Re: Best Way To Raise GM811G Saddle Height?
On Mon, Mar 1, 2021 at 03:26 PM, Michael Herman wrote:
If it's just a matter of the bolt lengths, just get longer stainless steel 1/4-20 bolts
That's the issue.? My 1/4-20 Cap Screws are?hardened steel and my hacksaw can't get through it.
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Re: Best Way To Raise GM811G Saddle Height?
If it's just a matter of the bolt lengths, just get longer stainless steel 1/4-20 bolts...(at least that's the threads on my GM8 DEC).
?If the bolts are too long, you cut them to the correct length with a hacksaw and file the ends.? The dovetail mounting threads are pretty shallow.??
Best,
What¡¯s the best way to raise the height of my ADM Dovetail Saddle?? I would like more clearance between the saddle and the motors.? I am currently using a 3¡± round 1/2" thick aluminum stock but the screw lengths are not ideal for attaching the saddle.? They are either too short or long.
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Best Way To Raise GM811G Saddle Height?
What¡¯s the best way to raise the height of my ADM Dovetail Saddle?? I would like more clearance between the saddle and the motors.? I am currently using a 3¡± round 1/2" thick aluminum stock but the screw lengths are not ideal for attaching the saddle.? They are either too short or long.
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Re: Used GM-8 Guiding Help
I
have lots of thoughts about your PHD2 settings..
?
Derek
?
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From: [email protected] [mailto:[email protected]] On Behalf Of Nick
Sent: Sunday, February 28, 2021
7:59 PM
To: [email protected]
Subject: Re: [Losmandy_users_io]
Used GM-8 Guiding Help
?
Update
So I received the new gearboxes and installed on RA and Dec. I was hopeful
since they seemed to have a little less play in them compared to the ones I've
been using. I still can't shake this bad guiding, not sure if anyone has other
thoughts? I attached a few of tonight's guide logs, but looks like more of the
same. Everyone says its a mechanical issue, I just have to wonder though
because I can manually guide in PHD2 better than hysteresis and PPEC...open to
any input...feeling defeated tonight :(
?
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Re: Used GM-8 Guiding Help
All good ideas.
The puzzle is this report: The worm blocks are loose and the worm must be loose.? But the axis is sticking or the worm is sticking?
This is a used mount, right?? Maybe it's needle bearings are gummed up and not rotating???
Sounds like the internal cylindrical needle bearings are gummed up.? If they have a varnish coating on them maybe that's causing trouble?
You'd have to pull out each axis and spray in or pour in a cleaning solvent, with a rag stuffed into the bottom of the axis 1.25 inch hole, to get those needle bearings rotating freely.? Let the solvent dissolve the gum or varnish.??
You can see the needle bearings in this photo of a G11.?
The other possible trouble is a bad worm bearing.? That would be felt as the worm rotates, when the worm is not engaged. you feel a sticking point or roughness.? Consider new worm bearings R4ZZ ABEC -5 or -7...higher -7 is supposed to be better.? Look for these on with the Komodo grease packing.??
Anyway, just a few thoughts.? Else this is a strange puzzle.
Michael
On Mon, Mar 1, 2021, 8:28 AM Brian Valente < bvalente@...> wrote: I suggest you err on the side of looseness with the RA. at least you can rule out stiction then
Thanks Brian,
The DEC was an odd adjustment this go around for some reason, even with the block pushed as far away as possible the worm seemed tighter than normal, but still rotated without much effort.?I'll revisit it but I'm really wanting to focus on the RA issues. The PA error was roughly 4arcmin based on the guiding assistant which is larger than normal for me, should have spent a little more time on it.
I believe part of the issue this time was the new gearboxes don't line up with the worm/oldham very well. I'll have to enlarge the mounting holes to move it further down, I had to do the same with the old gearboxes, just wanted to try these stock before hacking away at them
I agree the RA in one direction is my main issue and I cannot figure it out. I checked just to be sure, it is on the correct mount and all the gearing is set correctly and on sidereal rate and 0.5x guide speed.?
