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Mach1 Remesh

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#1 JumboFlex

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Posted 24 June 2013 - 07:46 PM

Hi.

Decided to remesh my Mach1. I followed APs instructions very carefully and while the gearbox did loosen it did not really allow for much play. So, even though I rocked the gearboxes in an attempt to remesh the gears, given the small amount of play in the boxes I am not sure anything was accomplished. I wasnt going to take the risk of loosening things too much and given that I followed APs instructions closely I figure that such small gearbox movement is perhaps normal. Is it? Thanks for any info anyone can provide.

#2 Calypte

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Posted 24 June 2013 - 09:53 PM

Have you tested it? The Mach1 doesn't come with PEMPro, but it'll be well worth buying the program if you don't already have it. That way you can test the effect of the gear-mesh adjustment. If you followed the directions, you should be OK. The gear box won't rock too much when the screws are loosened as per the instructions. You're just trying to be sure the worm is correctly seated on the worm gear as you tighten the screws. I can tell you from personal experience that the correct mesh is critical to getting the best PE. If you're unsatisfied with the result, then try again. With my Mach1, the PE wasn't even close to spec until I got the gear mesh right.

#3 orlyandico

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Posted 24 June 2013 - 10:33 PM

in my case the worm gear was meshed too tightly and caused the CP3 control box to get really, really hot.

so i followed the manual and remeshed. the PE didn't change much (it was about 5" p-p in both cases).

#4 JumboFlex

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Posted 25 June 2013 - 10:24 AM

I dont image so PEC isnt critical for me nor do I test for it. I had just read some reports about how remeshing may reduce the noise during slewing so I figured I would try it. I was just curious as the gearboxes didnt seem to come loose enought to allow enough movement to reseat the gears. Havent had a chance to see if it actually made a difference noise wise.

#5 Calypte

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Posted 25 June 2013 - 11:02 AM

I haven't found much difference in noise at any setting reasonably close to the "ideal" setting. I certainly wouldn't mess with a mount that's still operating satisfactorily at the factory setting. Eventually, the mesh may loosen up a bit, resulting in a bit of backlash. At that point it's appropriate to reset the gear mesh. That's based upon a sample of one -- my Mach1GTO.

Edited to add: Be sure to sign up on the AP-GTO forum on Yahoo! Roland, George Whitney and Howard Hedlund from A-P are regulars in the forum, plus lots of other A-P mount users. Any question you can think of can be answered by the best experts.

#6 orlyandico

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Posted 25 June 2013 - 11:54 AM

slew at 600X for a decent noise reduction.

#7 Doug D.

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Posted 25 June 2013 - 12:27 PM

Excuse my ignorance but under what circumstances would you need to consider time is right for a remesh? I checked my manual last night and it only seems to say that remesh is one of the few maintenance items you may need to do but it doesn't suggest when. Is it a change in PE or just an expectation that it will loosen with use and need to be remeshed and "tightened? I'm sticking with the "if it ain't broke....." strategy for now of course.

#8 Calypte

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Posted 25 June 2013 - 12:48 PM

It's "broke" when the PE gets too high or backlash develops. I agree -- if it's working well, don't mess with it. It's easier to get the mesh out-of-whack than to get it right again.

#9 M13 Observer

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Posted 25 June 2013 - 07:27 PM

Excuse my ignorance but under what circumstances would you need to consider time is right for a remesh? I checked my manual last night and it only seems to say that remesh is one of the few maintenance items you may need to do but it doesn't suggest when. Is it a change in PE or just an expectation that it will loosen with use and need to be remeshed and "tightened? I'm sticking with the "if it ain't broke....." strategy for now of course.


Grab the CW shaft and gently push / pull on it back and forth. If it easily "rocks" or "clicks/clacks" as it is moved to and fro, the mesh needs to be tightened up as per instructions on the AP Tech portion of their website. Otherwise just use it.

#10 Doug D.

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Posted 25 June 2013 - 08:15 PM

Thanks guys - I'll check next time I set up but I think I'm good for now.

#11 Raginar

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Posted 26 June 2013 - 12:03 AM

Backlash was the reason I used to adjust my MI-250's gear mesh. Cleared it up.

#12 orlyandico

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Posted 26 June 2013 - 05:09 AM

Remesh on a mach1 is a dead simple operation compared to the other mounts I've had and tried though.

#13 BlueGrass

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Posted 26 June 2013 - 08:48 PM

Agreed. The instructions are easy to follow. Both motors mounting are designed for easy access and adjustment.

#14 AndreyYa

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Posted 02 July 2013 - 04:57 PM

Gents,

should this DEC tracking curve be the reason to remesh my new Mach1's DEC worm? The scale was about 2" per pixel (FL 510mm, guiding with QHY5 camera 7 sec exposures), so DEC RMS error is about 0.5". Scope was more or less balanced.
I'm pretty happy with my current tracking, but I'm afraid it will not fit with guiding 1000-1200mm FL imaging scope.

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#15 korborh

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Posted 02 July 2013 - 06:58 PM

How do the guided stars look in the image? Are they oblong in the DEC direction? If the stars are small and round, I would not mess with the mesh of the worm.
The DEC curve could also be due to too tight of a mesh - i.e. stiction. But if the stars are tight and round, why bother?

