Re: Just purchased GM811GHD
large wavy or curved Belleville type round spring washers are under the rear clutch knobs of both RA and DEC.
it would be a quality lapse to leave those out of a new mount.? I am surprised to read of that.
see the nice photos and discussion on ?
There is also a small "R4" size Belleville washer at the back of the aftermarket Ovision worm block system.? There is no such washer designed into the Losmandy drive system, but it can be added by the owner with some slight hand work.?
Best, Michael?
On Dec 26, 2017 3:46 PM, " bvalente@... [Losmandy_users]" < Losmandy_users@...> wrote:
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Glenn if you need to loosen the RA to balance just loosen the clutch a little bit.
B
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Re: Just purchased GM811GHD
Glenn if you need to loosen the RA to balance just loosen the clutch a little bit.
B
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Re: Just purchased GM811GHD
@tensor74,
What spring washer are you referring to, Greg? The RA axis on my relatively new G-11G is also a little tight when balancing. I have been looking for a way to loosen it up to make balance easier.
My apologies to the group if this is a little off topic.
Glenn
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Re: Just purchased GM811GHD
I got my new G-11 in July. works great. Only thing is when I balanced it it was tight in RA. Come to find out they never put the spring washer in. so they sent one and has been working fine since.?
Greg S.
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Re: Just purchased GM811GHD
Yes, it is very possible. I purchased my G11 last November, pulled it straight out of the box, set it up, and had only one problem which Losmandy remedied in 3 days. It worked but one of the gear boxes was binding a bit, so he sent me a new one.
I only had to replace it, in about 5 minutes. It¡¯s been working great for a year.
Doug
From: Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Monday, December 25, 2017 9:13 PM
To: Losmandy_users@...
Subject: [Losmandy_users] Re: Just purchased GM811GHD
Wow, this is scary. I still haven't bought a mount, and haven't taken an astrophoto yet. My understanding is that Losmandy mounts are some of the better ones, though not at the pinnacle--but jeez, it sounds like there's no point in buying one unless I'm ready to tear it apart and rebuild it! I know you guys are perfectionists, and this group is all about improving performance. But. . .is it not possible to pull a GM811G out of the box, set it on a non-back-straining mount and take a decent photo? Thanks (and hope I didn't steal your thread).
[Non-text portions of this message have been removed]
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Re: Just purchased GM811GHD
Wow, this is scary. ?I still haven't bought a mount, and haven't taken an astrophoto yet. ?My understanding is that Losmandy mounts are some of the better ones, though not at the pinnacle--but jeez, it sounds like there's no point in buying one unless I'm ready to tear it apart and rebuild it! ?I know you guys are perfectionists, and this group is all about improving performance. ?But. . .is it not possible to pull a GM811G ?out of the box, set it on a non-back-straining mount and take a decent photo? ?Thanks (and hope I didn't steal your thread).
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Re: Ovision worm gear assembly does it have a spring washer...may be mssing on mine
Hi,
Nice to read of your observations and maintenance work.
I suggest that you try to separate what PHD2 is telling you, from how the mount is actually performing.? It would be easy to misinterpret the PHD2 messages.
So I suggest you do the following to diagnose the mount.? The diagnostic will also point to where the worm system problem is, if there is a problem at all.
The diagnostic is the PE measurement itself.? For that, you can use the free program PECprep.exe, which you can download from the EQMOD group.? When you run that program, you first select the mount type as G11.? It has all the right mount parameters built in.
You will also need to select as the input file a clean PHD2 log file.? To get that, find where where on your? PC that your PHD2 log files are normally stored.? Usually they have a simple date code, and they are text files.??
You set up your mount and put your autoguider camera at prime focus of your imaging scope.? Do not use a guide scope...you must eliminate any mechanical coupling issues.??
Point at the intersection of? celestial Meridian and Equator.? Do a very careful drift alignment...the PHD2 has a drift align tool that works well.? You want the guide star to stay in the autoguide camera field for 30 minutes.??