I do gotos successfully, not last night in particular, but I have never had issues with a goto once I've built a decent model with multiple stars
A week or so ago I played with the RA divisor by setting to comet rate and doing some calculations to slow it down 0.5asec/min (I believe this came to 56127 RA Divisor) it was a little aggressive/overshoot, so maybe I would consider slowing down by 0.3asec/min (roughly 56114). When I did the the testing I had trouble with clouds and it didn't seem to have big improvements, but I can give it another shot on a clear night.
I don't think I'm over tightening...but its hard to say I guess since apparently I've never felt what a fine tuned mount feels like. I'll try loosening up some, maybe I've been too focused on "minimizing backlash" and making things too tight...I'll feel dumb and happy if this has been the problem all along!
Tonights plan: Align gearboxes better, adjust worm mesh with stiction in mind, get a better polar alignment. On a separate run play with an RA divisor of 56114. I'll update assuming weather permits
--
Brian?
Brian Valente portfolio
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Help with interpreting PHD2 log on G11
Hi!
I've recently upgraded my C8 to a C11, and accordingly, things
started becoming problematic after that....? particularly my
guiding. I have an older G11, with OPW on the RA axis. I normally
have 0.6 - 0.8" RMS before, now I struggled a lot to come below
1". Most particularly, there has turned up some new "bumps" in the
RA and in general RA RMS is around 2x DEC RMS, which is not good
for my stars (elongated).
So I have been doing polar alingment, adjusting the RA worm and
all. And finally got it all to play nicely, I get a rather smooth
curve when doing unguided gudiing assistant in PHD2 or acquiring
data in PEMPro. The PE is a bit to big (some +/- 7") but that is
not much cause for worries when it is smooth. Frequancy analysis
shows almost nothing execpt for the worm ger at 239 secs. Nice!
So I capture a PEC curve and program my mount. And I see an RMS
of about 0.5". I am a happy amateur... for a few minutes. Then
there are some "bumps" coming on the curve. Now what is this? So,
here is my question to you - what might it be that causes this?
Attached is a PHD2 log from last night. There are a lot of
sessions because I do variable stars. But session 15 is the one I
am interested in now - the long one. There are a number of big
bumps, but since most are in RA and DEC at the same time, I assume
that is external things, like a wind gust or a bird landing on the
scope.
But when I choose a section betwen those bumps
and do a frequency analysis, I get a contribution from something
that is around 60 secs. This is the one I worry about now. See the
attached screenshot from PHD2logviewer frequency analysis window.
Anyone got any idea what might cause this frequency? I know of the
76 secs and the 31.9 secs, but this one....?
Any help much appreciated.
Magnus
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Re: Used GM-8 Guiding Help
I suggest you err on the side of looseness with the RA. at least you can rule out stiction then
Thanks Brian,
The DEC was an odd adjustment this go around for some reason, even with the block pushed as far away as possible the worm seemed tighter than normal, but still rotated without much effort.?I'll revisit it but I'm really wanting to focus on the RA issues. The PA error was roughly 4arcmin based on the guiding assistant which is larger than normal for me, should have spent a little more time on it.
I believe part of the issue this time was the new gearboxes don't line up with the worm/oldham very well. I'll have to enlarge the mounting holes to move it further down, I had to do the same with the old gearboxes, just wanted to try these stock before hacking away at them
I agree the RA in one direction is my main issue and I cannot figure it out. I checked just to be sure, it is on the correct mount and all the gearing is set correctly and on sidereal rate and 0.5x guide speed.?
I do gotos successfully, not last night in particular, but I have never had issues with a goto once I've built a decent model with multiple stars
A week or so ago I played with the RA divisor by setting to comet rate and doing some calculations to slow it down 0.5asec/min (I believe this came to 56127 RA Divisor) it was a little aggressive/overshoot, so maybe I would consider slowing down by 0.3asec/min (roughly 56114). When I did the the testing I had trouble with clouds and it didn't seem to have big improvements, but I can give it another shot on a clear night.
