Re: Dec motor housing loose
I had a cracked gearbox that resulted in a loose motor. Be sure to check for that, too.
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Re: Polar alignment shifts after meridian flip
For an object at the celestial equator, I don¡¯t think cone error will have any first-order impact on guiding. It shouldn¡¯t lead to the drift in declination that Magnus is seeing. This also means that drift alignment should not be affected by cone error. -Les On 20 Nov 2017, at 12:34, David Pickett yahoo@... [Losmandy_users] <Losmandy_users@...> wrote:
At 21:17 20-11-17,
jfev5mnsvqiyzpq756wvokt55jve7sbg2esr5mip@... [Losmandy_us wrote:
Isn't cone error something else? That does not
"affect" polar alignment, but causes field
rotation and similar problems. I mean, polar
alignment and drift alignment depends on the
mount, not on how the scope is mounted on the mount. Or am I wrong? Cone error is when the axis of the OTA is not
parallel to the RA axis. Then, even though the
mount is accurately polar aligned, the OTA
describes a cone around the projection of the
polar axis. Easy to visualise by imagining that a
refractor is at a 45¡ã angle to the RA axis. Then
as the axis turns the OTA will also turn and will
always be pointing somewhere else other than the NCP.
I am not sure that this explains your problem however.
But what on earth could that be? I mean, flex in
the guidescope could not possible cause this, right? If the guidescope is leaning one way before the
flip and its mounting is loose enough to make it
lean the other way afterwards, I should have
thought it quite possible that this is the reason
for your problem. At all events, I think that
_something_ is moving as the flip happens.
David
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Posted by: David Pickett <yahoo@...>
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Yahoo Groups Links
[Non-text portions of this message have been removed]
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Re: Polar alignment shifts after meridian flip
At 21:17 20-11-17, jfev5mnsvqiyzpq756wvokt55jve7sbg2esr5mip@... [Losmandy_us wrote: Isn't cone error something else? That does not
"affect" polar alignment, but causes field
rotation and similar problems. I mean, polar
alignment and drift alignment depends on the
mount, not on how the scope is mounted on the mount. Or am I wrong? Cone error is when the axis of the OTA is not parallel to the RA axis. Then, even though the mount is accurately polar aligned, the OTA describes a cone around the projection of the polar axis. Easy to visualise by imagining that a refractor is at a 45¡ã angle to the RA axis. Then as the axis turns the OTA will also turn and will always be pointing somewhere else other than the NCP. I am not sure that this explains your problem however. But what on earth could that be? I mean, flex in
the guidescope could not possible cause this, right? If the guidescope is leaning one way before the flip and its mounting is loose enough to make it lean the other way afterwards, I should have thought it quite possible that this is the reason for your problem. At all events, I think that _something_ is moving as the flip happens. David
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Re: Polar alignment shifts after meridian flip
Hi!
Isn't cone error something else? That does not "affect" polar alignment, but causes field rotation and similar problems. I mean, polar alignment and drift alignment depends on the mount, not on how the scope is mounted on the mount. Or am I wrong?
Magnus
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Re: FS: Gemini-1 and deluxe hand controller
Still Have the Gemini 1 for sale?
Mine is way flakey Greg
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Re: Polar alignment shifts after meridian flip
Isn¡¯t this a text book definition of ¡°Cone
Error¡±??
?
Not that I know anything about it..
?
Derek
?
From:
Losmandy_users@... [mailto:Losmandy_users@...]
Sent: Saturday, November 18, 2017
1:41 AM
To: Losmandy_users@...
Subject: [Losmandy_users] Polar
alignment shifts after meridian flip
?
?
Hi!
Here I am again with a new question (I am soo happy that my previous "not
performing Go To Bright Star" was solved!!!):
I'm trying to improve mu guiding (of course). So I'm experimenting a lot with
PHD2, that is what I use for guiding. Now this is some results from an
experiment yesterday:
I point the scope to the meridian, close to the equator, and run the guiding
assistant. After some 3 minutes, it tells me the polar alignment error is 0.3
arc-min (farily ok, I'd say).
Then I do a meridian flip. Point again to the meridian (that is, slewing
slightly to the east to compensate for the drift that now has occurred) . Run
the guiding assistant again. This time it reports a polar alignment error of
16.3 arc min.
So: what might be going on here? If I trust PHD2, something must be shifting.
But what on earth could that be? I mean, flex in the guidescope could not
possible cause this, right? It must be something with the mount in that case -
or am I wrong? Any suggestions on what to look for and further explore is
welcome.
And yes, this is reflected in poorer guiding after meridian flip. Interestingly
enough, guiding improves after recalibration, which again feels like a mystery.
How could calibration be affected by MF, except DEC switching direction (and
then it would go off wildly, which is not what happens - just some 50 % more
RMS).
Best,
Magnus
?
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Re: Dec motor housing loose
hi,
I'm not clear on just what may be loose.? Here are some ideas to check out: (this is for a conventional G11 or GM8, with or without OPW.? One with an Ovision may be different.)