Return to the meridian and equator position and choose a star to ttack.? Allow PHD2 to autoguide to assure it knows N,S,E,W.? Then stop autoguiding and erase or rename the current PHD2 logfile.? You then tell PHD2 to Turn Off guide signals, and start "autoguiding" again.? NowE clean logfile will just have records of the star fluctuations from RA worm motion...the raw PE.? Let that run for about 4 worm periods...which are 239 sec (4 minutes) each.? So maybe let the tracking go for 20 to 30 minutes.
Then rename that PHD2 file with something describing the scope, thd camera, and the date, like G11_SCT_SSAG_Dec_24_2017.txt
Use that in the PECPREP program to analyse the PE.? ?It will tell you the periods that make up the worm PE...each gear and bearing and the worm fundamental, and harmonics, will be shown.? You should hope to get the overall "RMS PE" about 1 arcsec.? If you are near that,? it is about the design limit of the mount.? I show an example near the end of that PDF about improving the G11 PE.??
Anyway...that's my suggestion.
Once you have the mount understood, you can start to set up PHD2 for proper autoguiding.? For that, I find the PHD2 Wizard very helpful.??
All the best, Michael?
On Dec 24, 2017 11:49 AM, " gvblk4@... [Losmandy_users]" < Losmandy_users@...> wrote:
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Thanks Chip
?I took apart the Ovision worm and it does have a spring washer installed
?cleaned and lubed the assembly.
I used an eye loop to look at the worm. There are a few pits in the brass
on the top surface in a few places. I don't think that will cause any issues
Will re-swap Ra? and Dec assemblies.
I have read MIchaels white paper. Considering new bearings and spring washers
On both Ra and Dec although Ovison bearings seem fine upon inspection
While running PHD I noticed I have to keep Agressivenes to 60
and min motion to .25 hysterysus to .35 otherwise Ra is to active.
This is with Dec worm at Ra
I had also tore down both ra and dec and relubed and cleaned up cluth surfaces
Dec had some lube underneath pads. Didn't seem to help Ra performance after
clean and relube of Ra
Greg
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Re: Ovision worm gear assembly does it have a spring washer...may be mssing on mine
Thanks Chip
?I took apart the Ovision worm and it does have a spring washer installed
?cleaned and lubed the assembly.
I used an eye loop to look at the worm. There are a few pits in the brass
on the top surface in a few places. I don't think that will cause any issues
Will re-swap Ra? and Dec assemblies.
I have read MIchaels white paper. Considering new bearings and spring washers
On both Ra and Dec although Ovison bearings seem fine upon inspection
While running PHD I noticed I have to keep Agressivenes to 60
and min motion to .25 hysterysus to .35 otherwise Ra is to active.
This is with Dec worm at Ra
I had also tore down both ra and dec and relubed and cleaned up cluth surfaces
Dec had some lube underneath pads. Didn't seem to help Ra performance after
clean and relube of Ra
Greg
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Re: New G11 mount - loose counterweight shaft?
Ah, you're right, Derek! ?I just did a closer inspection and the play is at the worm gear, NOT at the point where the shaft is screwed in as I erroneously thought at first. ?I played with it a bit by pushing on the mount itself and found the same "ever-so-slight" play. ?It was more obvious originally given that my point of force was further from the axis point.
Ok, I'm sure some play at the worm is expected, so I'm all good, thanks!
Now if the darn power adapter can get here soon I can start exploring the Gemini 2!
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Re: New G11 mount - loose counterweight shaft?
Wes - thank you, although I'm able to thread the shaft all the way in - my situation is the opposite: I'm noticing play between the shaft and the tube which it's screwed into.
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Re: New G11 mount - loose counterweight shaft?
Normal.. The end of the
counterweight shaft is a long way from the center of the RA Axis.. The little
movement you feel is play in the RA Worm..
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Nothing to worry about.. ¡°Ever so slight¡±
is pretty darn good..
?
