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Equipment Discussions >> Mounts

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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Is this performance typical of G11? new [Re: Hilmi]
      #5649635 - 01/29/13 02:06 AM

Hilmi, buy the kit and DVD from Ed in lieu of a consulting fee.

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Hilmi
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Reged: 03/07/10

Loc: Muscat, Sultanate of Oman
Re: Is this performance typical of G11? new [Re: orlyandico]
      #5649646 - 01/29/13 02:25 AM

Unfortunately there is no Kit for the G11. He sells lots of other bits and pieces that will be of use to me Next time I need something, I'll first check if he sells it before looking anywhere else.

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orlyandico
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Reged: 08/10/09

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Re: Is this performance typical of G11? new [Re: Hilmi]
      #5649652 - 01/29/13 02:37 AM

i ended up buying the DVD for the CGEM. i suppose the tips will prove handy for my AP600. had the same problem as you - shipping the AP600 to Ed would cost me $450 each way.

speaking of which.... there's some terrible DEC stiction on my AP600. i spent over a year fighting it and in the end gave up and got a Mach1.

now the AP600 sits there accusing me i'm hoping with Ed's DVD and some bearing scraping i can fix the declination. the RA is fantastic on the thing.. if i can fix the DEC i'm sure it will perform very well...


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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: Is this performance typical of G11? new [Re: contraf15]
      #5650006 - 01/29/13 10:30 AM

Quote:

While I had the worm block disassembled, I decided to inspect the worm itself. I found an area on it where it looks like the threads are actually damaged. You can see it on the attached pictures, though it doesn't show as well in the pictures as it does looking at the worm. I don't know if this is significant enough to affect tracking, and the sides of the threads (the part that contacts the teeth on the RA gear) look fine. But just to be sure, I decided to check out the DEC worm. It was perfect. No visible flaws. I swapped the worms and the gearboxes on the two axes. Still not the end of the story...




It actually shows quite well in the picture. That worm is trashed. The damage is right in the area that the worm rides on the wheel and it is significant. It would be a periodic error, but it would be huge. In addition, if there is that damage, then there is likely additional damage like the worm not being straight. It takes a lot less damage than that to make a worm useless.

I would definitely replace that worm and if it still under warranty I would show them the picture and ask for a replacement.


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Startraffic
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Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Is this performance typical of G11? new [Re: contraf15]
      #5650185 - 01/29/13 12:17 PM

Contraf15,
Oh yeah that worm is bad & needs to go back. I can possibly even tell you how it got that way. Look at the RA gear very carefully. I'll bet the axis "jumped across the worm at some point from not having the clutch tightened up during balancing, & the Worm not having enough "bite" to hold it in place. DAMHIKT IIRC the anodized aluminum is harder than the brass worm & chewed it like a file. Check the RA gear for damage as well, I "should" be ok but....

Clear Dark Skies
John
39.138274 -77.168898


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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: Startraffic]
      #5650250 - 01/29/13 12:50 PM

Thanks Ed and John for the replies. I'm going to send a picture of the worm to OPT and see what they say. I have been very careful with the mount (with the exception of the coupler buffoonery) and I know that the damage didn't happen here. I suspect it happened at the time of the sloppy one-piece worm installation.

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Hilmi
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Re: Is this performance typical of G11? new [Re: contraf15]
      #5650308 - 01/29/13 01:19 PM

Contraf15, I tried tightening the coupler I also have a bearing that felt a little rough so I moved it to the dec axis. Cant test anything, its cloudy.

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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: Hilmi]
      #5651785 - 01/30/13 08:34 AM Attachment (27 downloads)

OK, finally had some clear skies last night to test things out.

The short version: I am ready to throw this thing in a lake. My CGEM tracked better than this.

After changing the RA worm, gearbox, and bearings, I continue to get trash results with RA tracking. Deviations were on the order of 10-15 arcsecs, and they were quick (unable to guide them out). I tried guide exposures anywhere from 0.5 secs to 4 seconds in an effort to get in front of whatever is causing the problem, but no luck.

The deviations appear to be periodic, on the order of every 120 seconds or so which corresponds to half the worm cycle. But this is with a completely different worm than before! I honestly don't know what could even cause such behavior. I am out of ideas, other than return the silly thing. But I don't know what part of it is defective.

Any suggestions?

Jeremy


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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: contraf15]
      #5651792 - 01/30/13 08:38 AM

Same results with PHD by the way, tried that too.

Jeremy


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freestar8n
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Reged: 10/12/07

Re: Is this performance typical of G11? new [Re: contraf15]
      #5651868 - 01/30/13 09:23 AM

I don't know what the problem is - it could be inside the gearbox - I don't know, but something that fast would be best studied with video. If you have a web-cam or video camera you can connect to the telescope, you could use MetaGuide (free, my software) to study the behavior of the star in detail onscreen, and even record its position at video rate. It may give insight into the cause, but either way would be interesting to see.

I don't know if you are showing a passive log or a guiding log - but the star appears to stop and "catch" - then suddenly snap forward. I may be misinterpreting it though.

Anyway - something this fast would be helped by video, and there is free software for the purpose.

Frank


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Startraffic
professor emeritus
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Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Is this performance typical of G11? new [Re: freestar8n]
      #5651948 - 01/30/13 10:05 AM

Jeremy,
PM sent.

