Re: 1st time buyer: Recommended knobs other than CKS?
? ? ?Hello Sean,?
Welcome to the Group,?
For what it is worth, when I travel with my mount I still bring with me extra suff with me. Such as a spare set of DEC and RA cables,? nothing like forgetting to pack these to put a pall on the night. Along with a extra power suppy and general stuff like this that I may need. I assemble and disassemble for each viewing session and I really like the TKS knobs? they make this process a snap.
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? ? ? You will love your new mount. Especially after you really get to understand it. I had a few issues with my G11G at first and everyone here on this Group came to my rescue,? especially Brian Velente,?
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HAPPY SKIES TO YOU AND KEEP LOOKING UP Jethro
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-------- Original message --------
From: Michael Ben-Yehuda <mikeby.mikeby@...>
Date: 7/26/21 9:26 PM (GMT-06:00)
Subject: Re: [Losmandy_users_io] 1st time buyer: Recommended knobs other than CKS?
?
Hi Sean,
Welcome to the group. I am new to Losmandy as well. I just bought a used G11 mount and am reading and learning a LOT from this group.
There are a lot of very experienced people here. A real wealth of knowledge and lots of help and support.?
+1 what others have said
TKS? if you are going to be?setting up and taking down the mount each night.?
AKS if you intend to travel to multiple locations to do your observing.?
Sort out the power supply and power cables you'll need.
Totally agree with eliminating the need for small tools and wrenches wherever possible.
I might suggest you add to the list a couple small strap wrench.(Photographers may call them 'filter wrenches'). or flat rubber bungee for that purpose.
With machined tolerances tighter than what's typically seen it's possible that threaded parts can get 'stuck' from the small bits of debris especially if they get over tightened.? My mount is more than 10 years old and the fastener fit is still noticeably closer then other gear I have.?
Nice thing about a mount that is all machined is that you don't need to crank down?on the fasteners to have things stay put. In general, snug tight is just right.? I don't know what other
mounts you may have worked with, but for me it's so nice to no longer feel non-true castings flex as you torque a hex bolt realizing that whatever was set is now off. It's still advised to work with things 'snug' and then slowly tighten when doing alignment, but what a difference.
For me anyway it's really a pleasure even when dealing with a used mount and needing to fix up bits of accumulated maintenance and previous wrongdoings. It keeps me busy while waiting for a night that's not cloudy or foggy LOL.
Clear skies,
Michael
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Re: New subscription to Losmandy user group
Welcome Frank,
A? wealth of knowledge and very experienced users here.? I've found it very helpful.
Just bought a used G11 recently which is my 1st Losmandy mount which I'm still tuning up and getting parts
together for.? The usual cloudy nights anytime something new arrives, so it's all working out.? ?:)
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Re: 1st time buyer: Recommended knobs other than CKS?
Hi Sean,
Welcome to the group. I am new to Losmandy as well. I just bought a used G11 mount and am reading and learning a LOT from this group.
There are a lot of very experienced people here. A real wealth of knowledge and lots of help and support.?
+1 what others have said
TKS? if you are going to be?setting up and taking down the mount each night.?
AKS if you intend to travel to multiple locations to do your observing.?
Sort out the power supply and power cables you'll need.
Totally agree with eliminating the need for small tools and wrenches wherever possible.
I might suggest you add to the list a couple small strap wrench.(Photographers may call them 'filter wrenches'). or flat rubber bungee for that purpose.
With machined tolerances tighter than what's typically seen it's possible that threaded parts can get 'stuck' from the small bits of debris especially if they get over tightened.? My mount is more than 10 years old and the fastener fit is still noticeably closer then other gear I have.?
Nice thing about a mount that is all machined is that you don't need to crank down?on the fasteners to have things stay put. In general, snug tight is just right.? I don't know what other
mounts you may have worked with, but for me it's so nice to no longer feel non-true castings flex as you torque a hex bolt realizing that whatever was set is now off. It's still advised to work with things 'snug' and then slowly tighten when doing alignment, but what a difference.
For me anyway it's really a pleasure even when dealing with a used mount and needing to fix up bits of accumulated maintenance and previous wrongdoings. It keeps me busy while waiting for a night that's not cloudy or foggy LOL.
