test is not fair considering the conditions, but honestly, I don't have to wake up early for work tomorrow and there has been rain in the morning which means transparency is great. I figured I might as well do some random experimentation to see how well my repairs have gone.




Excellent! It's good to hear that it is working now.


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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: EFT]
      #5660073 - 02/03/13 02:18 PM Attachment (40 downloads)

OK, What do you all think? Should I leave it as is or should I continue messing with the mount? Up down direction in the picture is Dec axis. left right is RA Axis. This is a single 20 minute sub

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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: Hilmi]
      #5660085 - 02/03/13 02:22 PM

Wow, that looks great for 20 minutes! I wish I could get mine doing that.

I'm getting ready to completely strip it down, clean it, and regrease.

Does anyone have a tip for getting the needle bearings out of the axes?

Jeremy


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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: Hilmi]
      #5660089 - 02/03/13 02:24 PM Attachment (33 downloads)

Here is a 1:1 scale capture of the worst star in the image. This is scale according to Pinpoint LE is 1.38"/pixel

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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: Hilmi]
      #5660093 - 02/03/13 02:27 PM

Jeremy, I couldnt get mine out. I just cleaned them in place. I have no experience removing bearings. I suspect my Declination axis worm wheel(not worm gear) bearing is in ill health as it was binding when I looked at it while cleaning, but for the life of me I couldn't see how it could be removed. It fits so snugly and I just cant see how one would pull it out. No more Wahiba sand dunes trips for this mount.

Edited by Hilmi (02/03/13 02:28 PM)


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pfile
Post Laureate


Reged: 06/14/09

Re: Is this performance typical of G11? new [Re: Hilmi]
      #5660115 - 02/03/13 02:39 PM

is that star on the optical center? you should probably look at stars in the center just to eliminate coma or curvature as the cause for elongation.

i actually have some 20min subs with my G11/G2 that have almost perfectly round stars. but they were taken with a 5nm Ha filter, which i think helps. the best ones were taken with an AO-8 running.


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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: pfile]
      #5660128 - 02/03/13 02:45 PM

I thought the LX200R was coma free! Anyway, that star is from 1/4 of the way from the right side of the image. Some of the stars are actually perfectly round. Maybe my camera is not exactly perpendicular to the path of the light. Might be tilted to one side. The stars on the left of the image are definitely more round than the ones on the right. Regardless, I am happy considering it's windy. I guess the true test will be when the wind dies down. I'm coming back from my biweekly business trips Next Thursday, I hope by then the wind would have died down then I can have a fair test. The image was taken with the Baader Ha filter that came with my camera. Can't recall the specs. I don't want to go near the mount while its imaging to rummage through my equipment to find the cases and check the specs.

Next week I am also getting my pier adapter. And the mount should be mounted on a solid steel 6" diameter pier.

Edited by Hilmi (02/03/13 02:48 PM)


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EFT
Vendor - Deep Space Products
*****

Reged: 05/07/07

Loc: Phoenix, AZ
Re: Is this performance typical of G11? new [Re: contraf15]
      #5660276 - 02/03/13 04:14 PM

Quote:

Wow, that looks great for 20 minutes! I wish I could get mine doing that.

I'm getting ready to completely strip it down, clean it, and regrease.

Does anyone have a tip for getting the needle bearings out of the axes?

Jeremy




Take a long metal rod or wood dowel and from the other end, tap around the circumference of the bearing. Don't hit it too hard lest you damage the bearing. They should slowly move out of the housing. To replace them tap them back in place and then use a socket from a wrench set that it just smaller than the bearing diameter to tap it all the way back down.


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Is this performance typical of G11? new [Re: EFT]
      #5660756 - 02/03/13 09:20 PM

Hilmi, could be mirror tilt as well. Don't know how effective the mirror locks are on the LX200R.