#16 AndreyYa

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Posted 02 July 2013 - 08:26 PM

How do the guided stars look in the image? Are they oblong in the DEC direction? If the stars are small and round, I would not mess with the mesh of the worm.
The DEC curve could also be due to too tight of a mesh - i.e. stiction. But if the stars are tight and round, why bother?

Hi Korborh,
Actually, I'm happy with current stars shape. Please see attached image: scale 1:1 crop from single 10 minutes exposure of M17 region; no curves, sharpening etc.
I'm just worrying about shooting with longer focal lengths. I had 6+ years experience fighting with tracking using Sirius and Atlas mounts. I had the same chainsaw shaped tracking (but 3-5 times higher amplitude) with these mounts, it happened when scope was not properly balanced on DEC.
Korborh, could you please say, does AP1200 have the same kind of DEC tracking?

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#17 korborh

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Posted 02 July 2013 - 09:35 PM

Hi AndreyYa,
Yes I have seen this type of DEC guiding with my AP1200 but my guider scale is much smaller - 4x smaller than yours. I am guiding at 0.5"/px on the C14Edge.
Unless the errors are too big, for me this type of graph does not correlate with oblong stars. However when I have the mesh on the tighter side, this effect is more pronounced and I can only think of it as stiction. IF then the RA guiding is really tight, then you will small but oblong stars. All this appears if the stars are really small and well focused so effects from less than perfect DEC guiding can show up in the image.

For my mount I have found that the best meshing is the one which is on the verge of feeling backlash - i.e. towards the loose side so that a slight change to it will start showing up as movement on the scope with clutches tight. And that the gear on the worm is very easy to rotate by fingertips. The meshing on Mach1 is perhaps simpler....but this stuff is not hard to do and I would recommend meshing on the loose side rather than tight.

On an AP mount, if your guiding calibration was done correctly, then I suspect that mesh is slightly on the tighter side. And you are probably very well polar aligned that DEC corrections are needed in both directions.

#18 korborh

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Posted 02 July 2013 - 09:41 PM

Your DEC graph does not look problematic to me .... the RA and DEC RMS are also quite similar. So unless you see oblong stars when you see this type of graph, I would not change the meshing.

#19 Calypte

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Posted 02 July 2013 - 10:22 PM

Really, anyone with an issue concerning an A-P mount, especially a new one, should call A-P. Part of the reason you paid all that money for Astro-Physics is their exemplary customer service. Use it! As for the DEC gear mesh, in 3 years of owning a Mach1GTO, I've never had to touch the DEC gears.

#20 blueman

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Posted 02 July 2013 - 10:57 PM

Just a couple of words from me. Guiding will be a direct relationship to the conditions. You cannot get the guiding to be smooth if the conditions will not allow it.

So, if you see poor guiding in your opinion, what are the conditions like?

Have you tried to change your settings? I would set up and just guide and make changes to the setting, min move, max move, aggression and see how it goes.

But if you find that you just are stuck at a certain guide performance then maybe you need to run PemPro and see just what your mount is doing.
Blueman

#21 AndreyYa

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Posted 03 July 2013 - 03:01 AM

Gents, thank you for your comments and answers.

Just to make things clear: I'm happy with current tracking performance of my Mach1. These numbers are hardly possible with Atlas or Sirius: having 0.25'" RMS error for 7 sec guiding exposures. I'm just afraid it will be not enough for 1000-1500mm FL.

I'm still not familiar with PemPro. I analyzed tracking log with PecPrep and didn't see there any suspicious signs. Just in case please see attached PecPrep chart for guided tracking (510mm FL, QHY5, guiding exposure 7 sec). But... it explains nothing regarding DEC tracking.

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#22 AndreyYa

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Posted 03 July 2013 - 03:11 AM

And unguided tracking looks nice as well - about 5" p-p periodics.

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#23 orlyandico

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Posted 03 July 2013 - 04:01 AM

It will be enough. My RMS guiding on my Mach1 is about 0.5" and I successfully was able to do 5- and 10-minute exposures of Cleopatra's Eye and the Eskimo at 2350mm, and 2 minutes on Cleo with a 2X barlow (e.g. 4700mm). This was using a C9.25 so about 30lb of payload and a QHY8, so the pixel scale was 0.68" (at native FL) and 0.34" barlowed.

My RMS guiding never gets better than 0.5" to 0.6" - I think it's the seeing.

Cleo's Eye at 4700mm @ 2 minute subs

Posted Image

Eskimo @ 2350mm

Posted Image

These aren't particularly good images, took them from my balcony with mag 3 skies (!!!) and I didn't use an OAG, just a Meade 60mm f/9 as a guide scope.

#24 AndreyYa

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Posted 03 July 2013 - 04:01 PM

Thank you Orlyandico.
I'll check guiding capabilities for longer focal length with my Mak-Cass, I expect to have about 1200mm FL with reducer.

#25 blueman

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Posted 03 July 2013 - 08:35 PM

And unguided tracking looks nice as well - about 5" p-p periodics.


This all looks pretty good really. 5" PE is good, my AP900 is 6-7" and I image at 740mm and 980mm with great looking stars.
I am sure it could handle long f/l with out a problem.
But as I said before, it is possible that conditions could still be an issue.
Blueman






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