Hi nmatxin,
If you already have the brass worm gears installed in your mount you already have high precision worms installed and I highly recommend buying the newly redesigned Losmandy one piece worm block for BOTH RA and DEC axes.?If your mount has the old silver colored standard precision worms then I suggest buying the new Losmandy OPW with a new high precision worm installed and install it on the RA axis and an additional new Losmandy OPW for the DEC axis using your existing worm gear. This configuration will get your tracking PE way down and save you $100 over buying a new pair of HP worm OPWs. If money is not an issue bring your G11 up to the current standard with a pair of HP worm loaded OPWs.?
My thinking is this: the first generation Losmandy OPW may have had slightly higher potential to reduce periodic errors because the old OPW fully aligned the gearbox and worm gears on the same axis to eliminate the very small velocity differences inherent when an Oldham coupler is misaligned, this is inherent to the Oldham coupler design. The potential error improvement was very small but cost TWICE as much as the new Losmandy OPW. IMO the still perfect worm bearing alignment, added ease of worm mesh adjustability and the 50% reduction in cost of the new Losmandy OPW design overcomes the slight loss in potential PE reduction and allows mounts without HP worms on the RA axis (the important axis for imagers) to buy the OPW and HP worm for less than the cost of an EMPTY first generation OPW alone!?
This thinking was proven on my own G11 mount. I had previously tested my standard Gemini 2-mini powered G11 mount with 2-piece worm blocks and HP worms on both RA and DEC axes with a Stellarvue 50mm f/4 guidescope, QHY5L-II Mono autoguider camera and PHD2 doing the honors. I typically saw unguided error in the 3.5-5.0 arcsecond range before I did the usual Losmandy G11 modifications and 0.34-0.5 arcseconds RMS when autoguided. After Scott updated my 15 year old G11 to full current G11G specs with the new tucked-in motors, RA Extension Kit, newly redesigned OPWs and reusing my existing worm gears. The mount turned in slightly better results (3.5 arcseconds unguided and 0.31-0.46 arcseconds RMS guided) using the same QHY5L-II Mono autoguider at the prime focus of a Meade 10" f/6.3 SCT OTA on a very cold night which had my mount lagging severely requiring that I adjust the worm mesh to free up both the RA and DEC axis to test.?
This of course is just one mount but I imaging your results would be about the same.?
Chip
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The moment has come to update my G11?s autoguide. I want to chance the RA (and DEC, perhaphs) worm to achieve a better autoguide. But, my doubt is choose the Ovision option or Losmandy option. Anyone can bring any light about this theme? Thank you.
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Re: Tightened clutch = drag in RA axis of GM-8
Thanks Eric. I could not get it to take a .0015 feeler gauge anywhere, and I held it up to a bright light - no gap visible FWIW. I do have .0010 shim stock at work I could try, IDK, that .004 has to come from somewhere!?
Hopefully I will have time to get it on the arbor press tomorrow and see what happens?
Jeff
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Re: Tightened clutch = drag in RA axis of GM-8
Jeff,?
You might take another look at the bearing housings.? Get a set of feeler gauges and test the gap.? ?It only took 5 thousandths to wreak havoc on my DEC axis.? 5 thousandths might be tough to gauge with your naked eye.??
Eric
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Re: Mount Clutch Tensions
Chip, does one hundred percent of the load applied by the clutch knobs not go through the thrust bearings?
With no scope mounted and clutch loose, so the axis rotates as freely as is possible, does the amount of force needed to rotate not increase by several hundred percent when high tension is applied to the clutch knobs? In my world it does, I guess it's just me.
Jeff
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Re: Mount Clutch Tensions
Remember to balance the Dec (The
Telescope) and then the RA (The Counterweight).. As I just read the G11
instructions.. yet again.. I know they list this backwards..
?
See..
?
Derek
?
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Show quoted text
From: Losmandy_users@...
[mailto:Losmandy_users@...]
Sent: Wednesday, October 11, 2017
2:45 PM
To: Losmandy_users@...
Subject: RE: [Losmandy_users]
Mount Clutch Tensions
?
?
I read
the balance instructions for this Losmandy scope Mount. I have to balance the
RA and the Dec axis's before hand. To ensure a minimal load on the servo motors
during the scope movement. I played with this in the room here and saw what too
loose of a clutch can do. Scope will flip-flop around. Have to be careful not
to damage the scope and hold it with your hand while doing the balancing.
So I sort have a mediocre tension on those. From a 1-10 scale probably a 4 or
5...
Thanks for your input!
Rodney
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Re: Mount Clutch Tensions
Hi Rodney, Bob, and gang,
Bob raised the question about how some folks have to really wrench down the clutch knobs to get the gear to stay put...other don't seem to. It does not make sense to new users of the system... so here goes a quick explanation of the design, what goes wrong, and a simple solution...