I don't think I'm over tightening...but its hard to say I guess since apparently I've never felt what a fine tuned mount feels like. I'll try loosening up some, maybe I've been too focused on "minimizing backlash" and making things too tight...I'll feel dumb and happy if this has been the problem all along!
Tonights plan: Align gearboxes better, adjust worm mesh with stiction in mind, get a better polar alignment. On a separate run play with an RA divisor of 56114. I'll update assuming weather permits
-- Brian?
Brian Valente portfolio
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Re: Used GM-8 Guiding Help
Thanks Brian,
The DEC was an odd adjustment this go around for some reason, even with the block pushed as far away as possible the worm seemed tighter than normal, but still rotated without much effort.?I'll revisit it but I'm really wanting to focus on the RA issues. The PA error was roughly 4arcmin based on the guiding assistant which is larger than normal for me, should have spent a little more time on it.
I believe part of the issue this time was the new gearboxes don't line up with the worm/oldham very well. I'll have to enlarge the mounting holes to move it further down, I had to do the same with the old gearboxes, just wanted to try these stock before hacking away at them
I agree the RA in one direction is my main issue and I cannot figure it out. I checked just to be sure, it is on the correct mount and all the gearing is set correctly and on sidereal rate and 0.5x guide speed.?
I do gotos successfully, not last night in particular, but I have never had issues with a goto once I've built a decent model with multiple stars
A week or so ago I played with the RA divisor by setting to comet rate and doing some calculations to slow it down 0.5asec/min (I believe this came to 56127 RA Divisor) it was a little aggressive/overshoot, so maybe I would consider slowing down by 0.3asec/min (roughly 56114). When I did the the testing I had trouble with clouds and it didn't seem to have big improvements, but I can give it another shot on a clear night.
I don't think I'm over tightening...but its hard to say I guess since apparently I've never felt what a fine tuned mount feels like. I'll try loosening up some, maybe I've been too focused on "minimizing backlash" and making things too tight...I'll feel dumb and happy if this has been the problem all along!
Tonights plan: Align gearboxes better, adjust worm mesh with stiction in mind, get a better polar alignment. On a separate run play with an RA divisor of 56114. I'll update assuming weather permits
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Re: Losmandy Polar scope calibration
are good to have on hand. The .028" grubs are found on some encoder interrupters. Eklind also has a
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Re: G11 Drive Gear Removal
Sorry to read that.? I had the same experience in one G11 tucked motor system, and I gave up trying to get one of the gears off.??
I suggest you contact the factory for their guidance on this problem.? They should have replacement gears in case one gets damaged.??
I was able sometimes to get a small enough flat top screwdriver in small problem setscrews and turn the setscrew out.? ? Sometimes only the top of the setscrew is stripped and deeper in it is possible to get the right hex key wrench in....you might have to try and tap the wrench in with a small hammer to get it to the bottom.? ??
It is a problem that these tiny setscrews come in many gears and other parts you buy.? They are just too small...if the threads seize you are stuck.? It would be better if the tiny setscrew were removed on the original gear and before assembly on the mount, the hole enlarged and tapped for a larger hex setscrew, so they don't strip so easily. I prefer 4-40 minimum size.? This is extra work but makes disassembly and repair possible instead of the alternative...drill out the existing setscrew and chance damaging something.? I did this on some of my polar scopes, and other astronomy parts too because the adjustment setscrews were impossibly tiny.? The pole master for example comes with a very tiny allen wrench for some setscrew they used in that.??
Good luck, Michael
Michael,
Looking at these set screws under high magnification, it does seem they are stripped internally and are no longer a perfect hex shape. I don't see a way to easily remove the gears without drilling out the screw or pulling off under force. Either way I wouldn't want to attempt this until a had some replacement gears on hand. For anyone replacing a gearbox with the Losmandy original, or any alternative you have in mind, this one small screw may prove to be a challenge.
