Re: G11 Drive Gear Removal
Thanks Michael. I do have the tucked motors and the two bolt plate. The gears you are showing appear to be steel, perhaps with hardened teeth; mine are aluminum. I would think steel would be better for flexure, and resistance to damage and wear.
Just took another look at the screws. Even while magnified, it is hard to make out a hex shape (attached). Perhaps they were rounded off when inserted and that is why no wrench is working. Not sure how then to remove the gear. Perhaps pull off the shaft with force, or drill out somehow. But with the latter I am not sure if if I have a drill and tap that small. I will dig through the info you sent, perhaps there are replacement gears of the same size available.
Best Regards,
John
|
Re: Typical Guided Performance of GM8G, GM811G, and G11
Hi Liam,
I just want to point out that for AP there are telescopes that work, and telescopes intended for visual observing only, they don't work so great with cameras.
The best explanation I know of comes from Forrest Tanaka. Watch how he describes the differences. Particularly for Newtonian telescopes, and the placement of the reflector mirror. He modified his own Newt.
https://youtu.be/9d0292TBMHo?t=95
--
SonnyE
(I suggest viewed in full screen)
|
Re: G11 Drive Gear Removal
Thanks Jim. At least you got the screw loose. Sounds like a gear puller needs to be employed.
|
Re: G11T vs AstroPhysics - opinions wanted
I
believe you said ¡°EAA¡±.. i.e. you¡¯ll be looking at the computer
screen?? If that¡¯s wrong, then ignore this message..
?
If
that¡¯s the case, then you don¡¯t need anything remotely close to a
Paramount or a 10 Micron, you just need a G8 or G11 etc that can hold the
optics.. It¡¯s all about image scale.. My small chip camera has an image
three times bigger than my computer screen and displaying the entire image
squishes (scientific term) it down.. I get fantastic views from my cameras of
30s unguided.. Simple guiding for an onscreen view would be easy.. You would
only need the perfection of high end and expensive equipment if you wanted to
image for long periods and process them to perfection..
?
Point
being, I thought this was for EAA imaging and that was forgotten along the
way.. For EAA ¨C and even for perfection ¨C Losmandy mounts are most
certainly the best ¡°bang for the buck¡±..
?
If
this has nothing to do with EAA, then forget I said anything other than my G11
is fantastic and I am very glad I was convinced to get one..
?
Derek
?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of altuttle@...
Sent: Friday, February 26, 2021
1:15 PM
To: [email protected]
Subject: Re: [Losmandy_users_io]
G11T vs AstroPhysics - opinions wanted
?
Thanks a ton for these latest replies!!!
Yes, I do know the added costs.... (my spreadsheet is a scary thing to look
at).? ?It's the same story with all the next tier mfgrs I've looked
at (AP, Paramount,
10micron, & Planewave), in some cases even having to rebuild/modify the
observatory.? I can convince myself (& the CFO) that the cost is
justified.....? but I have doubts that I really need to go that far.
Chip, your comment really hits home.? I'm looking for a relatively high
capacity, strong mount that tracks very smooth.? I have several scopes
(mostly mid-tier) and I change them often to suit the season/targets.? As
such balance and position often changes a bit, so parking position for easy
restart and pointing models are mostly irrelevant for me.? The level of
controller I have with the Gemini 1 (or even with my Celestron) is more than
adequate.? My problem is drivetrain errors that impact good guiding,
mainly backlash and PE (not the averaged PEC, but the higher frequency
errors/roughness).? ?I don't know if its really necessary to spend 2
or 3 times the price to get those improvements in the gear train, or would much
of that cost be for things like optical encoders and fancier controllers?
I'll think seriously about getting a G11G as a tryout so to speak before going
all-in on a Mach2, particularly if the wait for it gets pushed out
further.? The G11G may be just the ticket.
Thanks again,
al
|
Re: G11T vs AstroPhysics - opinions wanted
Thanks a ton for these latest replies!!!
Yes, I do know the added costs.... (my spreadsheet is a scary thing to look at).? ?It's the same story with all the next tier mfgrs I've looked at (AP, Paramount, 10micron, & Planewave), in some cases even having to rebuild/modify the observatory.? I can convince myself (& the CFO) that the cost is justified.....? but I have doubts that I really need to go that far.