The mount was originally designed (G11, GM8) to be a push-to, with its very nicely accurate RA and DEC markings.?? Only later when the astrophotography field really developed, did everyone find these mounts to be superior due to their high stability and low PE. The Gemini system provided complete GoTo, and its easy computer interface makes it a delight to find deep sky targets for imaging.??
But... the clutches... are the same as originally designed for push/slip operation.? The clutches lead to trouble for AP work with heavy mass systems.? ?There are reports all over the web about how these slip.. a subtle bump in the dark and ... much wasted time re-synching or re-aligning while the precious imaging target slides across the sky.? ? ? The 3-handled clutch knobs are a benefit, and extra cost, but the system still slips for high scope weights.??
? Losmandy supplies a plastic disk, which they now say they have a higher friction plastic, but they did not have them in stock for my GM8 or my older CG11.
The biggest problem is not really the friction, it is inevitable oily contamination. ? ? I found was diffusion of oils from the lubricated needle bearings, and the tight surfaces allow that to move into the clutch surface by capillary action.?? ? ? Over time, the clutch disk will get an entire surface coated in oil and that of course can never by held firmly by the clutch mechanism.
The nice website has written that cardboard is a better clutch material... but of course cardboard can get moist...and does not resist oils.
I have found a much better material for this purpose - oil and water proof and higher friction.?? ? ? I use mine on the GM8 and CG11, and have a heavy Meade LX200R 12 inch SCT on the CG11.? It does not budge during imaging.?? ? ? You don't need much clutch knob force to hold the scope system quite firmly.?? ? ? ? ?This saves possibly distorting the flat metal surfaces.?? ? ? The RA and DEC will still budge if strongly pushed, but not with a casual bump in the night.?? ? ? If one sets mount limits, particularly for unattended astrophotography, there is no issue, but even if the system RA were to run into the mount, these clutch disks will slip to prevent serious damage.??
Let me know in an email to mherman346@... if you want a set of these improved clutch disks for astrophotography work.? ? ? ?I have? G11 (2 of 4.25 inch OD), GM8 (2 of 3.0 inch OD), and also for my own CG11 (one each 4.25 and 3.5 inch OD).? Let me know if you need a different OD for Titan etc.? They mail in a flat envelope that should ship at low cost.?
Very best, Michael
On Wed, Oct 11, 2017 at 11:33 AM, tom loeblt@... [Losmandy_users] <Losmandy_users@...> wrote:
?
First, you should shoot for good balance of the load and then introduce
a slight eastward bias. Clutch tight enough so that there is no slippage
during imaging or slewing.
Tom
On 10/11/2017 2:20 PM, Brian Valente bvalente@... [Losmandy_users]
wrote:
>
>
> I should clarify that I use it primarily for astrophotography and use
> computerized go-tos
>
>
> B
>
> On Wed, Oct 11, 2017 at 11:06 AM, Brian Valente <bvalente@...
> bvalente@...>> wrote:
>
> Hand tightened is fine. you don¡¯t have to crank them down. ____
>
> __ __
>
> Also depends on the load. If it¡¯s heavier it¡¯s worth an extra
> confirming twist____
>
> __ __
>
> hth____
>
> __ __
>
> Thanks____
>
> __ __
>
> Brian____
>
> __ __
>
> __ __
>
> Brian Valente____
>
> Brianvalentephotography.com____
>
> __ __
>
> *From:*Losmandy_users@yahoogroups.com
> Losmandy_users@yahoogroups.com>
> [mailto:Losmandy_users@yahoogroups.com
> Losmandy_users@yahoogroups.com>]
> *Sent:* Wednesday, October 11, 2017 11:04 AM
> *To:* Losmandy_users@...
> Losmandy_users@yahoogroups.com>
> *Subject:* [Losmandy_users] Mount Clutch Tensions____
>
> __ __
>
> ____
>
> Tonight I will have this G11 out for the first time. I've had a few
> dry runs in the house just to become familiar with the working parts
> of the mount and Gemini 2 HC.
>
> My question. How tight should the Dec and RA clutches be in GOTO
> mode and tracking? Partially or more tight? Assuming the scope is
> well balanced prior to using the GOTO mode of course.
>
> Thanks____
>
> __ __
>
> ____
>
>
>
>
> --
> Brian
>
>
>
> Brian Valente
> portfolio <>
>
>
>
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Re: Mount Clutch Tensions
I read the balance instructions for this Losmandy scope Mount. I have to balance the RA and the Dec axis's before hand. To ensure a minimal load on the servo motors during the scope movement. I played with this in the room here and saw what too loose of a clutch can do. Scope will flip-flop around. Have to be careful not to damage the scope and hold it with your hand while doing the balancing.
So I sort have a mediocre tension on those. From a 1-10 scale probably a 4 or 5...