The motor is bolted to the gearbox.? Is that loose?? if so, find and tighten it's mounting bolts or add flat washers to further compress the mounting.?
The gearbox under the motor is bolted to the mount flange.? Is that loose?? To get to that, you must first unbolt the motor from the gearbox, then tighten down the gearbox...then re-attach the motor.?
The gearbox output shaft holds one of the round Oldham coupler metal parts.? make sure that is not loose.? Make sure the other Oldham coupler metal part is tightly attached to the worm shaft.? Make sure the two Oldham metal parts are tight into the plastic center piece.? (You can loosen the worm metal piece and slide it up into the plastic part, or slide the gear end part toward the plastic part.)??
Key, especially for RA, is to ensure all the parts of the Oldham are in line along the worm axis...look in all angles to get that correct.? You my have to fiddle with the gear box mounting to get that perfected.? Offsets in Oldham axis angles to the worm axis can induce PE, which you want to drive toward zero as much as possible.? ? As far as I recall, on my CG11 and GM8, the mounting of the gearbox to its mount flange are 4-40 size.? You can often find split spring washers and flat washers of that size at hardware stores.? Or one or more flat washers could work.??
Some gear boxes are plastic, perhaps with a metal ferrule fitted, and it takes additional thought about making the mounting rigid.? ?
Hope this helps, ... Michael?
On Nov 17, 2017 5:24 PM, " puzzlewuzzle.dr@... [Losmandy_users]" < Losmandy_users@...m> wrote:
?
How may I tighten up my dec motor housing? It has an 1/8 inch or so play when I grasp the housing and wiggle. The G-11 is newly acquired so I am reluctant to try to use the drive with the looseness of the motor. The motor does run, at least it makes noise when I trigger the control button on the 492. Does the flexible plastic cover peal off to reveal the bolts? Thanks again for all the guidance and response from the group members.
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Re: Dec motor housing loose
there is wiggle in the housing, it's normal.?
I am not a mechanical expert, but i believe the iwggle is in the housing, not in the motor itself or the connections. You will always have that wiggle with the losmandy?
B
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Polar alignment shifts after meridian flip
Hi! Here I am again with a new question (I am soo happy that my previous "not performing Go To Bright Star" was solved!!!): I'm trying to improve mu guiding (of course). So I'm experimenting a lot with PHD2, that is what I use for guiding. Now this is some results from an experiment yesterday: I point the scope to the meridian, close to the equator, and run the guiding assistant. After some 3 minutes, it tells me the polar alignment error is 0.3 arc-min (farily ok, I'd say). Then I do a meridian flip. Point again to the meridian (that is, slewing slightly to the east to compensate for the drift that now has occurred) . Run the guiding assistant again. This time it reports a polar alignment error of 16.3 arc min. So: what might be going on here? If I trust PHD2, something must be shifting. But what on earth could that be? I mean, flex in the guidescope could not possible cause this, right? It must be something with the mount in that case - or am I wrong? Any suggestions on what to look for and further explore is welcome. And yes, this is reflected in poorer guiding after meridian flip. Interestingly enough, guiding improves after recalibration, which again feels like a mystery. How could calibration be affected by MF, except DEC switching direction (and then it would go off wildly, which is not what happens - just some 50 % more RMS). Best, Magnus
|
How may I tighten up my dec motor housing? It has an 1/8 inch or so play when I grasp the housing and wiggle. The G-11 is newly acquired so I am reluctant to try to use the drive with the looseness of the motor. The motor does run, at least it makes noise when I trigger the control button on the 492. Does the flexible plastic cover peal off to reveal the bolts? Thanks again for all the guidance and response from the group members.
|
Re: How much counterweight?
Hi Jim,
I had an 8" EdgeHD, round stars with an EdgeHD OTA are standard equipment. That's certainly going to be a nice setup, a bit long for my favorite subjects without the reducer and a full frame camera sensor but if you have the resources for an 11" EdgeHD and G11G ...? ?
Chip
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Re: How much counterweight?
Sold a CPC1100 and CGEM to put toward a G-11 and 11" Edge HD.? Still hope to gather the same amount of photons, just expect to get rounder stars.
Jim
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Show quoted text
-----Original Message-----
From: chiplouie@... [Losmandy_users]
To: Losmandy_users
Sent: Fri, Nov 17, 2017 2:29 pm
Subject: [Losmandy_users] Re: How much counterweight?
?
Hi Jim,
Oh, tell us what you bought so I can live vicariously! I'm broke now, between the last kid in college and a tax return surprise I did not anticipate my astro spending has to be curtailed for more than a few months. I suppose I could stop shopping and go out and use the stuff I have to capture a few photons LOL!?