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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: orlyandico]
      #5667952 - 02/07/13 10:07 PM

Another update...I completely disassembled the RA axis and cleaned all of the bearings, the worm wheel, and the worm with acetone. I added a third needle bearing to the scope end of the axis as well. Regreased everything with Super Lube and put it all back together. I ordered a new Ruland coupler and gearbox (just in case) from Losmandy and they shipped out today (turns out they do sell the couplers, they just aren't listed on the website).

I saw on another thread something about a batch of bad worms from late last year, so I emailed Scott a picture of the original RA worm and asked if he could confirm whether there was a known problem with some of the worms. He responded within a couple of hours, and though he didn't confirm whether there was a bad batch of worms he did promise to ship me a new worm and bearings tomorrow.

I'll update once I get the new worm installed. Even though the mount is brand new, the cleaning & regreasing of the needle and thrust bearings made the RA axis turn noticeably smoother with the clutch loosened.

I'm keeping my fingers crossed...


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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: contraf15]
      #5672438 - 02/10/13 02:17 PM Attachment (17 downloads)

I let CCD autopilot optimize my guiding parameters Resisting throwing your gear out the window and keeping on at it is eventually worth it if you have the patience. The numbers don't look as good as the previous post, but everything is very consistent now. No sudden odd guiding behavior. So now I am getting super round stars

Edited by Hilmi (02/10/13 02:22 PM)


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Raginar
Postmaster
*****

Reged: 10/19/10

Loc: Rapid CIty, SD
Re: Is this performance typical of G11? new [Re: Hilmi]
      #5672488 - 02/10/13 02:40 PM

Hilmi, what version CCDAP are you using that it automatically optimizes your guiding settings? Do you have the 'Pro' version?

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Hilmi
Post Laureate
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: Raginar]
      #5672507 - 02/10/13 02:47 PM

Yep, thats the one I have. You put in your focal length. Dont trust your calculations, I found out that my F6.2 reducer was working at f8 because of the spacing etc... I used plate solve from both TheSky X and MaximDL to confirm this. After you put in the specs of your CCD (pixel size) and guide CCD and your focal length you ask it to recommend settings and then tell it to apply to MaximDL.

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Raginar
Postmaster
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Reged: 10/19/10

Loc: Rapid CIty, SD
Re: Is this performance typical of G11? new [Re: Hilmi]
      #5673054 - 02/10/13 08:57 PM

Do you have 5?

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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: Hilmi]
      #5680514 - 02/15/13 12:59 AM Attachment (24 downloads)

Well I'm pleased to report that the new worm and bearings Scott sent are installed, and I completely stripped the mount and regreased it with SuperLube. While I was at it I made my own clutch knob mods because I got tired of waiting for them to be in stock somewhere. The results look good so far. This picture is a screen grab (sorry, probably hard to read) showing <1 pixel deviations now in RA. The image in the back is a single 10 minute Ha frame of the Alnitak region I took tonight as a test shot. Round stars! No halos! Would have been nice if all this equipment had worked out of the box...but I guess that's what you pay for if you get a Mach 1. My next order of business will be to see if I can get Losmandy to fix or replace my G11 hand controller, which has frozen up so much that I have abandoned it for computer control of the mount through the web interface and ASCOM.

But the biggest issue, the heinous RA tracking, appears to be getting better. Maybe now I can get some sleep.

Jeremy


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Is this performance typical of G11? new [Re: contraf15]
      #5680535 - 02/15/13 01:20 AM

That level of guiding performance is very close to what I'm currently getting with my Mach1.... So a very good result.

Of course the difference is the Mach1 did that out of the box...


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neilson
professor emeritus


Reged: 08/22/10

Re: Is this performance typical of G11? new [Re: orlyandico]
      #5680576 - 02/15/13 02:13 AM

Hi Jeremy,
My new mount is plagued with tracking issues. My RA is tracking slow. I am having to weight the West side heavy but that only works for a short time then it slows back down. I would be interested to know what the Periodic Error (PE) of your new worm is. I just got my replacement worm and my results are not very good but once my tracking problems are fixed I expect better results.

Thats a great looking image.

neilson


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