Best regards,
John
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Re: G11 Drive Gear Removal
Michael,
Looking at these set screws under high magnification, it does seem they are stripped internally and are no longer a perfect hex shape. I don't see a way to easily remove the gears without drilling out the screw or pulling off under force. Either way I wouldn't want to attempt this until had some replacement gears on hand. For anyone replacing a gearbox with the Losmandy original, or any alternative you have in mind, this one small screw may prove to be a challenge.
Best regards,
John
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Re: Used GM-8 Guiding Help
Hi Nick
Your DEC axis shows stiction, so it seems like you may have it too tight there? it also looks like your polar alignment may be quite a bit off since DEC continues to want to drift downwards
Regarding mechanical, the logs don't lie. your main period PE is nearly 25" peak to peak, which is pretty huge
I can't help but focus on seeing your RA in one direction only.?
just for testing purposes, you might triple check the correct mount type (i know, but) and also confirm the gearing is set correctly for a G8
have? you also done gotos successfully, or just slewed around?
you could also try experimenting with adjusting the RA divisor to see if a slightly different rate will help on this. It also looks like you may have stiction on the RA axis as well. it seems to snap back every once in a while. are you overtightening thingts? :)
?
>>>I just have to wonder though because I can manually guide in PHD2 better than hysteresis and PPEC
it might feel that way, but you are guiding at around 1 pixel accuracy, so I don't know if your manual guide would be that much better
Update
So I received the new gearboxes and installed on RA and Dec. I was hopeful since they seemed to have a little less play in them compared to the ones I've been using. I still can't shake this bad guiding, not sure if anyone has other thoughts? I attached a few of tonight's guide logs, but looks like more of the same. Everyone says its a mechanical issue, I just have to wonder though because I can manually guide in PHD2 better than hysteresis and PPEC...open to any input...feeling defeated tonight :(
-- Brian?
Brian Valente portfolio
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Re: Used GM-8 Guiding Help
Update
So I received the new gearboxes and installed on RA and Dec. I was hopeful since they seemed to have a little less play in them compared to the ones I've been using. I still can't shake this bad guiding, not sure if anyone has other thoughts? I attached a few of tonight's guide logs, but looks like more of the same. Everyone says its a mechanical issue, I just have to wonder though because I can manually guide in PHD2 better than hysteresis and PPEC...open to any input...feeling defeated tonight :(
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Re: G11T vs AstroPhysics - opinions wanted
Wow, I hadn't thought about the tooth count.? Duh!
Thanks for pointing that out....? that may be the deciding factor.
al
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Re: G11T vs AstroPhysics - opinions wanted
Worm gear diameter and tooth count, all things being equal, are the imost mportant items to consider in tracking and payload capacity. A balanced design is more important than outright mechanical strength. This is why the G11 is a better mount.
--
Chip Louie Chief Daydreamer Imagination Hardware?
? ?Astropheric Weather Forecast - South Pasadena, CA?
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Re: G11T vs AstroPhysics - opinions wanted
Al,
One very important consideration for you should be the camera you are using or planning to use: the size of the pixels of your camera would limit the focal length of your telescope.
For instance, I am using ST8300 with 5.4um pixels, which gives 0.5"/pixels at 2000mm FL with my 10" RC.?
0.5"/pixel is probably the highest resolution you should be looking at for imaging DSO - any higher resolution and seeing would?impact image quality.?
My G11 is able to handle my 10" RC, which weighs about #40, although it is a little marginal.
If you have a camera with smaller pixels, no point in going with a larger scope, like 12" RC.
The only reason you may want a bigger scope is if you have one of those old cameras with 9um pixels, only in that case you need a bigger/better mount, otherwise, G11 should be fine.
BTW, I think that mechanically, CGE is actually stronger than G11. The problem with CGE is that it has 180 teeth on the worm gear, whereas G11 has 360.