:-))
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Derek
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toggle quoted message
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From: Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Friday, December 22, 2017
10:43 AM
To: Losmandy_users@...
Subject: [Losmandy_users] New G11
mount - loose counterweight shaft?
?
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Hi all -
I'm new to the forum and to astronomy as well, so pardon the ignorance!
I just received and assembled a new G11 + Gemini 2
system. ?Can't really play with it yet as I didn't realize that the wall
power adapter isn't included, but in the meantime one thing that I noticed is
that the counterweight shaft fees a bit loose when fully screwed in. ?It's
as if the threads aren't super precise and if I push/pull laterally on the far
end a little bit I can feel it move with a ever-so-slight knock at the thread.
?I have the shaft fully threaded in and it feels very snug otherwise.
Normal?
?Anything to worry about? ?Remedies to completely eliminate any play?
Thank you!
Alex
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Re: New G11 mount - loose counterweight shaft?
Alex I found the threads coarse on my CW shaft/ interface. I applied a light coating of lubricant and that helped screw the shaft in all the way.? To date it has not seized/stuck making removal difficult.? Let us know what you learn. Thanks Wes
On Fri, Dec 22, 2017 at 12:43 PM, alextardif@... [Losmandy_users] <Losmandy_users@...> wrote:
?
Hi all - I'm new to the forum and to astronomy as well, so pardon the ignorance!
I just received and assembled a new G11 + Gemini 2 system.? Can't really play with it yet as I didn't realize that the wall power adapter isn't included, but in the meantime one thing that I noticed is that the counterweight shaft fees a bit loose when fully screwed in.? It's as if the threads aren't super precise and if I push/pull laterally on the far end a little bit I can feel it move with a ever-so-slight knock at the thread.? I have the shaft fully threaded in and it feels very snug otherwise.
Normal?? Anything to worry about?? Remedies to completely eliminate any play?
Thank you! Alex
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New G11 mount - loose counterweight shaft?
Hi all - I'm new to the forum and to astronomy as well, so pardon the ignorance!
I just received and assembled a new G11 + Gemini 2 system. ?Can't really play with it yet as I didn't realize that the wall power adapter isn't included, but in the meantime one thing that I noticed is that the counterweight shaft fees a bit loose when fully screwed in. ?It's as if the threads aren't super precise and if I push/pull laterally on the far end a little bit I can feel it move with a ever-so-slight knock at the thread. ?I have the shaft fully threaded in and it feels very snug otherwise.
Normal? ?Anything to worry about? ?Remedies to completely eliminate any play?
Thank you! Alex
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Greg...excellent site indeed!? You're a champ.
Brendan
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Re: Ovision worm gear assembly does it have a spring washer...may be mssing on mine
Hi Greg,
I think that your Ovision's worm gear endplay is not getting set correctly and there is no preload on the worm bearings. I don't have an Ovision worm because the original 2-piece worm blocks loaded with ABEC-7 bearings and Losmandy HP worms were getting sub arcsecond PE numbers after adding Bellevue washers and careful adjustment of the drivetrain and when guided well under 0.5 arcsecond PE from PHD2.?
Have you looked at Michael Herman's article on the G11 drivetrain? If not download it from Yahoo and read it and apply these ideas to your Ovision and you should be GTG. Be sure to clean and relube using SuperLube for long life with minimal separation, gummin up and low viscosity even below freezing. Use SPARINGLY, clean up your clutch discs and be sure to reassemble with the wavey spring washers under the clutch knobs NOT directly on the thrust bearing races. Also do not get hung up on minimal backlash, without a temperature compensated worm gear you will only be making trouble for yourself when the air temps get low enough to shrink the back lash to zero causing stalls.?
Cheers/Chip
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I recently found that with my G11 if the RA worm is too loose or has too much
backlash that I get motor errors lag ....with new Gemini II conroller...So it needs
goldy locks adjustment not too loose not too tight
Also Ovision recommends 1 to 2mm of end play with the allen adjustment
Greg
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Ovision worm gear assembly does it have a spring washer...may be mssing on mine
Hello
In October of this year I bought a used Losmandy G11 with an ovision worm gear.