Chip
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Re: G11 noise from gearbox's
Hi John,
The newer Losmandy gearboxes have bronze bushings on the axles so a drop of light machine oil on the visible bushing the best lubricant for this use. As far as a lubricant for the worm wheels and worm gears IMO the food grade (NOT the silicone version) is the best stuff for this application because it doesn't melt, separate, run, dry up and get gummy, stays soft and operational in extreme cold. A little bit goes a long way. Looks like the photo below, I buy the tub from Amazon.com and share it with my astronomy club friends.?
Chip ??
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Re: How much counterweight?
Hi Jim,
Oh, tell us what you bought so I can live vicariously! I'm broke now, between the last kid in college and a tax return surprise I did not anticipate my astro spending has to be curtailed for more than a few months. I suppose I could stop shopping and go out and use the stuff I have to capture a few photons LOL!?
Chip
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Re: G11 noise from gearbox's
On 11/17/2017 12:04 PM,
jfathers@... [Losmandy_users] wrote:
?
Hi
?
I have? a G11 with Gemini 2, which is
about for years
old.
The drive motors/gearboxes have always
made some noise when
slewing, but they appear to be coming noisier.
A friend suggested that I may need to
lubricate the
gearboxes and worms?
Is this correct?
If so what type/standard of
lubricant/grease do you
recommend?
They have not received any additional
lubricants since new.
Your advice and direction would be
greatly appreciated.
?
Kind Regards
John
UK
I have found that the bushings tend to dry out.? I usually just
open the gearbox and take some the grease from the gears(there
should be plenty) and apply to the bushings and gear shafts.
Jeff
|
Hi
?
I have? a G11 with Gemini 2, which is about for years
old.
The drive motors/gearboxes have always made some noise when
slewing, but they appear to be coming noisier.
A friend suggested that I may need to lubricate the
gearboxes and worms?
Is this correct?
If so what type/standard of lubricant/grease do you
recommend?
They have not received any additional lubricants since new.
Your advice and direction would be greatly appreciated.
?
Kind Regards
John UK
|
Re: How much counterweight?
Thanks Chip.? With luck, I made the correct guesstimate on my counterweight requirements.? Now if my back-ordered setup will just get here, I'll enjoy an early Christmas!
Jim
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Show quoted text
-----Original Message-----
From: chiplouie@... [Losmandy_users]
To: Losmandy_users
Sent: Thu, Nov 16, 2017 6:42 pm
Subject: [Losmandy_users] Re: How much counterweight?
?
Hi Jim,
The drawing and calculation method doesn't include the not insignificant weight of the counter weight shaft. so having too much weight is a possibility. I find that if I know the weight of the payload I just start with that much counterweight on the shaft and go from there. Keep us posted!
Chip
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Re: How much counterweight?
Hi Jim,
The drawing and calculation method doesn't include the not insignificant weight of the counter weight shaft. so having too much weight is a possibility. I find that if I know the weight of the payload I just start with that much counterweight on the shaft and go from there. Keep us posted!
Chip
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Re: Just purchased GM811GHD
Bill,
I had a 1992 Meade LX200 Standard Field Tripod and attached the to it using 2-3 1/4-20 cap bolts into drilled tapped holes and backed up by the 1/2"-13 threaded spreader rod. I had also done similar setups for local friends and LAAS club members with Losmandy mounts. Some of these were from 2080 and LX5/6 scopes and the center casting was threaded not machined like the LX200 which used an "E" clip on the threaded rod i a depression in the top casting which leaves the threaded 1/2"-13 rod free requiring a knob to work against the load of the upper leg spreader. But even the older non-LX200 tripods will work and need the support of a knob with a threaded insert or large nut and a fender washer to spread the load into the casting which is easily stripped out.?
This setup is just as good as the Losmandy HD tripod and once you add some ballast to the center column or wrap 5 lb Boa Bags at the bottom of each leg it's extremely solid. I'm a photographer so the sand bags are just equipment I have but you really don't need the extra weight. I've tried it many different ways and the Losmandy MA/Meade SFT works much better than the Losmandy LW Tripod any way you slice it, not as compact but pretty easy to transport. If you don't need the extension for clearance spend the money on the Losmandy MA, the 1/2"-13 knob you will need inside the MA base to lock the 1/2"-13 rod against the upper leg spreader, some 1/4-20 cap bolts and a matching drill and tap.?
Chip
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Re: Just purchased GM811GHD
Chip,?
"Based on these combinations there is no comparison when used in the real world, the LWT with the legs fully extended is much more stable than using the LWT with the 12" extension and the legs only extended to the same base mount height."
WOW, I wouldn't of thought.? But I'm glad for your real-world observations.? I'm now rethinking chasing the 12" extension.? Don't really need it for additional height for a long tube to clear tripod legs, rather was only looking at it to bring the scope a bit higher without extending the tripod legs.
I also have sitting out in the shed an original standard Meade Field Tripod (I'm assuming original 'cause it's now at 38 years old!) that served me for dozens of years with my C8.? Maybe I should consider putting it to use with a MA adapter.
Thanks Chip
... Bill ?
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Michael Herman
Bill Krosney