Chip, your comment really hits home.? I'm looking for a relatively high capacity, strong mount that tracks very smooth.? I have several scopes (mostly mid-tier) and I change them often to suit the season/targets.? As such balance and position often changes a bit, so parking position for easy restart and pointing models are mostly irrelevant for me.? The level of controller I have with the Gemini 1 (or even with my Celestron) is more than adequate.? My problem is drivetrain errors that impact good guiding, mainly backlash and PE (not the averaged PEC, but the higher frequency errors/roughness).? ?I don't know if its really necessary to spend 2 or 3 times the price to get those improvements in the gear train, or would much of that cost be for things like optical encoders and fancier controllers?
I'll think seriously about getting a G11G as a tryout so to speak before going all-in on a Mach2, particularly if the wait for it gets pushed out further.? The G11G may be just the ticket.
Thanks again,
al
|
Re: Typical Guided Performance of GM8G, GM811G, and G11
Liam,
The G11 is, in my opinion, the best bang for the buck. It has a greater weight capacity and doesn't cost that much more. Not hard to set up either unless you have serious back problems. This 70+ year old handles it easily.
Unless you go bigger than, say, a 10 inch Newtonian, the G11 will serve you well for years.
Of course, just one persons opinion.
And, of course, for guiding is necessary. Just don't get too greedy on the focal length to start with - guiding is more critical and exposures become long with high f/-ratios.
Mark Christensen
|
Re: G11T vs AstroPhysics - opinions wanted
That is unquestionably true. AP prices are for mount only. You will need counterweights, a counterweight bar, a dovetail to mount your telescope, a flat surface adapter and knobs to mount them on something like a Losmandy tripod all of which add to the price of the mount. Mine came with the counterweights and bar, but I had to purchase the other stuff, along with the V2 chip for the upgrade from the old Q firmware. All that adds up. And I still kept by GM811G because it is a really nice mount and more portable than the Mach 1. Plus the LHD tripod works with both mounts, so that's a win!
|
Re: G11 Drive Gear Removal
There are bolts (I think 2 on the G11 tucked motor system) that hold the vertical plate; that plate holds the gears and gearbox.? ? If you remove the bolts that hold the plate on, then you can take the gear system and gearbox and motor assembly all to your workbench and inspect what's going on.? You will see the Oldham coupler lies beneath the inner transfer gear hub.? So the inner gear rotates the hub that turns the Oldham coupler, and that turns the worm.??
On the bigger G11T RA (Titan drive RA) system there are 3 or 4 bolts that hold the gear plate to the large stainless steel RA worm enclosure end.? The G11T has on its DEC system the same G11 type drive as on the DEC and RA of the G11.??
Here are some photos of my G11T DEC section under inspection.? This has a tucked, not spring loaded, gear train.?
I've been reading on the Sterling Instruments Standard Products website about gears with straight cut teeth.? They recommend some backlash...but not too much backlash.? That's the trick!
Here is a web page with lots of info on gears.? It talks of lubricants, gear tooth edges, worm position etc.??
Have fun, Michael
John
FYI -? I tried removing the upper gear that drives the worm and I couldn't even when I loosened the grub screw.??
Jim
|
Re: G11 Drive Gear Removal
John
FYI -? I tried removing the upper gear that drives the worm and I couldn't even when I loosened the grub screw.??
Jim
|
Re: G11 Drive Gear Removal
Thanks Michael! I tried wrenches from 3 different sets, but none would match. I was thinking of looking for a small precision set somewhere but no luck yet.? But any further info would be great!
Thanks much.
John
|
Re: G11 Drive Gear Removal
Hi John,
The size is nominally 0.050 (I once called the factory and Mr Losmandy told me that is the right nominal size).
I then I also had the same problem on the gearbox gear of the G11T.? I could not get any of my usual hex wrench set (Bondhus brand) either metric or US, to work on that smallest setscrew.? ??
I then tried a different set.? That 0.050 from a different hex wrench set did fit snugly and did work.? That setscew was really tight initially.??
So I think that 0.050 is the nominally correct size, but different hex wrench suppliers get it right.... other don't, or the setscrew itself doesn't have a tight quality. My experience was that small wrench can be off in size, and the setscrew is in really tight.