Thanks for your input!
Rodney
|
Re: New G11 / Gemini 2 user with issues..
Hey there Chip..
?
Want to disassemble?? Absolutely not..
Too many questions of how tight, how loose, etc.. But I do love the design of
the G11.. Elegant, yet simple, so I am not afraid to.. Especially with Michael
a short drive away..
?
A ¡°Tweak¡± is what I vote
for.. When I first got it, I dropped the Dec Axis onto the RA Motor hard enough
to nick the Dec housing.. Sounded fine when I used it.. And it sounded fine
after the first time I drove saddle into the RA axis.. Even though I was
standing there watching for it, I didn¡¯t hit the stop button soon enough
this time.. Both times, I essentially pressed the Servo Motor toward the worm..
?
Once my grease arrives, and I start
trying to free up the Dec axis, I *assume* I can ¡°untweak¡± it with
some adjustment somewhere..
?
But really, what I need to do is use it,
as I keep learning little tidbits here and there that are all lightbulb
moments.. Gemini 2 doesn¡¯t work anything like the LX200 Classic, though
my latest ¡°AH HA!¡± moment ¨C The Losmandy PAC video ¨C
makes me think that I might have a clue of how it works..
?
One thing I will need to address is the
nose heaviness of the Triplet objective mated to a carbon fiber tube.. My
Dovetail is too far back in the saddle.. I have room to adjust that quite bit,
if I use a different mounting routine.. i.e. mount the plate / rings, then drop
the OTA into the rings.. That¡¯ll be this weekend..
?
Definitely learn something new every
time out.. I am hopeful that it¡¯ll all come together next time I try it..
?
Derek
?
From:
Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Wednesday, October 11, 2017
1:28 PM
To: Losmandy_users@...
Subject: [Losmandy_users] Re: New
G11 / Gemini 2 user with issues..
?
?
Hi Derek,
Hmm, it sounds like you may have damaged a gearbox. The older gearboxes
used soft plastic studs that were heated and pressed to form a bad rivet which
retained the plate which supported these tiny metal pins which the plastic
internal gears would spin on. If you had a gearbox/motor strike with the
clutches locked up you may have dislodged or tweaked a gearbox just enough to
make noise but not have obvious external damage without removing the servomotor
and gearbox. you will want to remove the metal cover, then remove the motor and
gearbox to inspect the gearbox that was hit. If I were up there I would help
you and Michael is traveling so you are sort of on your own, but we can help
you virtually if needed. You really wanted to disassemble your new mount anyway
didn't you??
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Re: Super greasy worm gears on my GM8
Fredrik,
Is this a #492 digital drive GM8? I bought a demo GM8 with #492 digital drive looking for a lighter payload mount than my G11 for driveway duty on a JMI Wheely Bar and lighter payloads for visual work in the field. The GM8 is possibly the sweetest mount ever made when used in PUSH-TO mode as it was designed to be used. The Porter slip clutch design is an elegant very smooth working solution for this old school use. I have since added a Gemini to my GM8 but it still works the same way and for visual use remains a wonderful mount. The Gemini just adds to the enjoyment when looking for those low mag objects.?
Clean it up and get as much of the grease off of the exterior to help reduce the capture of dust and dirt. If it gets captured on the outside, sooner rather than later, the dirt will get inside and forcing you to degrease and relube the drivetrain. Keeping the amount of lubricant used to a minimum helps keep the dirt out.?
Chip
|
Re: New G11 / Gemini 2 user with issues..
Hi Derek,
Hmm, it sounds like you may have damaged a gearbox. The older gearboxes used soft plastic studs that were heated and pressed to form a bad rivet which retained the plate which supported these tiny metal pins which the plastic internal gears would spin on. If you had a gearbox/motor strike with the clutches locked up you may have dislodged or tweaked a gearbox just enough to make noise but not have obvious external damage without removing the servomotor and gearbox. you will want to remove the metal cover, then remove the motor and gearbox to inspect the gearbox that was hit. If I were up there I would help you and Michael is traveling so you are sort of on your own, but we can help you virtually if needed. You really wanted to disassemble your new mount anyway didn't you??
Cheers/Chip
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Re: Mount Clutch Tensions
Hi Rodney,
Ideally you want to snug the clutch knobs up just enough to hold and no more but it really makes about zero difference to the servomotors. Obviously there will be a very small additional load placed on the thrust bearings if you really crank the knobs down but in reality this presents minimal additional load on the servomotors because for the most part the thrust bearings are already fully loaded by gravity working on the load presented by the mount and any payload in the saddle. You can easily verify this if you have a Gemini 2 by monitoring the lag data on the Servo page of the Gemini. You can have the clutch fully loose and fully tight and will see no change in lag or duty cycle.?