I am unable to get the performance out of the gear at the RA axis.
I'm getting phd rms numbers of .9 arcsec and 1.0 arsec
After trying many things including 1 to 2mm of end play in the worm by adjusting
the end cap this? did not help. I adjusted both end points of the worm by using
a feeler guage to get even spacing from worm body to mount body. .020 in.
Gear Box to worm gear alignment is fine.
I swapped out motors and gearboxes from dec to ra and ra to dec
No difference.
I then swapped worms. an older dec worm by Losmandy (stainless Steel) to the ra axis and ovison to dec
axis. I now get Ra rns of .59 and Dec of .4 rms
At one time I cleaned all gears and bearings. I took off the end cap of the ovsion worm.
. Is? there supposed to be a spring washer or spring at the end of the OPW at the endcap?
Is there a schematic or drawing showing size if there is supposed to be one.
Thanks for any help and Happy Holidays
Greg
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Thanks everyone for your input.
I have my mount apart inside and I've found a few things. I probably did have the gearbox mounted off-axis when I replaced it the other day.? Inside, comparing the new gearbox with the old one, I can see that the mounting holes on the gearbox, where it goes over the threaded rods coming out of the mount, the holes on the new gearbox are smaller, which explains why I had so much trouble getting it on.? The old gearbox came with the holes slightly enlarged!
I'm enlarged the holes on my new gearbox now, and once I finish the cleaning and regreasing, I'll see how it works once reassembled.
I know about the adjustment on the Ovision worms and I will check that more, but I'm slightly concerned with how rough the RA worm feels now that I have it out, compared to the Dec worm. I'll check whether that is a lubrication issue or a tension issue with the adjustment screw.
Thanks again for all the advice. -Joe
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From your description, I'm pretty sure you have not got your worm axis lined up with your gearbox output shaft axis.??
So when the gearbox shaft turns, it is moving the Oldham pieces, and the gearbox mounting (plastic?) is getting moved back and forth.
So double check the alignment through the Oldham coupler.? Ideally you want that to only rotate, and all in one straight line, not shift the rod parts along the plastic center piece.??
As Brendan says, extra movement of that coupler, particularly at an angle, will put in PE frequencies.? Movement of the rods along the plastic might put in random jumps... all bad for imaging work.?
As I understand it (not having one!), the Ovision system should have a spring washer (Belleville washer) under the far worm end cap. That washer needs to be compressed...somewhat.? See if that is adjusted properly.
Hope you solve this. ..then tell us your story!
Michael?
On Dec 20, 2017 12:55 PM, " brenatlilydale@... [Losmandy_users]" < Losmandy_users@...> wrote:
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Hi Joe
Maybe can turn the worm by hand (with maybe an adapter) to see if the worm has a tight spot?
You can remove the Ra/DEC motors from the mount and run them connected to the Gemini ....just like if they were connected. and test the motor system.? If you still get lags then this needs to be investigated? further.
But since you mentioned issues with the couplings, worm and gearbox, there is probably no issue with the servo motor system.? I'm not a great fan of the oldham coupling but I think it helps smooth out shaft alignment errors, which cause the worm to have various PE errors.
Anyway...FWIW
Brendan
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Hi Joe
Maybe can turn the worm by hand (with maybe an adapter) to see if the worm has a tight spot?
You can remove the Ra/DEC motors from the mount and run them connected to the Gemini ....just like if they were connected. and test the motor system.? If you still get lags then this needs to be investigated? further.
But since you mentioned issues with the couplings, worm and gearbox, there is probably no issue with the servo motor system.? I'm not a great fan of the oldham coupling but I think it helps smooth out shaft alignment errors, which cause the worm to have various PE errors.
Anyway...FWIW
Brendan
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Michael Herman
Doug Bock