Clear skies,
Michael
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Re: New subscription to Losmandy user group
Welcome to the group Frank!
This is a great group to find information and assistance when needed.? Feel free to ask questions when you get stumped.? Everyone here is helpful, knowledgeable, and persistent in finding solutions.
- Jerry?
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Re: GM8 Counterweight Bar Won't Thread In
Ken,
You might want to try looking at the males and female threads using a magnifying lens, and use a flashlight to look inside. See if there are any burrs getting in the way. Sounds like it was a tight fit from the start, and you plowed up the high spots. You probably won't get the right insertion until the obstacles are out of the way. Other than what's been recommended already, you may want to contact Losmandy support since you are under warrantee.?
Good luck!
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Re: New subscription to Losmandy user group
Hi Frank,
Congrats on your mount purchase! You'll find lots of info searching through this forum and also on the Losmandy YouTube channel. Good luck with your setup!
John
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New subscription to Losmandy user group
Hello, I have just completed the sign up for the group. I am now sending my ¡°sign-up¡± message. I have joined the Losmandy user group, because I am eagerly awaiting the delivery of a new GM8, hopefully within the next couple of weeks! ? Best Regards, Frank Cornish ? 206 Rushmore way Canton Georgia ?
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Re: GM8 Counterweight Bar Won't Thread In
On Mon, Jul 26, 2021 at 12:34 PM, Michael Herman wrote:
If truly only 2 months old, contact the factory and ask for a replacement counterweight rod with threads slightly reduced in OD.? Stop putting time into this...it was not made right.? The correctly made shafts and bore holes go into each other with hand tightening.??
IF it worked originally the first two months, there's nothing wrong with the thread size.
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Re: polar scope binding - RA thrust bearing thickness stiction and more.
Michael,
See the nice notes and photos on Mark Crossley's website:
Look for his section on tips and tricks.
He also lists the standard parts for the G11.? And his recommended clutch knob assembly order.? And adding a spring wire to the polar scope flange.
Please consider buying a Polemaster as an option to make polar alignment much easier than with the polar scope. Save your back and neck and knees.
Best, Michael
Hello,?
I just bought a G11 and am working through it's issues. I know every mount has it's quirks, but some of these I didn't expect.
RA axis the polar scope locking collar was very loose. So I snug it up and make sure I can still rotate the scope but that there's no play.?
Then I tighten the RA clutch and discover that the polar scope can no longer be turned. It's pushing hard against it's locking collar. I had noticed that the scope
turned with the locking collar, which I did not expect. but this was something else.? Relaxing the clutch the polar scope frees up.? I remove the polar scope and tighten the clutch
again. This time i look at the polar scope and eventually discover that the silver focus lock collar is hitting against the RA axis shaft. The only solution is that there must be a spacer missing.?
I go ahead and pull apart the RA drive check the internal bearings and clean the clutch plate and surfaces to get rid of slippage. I discover that the two thrust washers are of different thickness. One is 0.10" and the other is 0.03" . I have no idea if this is correct.? ?The seller had given me a small box with some parts.? In there I find 2 thrust bearings and 2 thrust bearing roller assemblies. The thrust bearings measure 0.125". thick.
Can someone tell me what the thrust bearing thickness is supposed to be?? If I change the .030" bearing for the .125" bearing there may be just enough space for the polar scope to seat correctly.?
Thanks in advance..
Michael.
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Re: GM8 Counterweight Bar Won't Thread In
Kenneth,
If truly only 2 months old, contact the factory and ask for a replacement counterweight rod with threads slightly reduced in OD.? Stop putting time into this...it was not made right.? The correctly made shafts and bore holes go into each other with hand tightening.??
Best, Michael
Thanks for all the thoughtful replies.
I did clean out the female threads with some nitro-solvent (gun bore cleaner), then lubed with a light coating of gun oil.?
No change as yet. I see from the comments I want to more closely inspect the threads, and try some additional cleanings, and perhaps some of the other steps mentioned.?
Thankfully it is still functional, goes deep enough that it is in safely/solidly.? I'm going to take my time trying a few of your suggestions first. Since I got the mount less than 2 months ago, I'm still too excited to use it/learn it to consider sending it in for service!