I can't say (til Sunday night when I get home) which brand hex wrench worked for me, or even that brand's other production would work right.? Maybe these all vary in quality.??
As an alternative approach, you might instead take one other slightly too large hex wrench and slowly shave it down with a file until it fits snugly enough to get that setscrew loose.??
Very best of luck, Michael?
?
Hello all:
Speaking of gearboxes, I am now thinking of the value of potentially replacing one I have on my G11G in hopes of gaining some extra smoothing of RA periodic error. The last time I had my mount apart I saw that to remove these, the external drive gear must be removed from the upper axle of the gear box. Please see attached pic. This is the lower of the two gears shown.
But to remove these, there is a very tiny set screw holding the gear in place on the shafts (backside of gear surface shown). Trying all my small Allen wrenches, 1/16 in. is too big and 1/20 in. is too small. 1.5 or 1 mm don't seem to be right either. If anyone knows the precise wrench size please get back, I don't want to strip or damage the screw. I see there is also a flat spot of the shaft to seat the screw to prevent any slippage, but holding them tight. Then after the loosening the screw, will I need a gear puller or will they just slide off? I'm sure there are a few out there who have completed this procedure.
Just to note, I see that when operating at sidereal speed, both these gears rotate with the same period as the worm, or slightly less than 240 seconds. Just wondering if these gears could also contribute to periodic error somehow as well, like if they are not perfectly round, have tooth wear or damage, or are not perfectly concentric on the shafts. Such imperfections could slow or speed up worm rotation, but perhaps not as much as the worm to ring gear fit. Tension between these gears is of critical adjustment as seen in the Losmandy video on how to set the worm blocks. Just thinking out loud on this part.
But Allen wrench size and need of a gear puller are what I need to know the most. Many thanks if anyone could forward the information.
Best Regards,
John
|
Re: Weird tapping noise from RA gearbox or motor. Please, watch a movie.
Hi!
I've had similar knocking sounds at times. I had it last night, adjusting the RA gear. It disappeared last night when I adjusted the worm against the big wheel - I have a OPW and screwed it out 1/4 of a turn - knocking sound disappeared. Seems it was to do with the worm being to tight against the wheel, in certain spots - but seemingly not tight enough to produce a stall.?
Magnus
|
Re: Typical Guided Performance of GM8G, GM811G, and G11
I
just finally got a decent DSO image, so count me in the ¡°if I can do it,
anyone can do it¡± category..
?
Tonight
was below the normal.. 3 hours and I was at 0.92 arcseconds total RMS on both
axis.. Normal
is ~0.75, but my seeing was bad.. Polar Alignment is off by 5 arcmins..
?
Old
style G11 with Gemini 2 bought used 3 years ago.. 130mm Triplet guided by an
80mm doublet, both at f/7..
?
Derek
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Liam C
Sent: Thursday, February 25, 2021
9:50 PM
To: [email protected]
Subject: Re: [Losmandy_users_io]
Typical Guided Performance of GM8G, GM811G, and G11
?
Thanks
all, I really appreciate the thoughtful responses. It sounds like the GM8G with
a guide scope should be a pretty decent setup to start with. Since my focus is
on live stacking at outreach events, I will probably mostly use it for the
larger and brighter objects. I currently have a 750mm FL 6-inch Newtonian on a
stock mount and a 200mm FL DSLR lens for wide field. Eventually I may look into
getting an APO refractor somewhere in between
those focal lengths.
|
Hello all:
Speaking of gearboxes, I am now thinking of the value of potentially replacing one I have on my G11G in hopes of gaining some extra smoothing of RA periodic error. The last time I had my mount apart I saw that to remove these, the external drive gear must be removed from the upper axle of the gear box. Please see attached pic. This is the lower of the two gears shown.
But to remove these, there is a very tiny set screw holding the gear in place on the shafts (backside of gear surface shown). Trying all my small Allen wrenches, 1/16 in. is too big and 1/20 in. is too small. 1.5 or 1 mm don't seem to be right either. If anyone knows the precise wrench size please get back, I don't want to strip or damage the screw. I see there is also a flat spot of the shaft to seat the screw to prevent any slippage, but holding them tight. Then after the loosening the screw, will I need a gear puller or will they just slide off? I'm sure there are a few out there who have completed this procedure.