Chip
|
Re: Mount Clutch Tensions
First, you should shoot for good balance of the load and then introduce a slight eastward bias. Clutch tight enough so that there is no slippage during imaging or slewing.
Tom
toggle quoted message
Show quoted text
On 10/11/2017 2:20 PM, Brian Valente bvalente@... [Losmandy_users] wrote: I should clarify that I use it primarily for astrophotography and use computerized go-tos
B
On Wed, Oct 11, 2017 at 11:06 AM, Brian Valente <bvalente@... <mailto:bvalente@...>> wrote:
Hand tightened is fine. you don¡¯t have to crank them down. ____
__ __
Also depends on the load. If it¡¯s heavier it¡¯s worth an extra
confirming twist____
__ __
hth____
__ __
Thanks____
__ __
Brian____
__ __
__ __
Brian Valente____
Brianvalentephotography.com____
__ __
*From:*Losmandy_users@...
<mailto:Losmandy_users@...>
[mailto:Losmandy_users@...
<mailto:Losmandy_users@...>]
*Sent:* Wednesday, October 11, 2017 11:04 AM
*To:* Losmandy_users@...
<mailto:Losmandy_users@...>
*Subject:* [Losmandy_users] Mount Clutch Tensions____
__ __
____
Tonight I will have this G11 out for the first time. I've had a few
dry runs in the house just to become familiar with the working parts
of the mount and Gemini 2 HC.
My question. How tight should the Dec and RA clutches be in GOTO
mode and tracking? Partially or more tight? Assuming the scope is
well balanced prior to using the GOTO mode of course.
Thanks____
__ __
____
--
Brian
Brian Valente
portfolio brianvalentephotography.com <>
|
Re: Mount Clutch Tensions
Never tighten more than the minimum required to prevent slippage. Doing so dramatically increases drag due to (unnecessary) loading of the thrust bearings.
Good Luck !
Jeff
|
Re: Mount Clutch Tensions
That is my goal as well Brian, but I was just wondering how tight these clutches should be for all of the different modes, GOTO, tracking, etc...
I had them really tight when i was learning this mount, but I realize too if they are too loose the scope will drop...
Rodney
|
Re: Mount Clutch Tensions
I should clarify that I use it primarily for astrophotography and use computerized go-tos
B
On Wed, Oct 11, 2017 at 11:06 AM, Brian Valente <bvalente@...> wrote: Hand tightened is fine. you don¡¯t have to crank them down. ? Also depends on the load. If it¡¯s heavier it¡¯s worth an extra confirming twist ? hth ? Thanks ? Brian ? ? Brian Valente Brianvalentephotography.com ? ? ? Tonight I will have this G11 out for the first time. I've had a few dry runs in the house just to become familiar with the working parts of the mount and Gemini 2 HC.
My question. How tight should the Dec and RA clutches be in GOTO mode and tracking? Partially or more tight? Assuming the scope is well balanced prior to using the GOTO mode of course.
Thanks ?
-- Brian?
Brian Valente portfolio
|
Re: Mount Clutch Tensions
I just have a push-to GM-8, and a lot of times I'll reach down to loosen the clutch to go to another object and find them already "loose". I don't have to tighten mine much at all with C8's or an AT130. Some people have to really wrench them down. I don't know what the difference is. I suppose if you were going to leave the telescope alone you would want to tighten them down a good bit in case the wind came up.
Bob
|
Re: Mount Clutch Tensions
Hand tightened is fine. you don¡¯t have to crank them down. ? Also depends on the load. If it¡¯s heavier it¡¯s worth an extra confirming twist ? hth ? Thanks ? Brian ? ? Brian Valente Brianvalentephotography.com ?
toggle quoted message
Show quoted text
From: Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Wednesday, October 11, 2017 11:04 AM
To: Losmandy_users@...
Subject: [Losmandy_users] Mount Clutch Tensions? ? Tonight I will have this G11 out for the first time. I've had a few dry runs in the house just to become familiar with the working parts of the mount and Gemini 2 HC.
My question. How tight should the Dec and RA clutches be in GOTO mode and tracking? Partially or more tight? Assuming the scope is well balanced prior to using the GOTO mode of course.
Thanks ?
|
Tonight I will have this G11 out for the first time. I've had a few dry runs in the house just to become familiar with the working parts of the mount and Gemini 2 HC. My question. How tight should the Dec and RA clutches be in GOTO mode and tracking? Partially or more tight? Assuming the scope is well balanced prior to using the GOTO mode of course. Thanks
|
Re: Super greasy worm gears on my GM8
Heh, that's good to hear! I was hesitant to buy it at first since it was still just outside my budget for a mount that's 20 or so years old. I realized that most of the mount will stay the same through the years since the build quality is so darn good. I imagine I'll have to change the motors and gears eventually but hopefully that won't be needed this year.
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photon_trap
Eric Chesak
Michael Herman