Thanks to all,? I can see this is a great community and I look forward to participating in it!
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Re: GM8 Counterweight Bar Won't Thread In
Thanks for all the thoughtful replies.
I did clean out the female threads with some nitro-solvent (gun bore cleaner), then lubed with a light coating of gun oil.?
No change as yet. I see from the comments I want to more closely inspect the threads, and try some additional cleanings, and perhaps some of the other steps mentioned.?
Thankfully it is still functional, goes deep enough that it is in safely/solidly.? I'm going to take my time trying a few of your suggestions first. Since I got the mount less than 2 months ago, I'm still too excited to use it/learn it to consider sending it in for service!
Thanks to all,? I can see this is a great community and I look forward to participating in it!
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Re: At some point, I may begin commenting on the G11 DEC axis...
On Mon, Jul 26, 2021 at 05:49 AM, alan137 wrote:
Then again, I am using a BIG 12" F4 tube newtonian.?
Allan, I'm excited to see that you can carry the bad boy!.??I think I might mount mine to the coming weeks.? Do you have plans to upgrade the optical encoder to 1024. I think you will see a very noticeable benefit. It's a $65 investment and you do not have to remove anything from the drive other than the motor end plate can do everything insitu.? It would be nice to have a second reference point to go by. With a minimum step size of 0.56 arc-sec and I would imagine longer settling times due to the weight, having the ability to make smaller 0.14 arc-sec steps would be beneficial. I've ended up with a min step size of 0.05 in PHD2, compared to 0.4 before I made the alteration. With good polar alignment I would expect on only having to make little tweaks.? Here is my guide graph from last night showing just how small the corrections are and lack of reactionary overshoots. The scale is +/- 1s if the scale is not readable ? I found it useful to remove the motor and use my fingers to judge the worm mesh to get both side touching. It's such a fine adjustment thing. Also, I would highly recommend changing out the thrust bearing. It made a large difference for me. Peter
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Re: On why the clutch knob matters to worm mesh to the ring gear...
And a lingering mystery...has another clue (I have been reading Perry Mason mysteries....it's true):
Though I explained that the ring gear sits stop the flat upper thrust needle bearing, this fact alone does not explain why the worm to ring gear gap is (on some systems!) affected by the clutch knob tightness.? I said you might see this if the OTA were sideways or upside down, but people are seeing this even at CWD.? Why?? That's a remaining mystery.??
And why did replacing the same flat thrust needle bearing with a new one make the ring to worm spacing better (as it did for Peter and for me)?? We thought the new needle bearing had a different thickness than the old bearing.? But I had not measured it to see.??
Now I have...and the answer is:
I just measured the thickness of the rollers of the old and another new flat thrust bearing? ?Surprise! The thicknesses are identical.? Both measured 0.0775 inch with my digital vernier caliper.? So the replacement thrust bearing did not change the vertical distance between the worm and ring gear!??
What the heck?? Call Sherlock Holmes!
But there is another clue: ?the old thrust bearing frame is warped!? Not flat!? So if the steel thrust bearing frame becomes warped, that can act like a spring!? That is what could be pushing the ring gear higher, above the thrust bearing, and jamming the worm.? And when you tighten the clutch knob, the thrust bearing frame flattens and makes the worm to ring gear correct and not jammed.
Here are photos of the old and new thrust bearings.? The new one has a metal retainer in the center of the rollers. There is also a photo of just the new thrust bearing by itself.? ?
So: if you are experiencing this unusual phenomenon on your system: The worm to ring gear adjustment is affected by the clutch knob force, at the CWD position, I'd suspect you need a new upper thrust bearing (~$15 from McMaster-Carr).??
This also explains why Losmandy puts a wavy or Belleville spring washer under the clutch knob end of the axis.? That spring is intended to always put a force on the clutch pad, the ring gear, and the upper thrust bearings, and keep the ring gear at the right height for the worm gear.? The problem is friction between the worm and ring gear at the point if contact...very high force and therefore enormous pressure is there.? So friction there can push up or down the edge of the ring gear.? That's why you need a very low friction grease that is intended for such high pressure ...(again I suggest the CRC Brake and Caliper Grease for that gear interface).??