Just to note, I see that when operating at sidereal speed, both these gears rotate with the same period as the worm, or slightly less than 240 seconds. Just wondering if these gears could also contribute to periodic error somehow as well, like if they are not perfectly round, have tooth wear or damage, or are not perfectly concentric on the shafts. Such imperfections could slow or speed up worm rotation, but perhaps not as much as the worm to ring gear fit. Tension between these gears is of critical adjustment as seen in the Losmandy video on how to set the worm blocks. Just thinking out loud on this part.
But Allen wrench size and need of a gear puller are what I need to know the most. Many thanks if anyone could forward the information.
Best Regards,
John
|
Re: Typical Guided Performance of GM8G, GM811G, and G11
Thanks all, I really appreciate the thoughtful responses. It sounds like the GM8G with a guide scope should be a pretty decent setup to start with. Since my focus is on live stacking at outreach events, I will probably mostly use it for the larger and brighter objects. I currently have a 750mm FL 6-inch Newtonian on a stock mount and a 200mm FL DSLR lens for wide field. Eventually I may look into getting an APO refractor somewhere in between those focal lengths.
|
Re: I put a G11 gearbox in the freezer...
On 2/25/2021 6:49 PM, davidfenster@... via groups.io wrote: Hey Brian - Ain't ragging on the mount.? I love mine.? I have always used slow slew speeds as I think everything is happier that way.? I also use a higher voltage power supply.
All I'm sayin' is try it.? Throw a gearbox in the freezer and then report back (Pretty sure you all have a few lying around).
All the best,
Dave Just FWIW, I have a newer GM811 running on 12V on the same 5A supply that runs my mini-PC and cameras and have zero issues here in metro Detroit at temperatures as low as 10F. I do not limit the slew rate. The motors sound exactly like they did last fall when it first arrived and it was warm outside. Paul -- Paul Goelz Rochester Hills, MI USA pgoelz@... www.pgoelz.com
|
Re: I put a G11 gearbox in the freezer...
I'm guessing alcohol.? any solvent that won't eat the plastic case/gear.? There is a plastic gear so be aware of that (no idea what won't eat that)
|
Re: I put a G11 gearbox in the freezer...
>>>Throw a gearbox in the freezer and then report back (Pretty sure you all have a few lying around).
that's the first thing I did when i read your post :)?
then I emailed scott :) :)?
then i checked the support logs :)?
Hey Brian - Ain't ragging on the mount.? I love mine.? I have always used slow slew speeds as I think everything is happier that way.? I also use a higher voltage power supply.
All I'm sayin' is try it.? Throw a gearbox in the freezer and then report back (Pretty sure you all have a few lying around).
All the best,
Dave
-- Brian?
Brian Valente portfolio
|
Re: I put a G11 gearbox in the freezer...
Hey Brian - Ain't ragging on the mount.? I love mine.? I have always used slow slew speeds as I think everything is happier that way.? I also use a higher voltage power supply.
All I'm sayin' is try it.? Throw a gearbox in the freezer and then report back (Pretty sure you all have a few lying around).
All the best,
Dave
|
Re: I put a G11 gearbox in the freezer...
I'm pretty sure Superlube tastes - like - well - grease :)? I laughed for a few after reading that!
I never intended this to be some super engineering paper where I put a gearbox on a shaker table, cool it with nitrogen,instrument the thing, throw salt at it, and measure torque.
(I have a background in T&E with aerospace systems)
My freezer is at about -10F which isn't that far from some folks operating environment.
All I really wanted to do is throw this out there.
We are always trying to get that last 1% from these awesome mounts and I think we ignore the gearboxes in the flow of power from the motor to the camera/eyepiece.
Just try it - - - I'll tell you all right now that if you simply throw a gearbox in the freezer, you will really be surprised at the increased torque to rotate the gearbox.? My MARK ONE fingers and eyeballs put it at close to an order of magnitude above room temperature.
Isn't Losmandy in Burbank CA?? Doesn't really get cold there - does it.... (I wish I was in Burbank, CA)
Clear skies and may your camera never have bad columns.
Dave
|
Michael Herman