Clear Dark Skies
Startraffic
39.138274 -77.168898


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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: Startraffic]
      #5652271 - 01/30/13 12:57 PM

Hi Startraffic,

For some reason I didn't receive the PM. Can you resend?

Thanks,

Jeremy


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Startraffic
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Reged: 02/12/06

Loc: Lat. 39.143345, Long. -77.1748...
Re: Is this performance typical of G11? new [Re: contraf15]
      #5652283 - 01/30/13 01:04 PM

Jeremy,
On its' way
Clear Dark Skies
Startraffic
39.138274 -77.168898


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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]
      #5653097 - 01/30/13 07:45 PM

Quote:

OK, finally had some clear skies last night to test things out.

The short version: I am ready to throw this thing in a lake. My CGEM tracked better than this.

After changing the RA worm, gearbox, and bearings, I continue to get trash results with RA tracking. Deviations were on the order of 10-15 arcsecs, and they were quick (unable to guide them out). I tried guide exposures anywhere from 0.5 secs to 4 seconds in an effort to get in front of whatever is causing the problem, but no luck.

The deviations appear to be periodic, on the order of every 120 seconds or so which corresponds to half the worm cycle. But this is with a completely different worm than before! I honestly don't know what could even cause such behavior. I am out of ideas, other than return the silly thing. But I don't know what part of it is defective.

Any suggestions?

Jeremy




I could be that you have the worm spacing too tight. That can cause the worm to catch and spring free and will accentuate imperfections in the worm. I would back off the spacing a little bit and see what happens.

However, if it is not the worm spacing, and assuming that you did not change the motor or the worm wheel, they are about all that is left. A motor problem doesn't seem likely but I suppose it is not impossible. A defectively cut worm wheel is a possibility. Overall, it sounds like it is time for a return. With the damage to the worm, it's hard to say what other damage the mount may have sustained, but when unexplainable things are happening with a mount that is usually better behaved, that tends to suggest that something bad happened to it.


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contraf15
member


Reged: 10/24/09

Re: Is this performance typical of G11? new [Re: EFT]
      #5653121 - 01/30/13 07:55 PM

Thanks for the comments Ed. I did change the DEC and RA motors when I changed the worms. Is there a way to check the worm wheel? Tonight I am going to try guiding with a different camera through the ASCOM driver instead of the ST-4 port like I've been doing. I don't anticipate any change, but I have to try everything. I'll also isolate each cable just in case there is some crazy RF interference or something.

This is really frustrating after dropping almost 12 grand on new gear last month. Maybe I need to take up needlepoint instead.


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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: Is this performance typical of G11? new [Re: contraf15]
      #5653138 - 01/30/13 08:16 PM

Probably the only good way to check the worm wheel is to remove it, clean it, and then look at it under magnification. That is obviously a lot of trouble, but the wheels are interchangeable and not terribly difficult to get at, so you could try trading them out as well.

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korborh
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Reged: 01/29/11

Loc: Arizona
Re: Is this performance typical of G11? new [Re: contraf15]
      #5653174 - 01/30/13 08:42 PM

Quote:

The deviations appear to be periodic, on the order of every 120 seconds or so which corresponds to half the worm cycle. But this is with a completely different worm than before! I honestly don't know what could even cause such behavior. I am out of ideas, other than return the silly thing. But I don't know what part of it is defective.

Any suggestions?

Jeremy




It could also be due to the worm bearing runout. That can cause periodic glitch in tracking as the worm wobbles about the bearing.


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JoseBorrero
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Reged: 09/04/09

Loc: Puerto Rico Island
Re: Is this performance typical of G11? new [Re: contraf15]
      #5653266 - 01/30/13 09:46 PM

I don't know at which focal lenght are you guiding, but It became easy to me to autoguide with the miniguide scope even than OAG.


Quote:

OK, finally had some clear skies last night to test things out.

The short version: I am ready to throw this thing in a lake. My CGEM tracked better than this.

After changing the RA worm, gearbox, and bearings, I continue to get trash results with RA tracking. Deviations were on the order of 10-15 arcsecs, and they were quick (unable to guide them out). I tried guide exposures anywhere from 0.5 secs to 4 seconds in an effort to get in front of whatever is causing the problem, but no luck.

The deviations appear to be periodic, on the order of every 120 seconds or so which corresponds to half the worm cycle. But this is with a completely different worm than before! I honestly don't know what could even cause such behavior. I am out of ideas, other than return the silly thing. But I don't know what part of it is defective.

Any suggestions?

Jeremy




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powerstroke01
professor emeritus


Reged: 06/19/07

Loc: Western Sierra Nevada Foothill...
Re: Is this performance typical of G11? new [Re: JoseBorrero]
      #5653422 - 01/30/13 11:31 PM

OK, I've been watching this thread. I had the same issues. Even worse!
Sent the g11 to ed Thomas got it back and it was flawless.


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orlyandico
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Reged: 08/10/09

Loc: Singapore
Re: Is this performance typical of G11? new [Re: powerstroke01]
      #5653488 - 01/31/13 01:04 AM

i am in no way questioning Ed's service.. but i'd be pretty upset if a $3600 G11 G2 needed a hypertune right from the store...! now if it was an old $1200 non-Gemini G11, or a Synta mount, then it's expected..

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