All the best, Michael
Thanks for the write up.? I did not know the ring gear sits on only a needle thrust bearing, and effectively a bushing sleeve.? I would have thought it used a bearing for radial constraint, but ok, whatever.
As long as it can spin with low friction.
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Re: At some point, I may begin commenting on the G11 DEC axis...
oh right, another thing is that it STILL takes about 15 seconds after a dither move for the axis to "settle down".? ? Whereby "settle down", I mean that guiding is reliable again without any sudden unexpected moves.? Maybe NINA or PHD makes the dither move too suddenly?? I know from adjusting the focus knob that it only takes about 3-4 seconds for the scope to stop vibrating.
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Re: At some point, I may begin commenting on the G11 DEC axis...
Hello again,?
I thought that maybe there would be a lot to say, but there isn't.? The G11 DEC axis seems to work well over a fairly wide range of worm meshes.? Maybe because it has low friction even with a medium-tight clutch, and so it can rotate with minimal stiction, hysteresis, etc.? If the mesh is too tight, the backlash test will show an initial rise (just like I showed with the G8 axis), and the guiding will show characteristics of "forwards lash", where PHD will try to push the mount north, but instead it will move south even further before suddenly snapping back.
On the other hand, I made the mesh looser and looser until it was obviously rattling, and the PHD test and guiding were still good.? I think this is because my scope setup is "right side heavy", and so it always wants to rotate the DEC axis clockwise when viewed from above.? In this instance, only one side of the worm teeth are loaded, and you are pretty much running it like an "east heavy" RA axis.? Probably this method reduces worm to ring friction.
I did these tests with TVC = 10 and at large deflections there is almost no hysteresis, so maybe this value is at risk of being a little too high.? Usually these backlash values (as called out via a single number via guiding assistant) range from about 400-800ms, and turning off TVC adds another 7-800 ms.? It's a shame that PHD backlash test won't use smaller than 500ms steps, otherwise we could see better what happens at the initial turn-around point.? I think the ideal worm mesh will be what makes the backlash plot turn around as soon as possible, even if there is some backlash gap at larger displacements.
The only remaining problem is that even the lightest puff of wind will cause the axis to go off by 1-2 arc-sec.? Then again, I am using a BIG 12" F4 tube newtonian.? Perhaps if I increased the weight imbalance for more DEC preloading, that would make it "stiffer"?? I've also been slowly tightening the worm mesh to hopefully find the point where both sides of the worm teeth just start to engage.? Perhaps this is the "correct" worm mesh, and would require an infinitesimally light pressure if the worm were truly "spring-loaded".
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Re: Need advice selling my Losmandy G11 492 Digital Drive
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-------- Original message --------
From: George Cushing <stm32bluepill@...>
Date: 7/25/21 4:10 PM (GMT-05:00)
To: [email protected]
Subject: Re: [Losmandy_users_io] Need advice selling my Losmandy G11 492 Digital Drive
Paypal has just futzed around with the fee structure, so it's best to look at the user's agreement. I scanned it and there are a lot of additional things that will generate fees.?
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Re: On why the clutch knob matters to worm mesh to the ring gear...
Thanks for the write up.? I did not know the ring gear sits on only a needle thrust bearing, and effectively a bushing sleeve.? I would have thought it used a bearing for radial constraint, but ok, whatever.
As long as it can spin with low friction.
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Re: New G11G with subpar guiding
I'll definitely look into PEMPro, Brian also mentioned the Oldham coupler misalignment so that's already someting I'm looking to fix. Hopefully that will get this to be good enough but if not, the Belleville washer upgrade doesn't seem too dificult from what I've read about it.?
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Re: GM8 Counterweight Bar Won't Thread In
The thread is probably 1" x 16tpi.? You can confirm by holding one of Losmandy's 3/8" x 16 tpi bolts up to it to check.
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Re: Need advice selling my Losmandy G11 492 Digital Drive
Paypal has just futzed around with the fee structure, so it's best to look at the user's agreement. I scanned it and there are a lot of additional things that will generate fees.?
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Michael Herman