Alex
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Re: Losmandy Polar scope calibration
Thanks all for the info. Looks like I'll be calibrating. Amazon has the 0.9mm...ordered and on the way.
Bob
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Re: Losmandy Polar scope calibration
Celestron has a polar scope alignment "how to" that will work with any polar scope. I like it because celestron breaks it down to simple steps with graphics.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://s3.amazonaws.com/celestron-site-support-files/support_files/1223669429_polaraxixfinder.pdf&ved=2ahUKEwjD8rGrqI3vAhUMQK0KHcwHCNoQFjAAegQIARAC&usg=AOvVaw076vH0ziID6s_0497-n6xC
It's a pdf file
Chuck On Sunday, February 28, 2021, 11:22:44 AM PST, Michael Herman <mherman346@...> wrote:
Hi Bob,
All these optical polar scopes have a moveable glass reticle (also spelled reticule) that is centered (you must do this centering optically) with 3 tiny setscrews. Sometimes the setscrews have a flat screwdriver slot, and sometimes they have a tiny allen head.??
First thing to do is focussing the optical parts: First focus the eyepiece on the reticle markings. Then unlock and screw in and out the long barrel at the end of the polar scope, until a star (or very far object like a distant treetop) is in focus. When done, both the reticle and the faraway object are both in focus for your vision.??
Next thing to do is adjust the reticle position... The key thing to know is that the reticule is glass and can be cracked...instantly... by too much pressure from the metal setscrew.? So you must back out one setscrew before you tighten down another one.? It is very tedious?to do this ... like adjusting the secondary mirror of an SCT which is a similar iterative process.??
You point your RA at a convenient target like a faraway treetop, in the daytime.? You rotate the RA axis and watch the "+" symbol that is the center of the reticle markings.? You watch that "+" symbol move.? You want to adjust the reticle position with the 3 setscrews?until you about center the "+" sign as best as possible when the RA axis rotates.? I put the?+ sign on the top of the tree when the tree image is focussed.
Now here's the rub:? It is often observed that if you loosen the front locking round black disk that holds on the polar scope... and you rotate the polar scope, that the?+ sign will no longer be centered!? This is the common observation.? This means you want to keep that polar scope in its place on the RA of the mount, or at least mark its orientation with some method (white labelmaker?tape cut in triangles works for me.)? ?But this is not the way the Losmandy polar scope is supposed to work...it is supposed to be rotated to line up Cassiopeia?or the Big Dipper and a few stars near polaris.? So... you must judge what to do.
There is a website with info about this polar scope, but it lacks the details about about practical matters.??
The better approach is to get a Polemaster electronic imaging pole camera and lens. This works very nicely, and saves your back and eyeballs.? But it is not free...naturally.? ?
All the best, Michael
On Sun, Feb 28, 2021 at 11:05 AM TeleGizmos < sales@...> wrote: Just received my GM811G, assembly complete, went quite well. Installed and checked the polar scope alignment and it's a bit out of calibration to the mount. Question is for visual observing only, how critical is spot on polar scope calibration to the mount? I know how perform calibration on a polar scope but have never bothered to concern myself with this in the past. However, this is the first mount I've owned that is go-to and want the go-to to be accurate.
If the consensus is to calibrate the polar scope, how does the Losmandy scope adjust? I can see the three opposing adjustment points however they are extremely?small openings and do not appear (under magnifying glass) to have turn-ability...as in I can not see allen screw heads or slotted screw heads.
Your help is appreciated.?
Cheers,
Bob Pitney
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Re: Losmandy Polar scope calibration
When I first got my G11, the polar scope was not well-calibrated, and as a result, I was building a model to improve go-to accuracy. Once I calibrated the polar scope, I found I merely had to do a 1-star alignment and my go-to was just fine for my visual observing.
You do need a 0.9mm Allen wrench to adjust those tiny grub screws. I could not find that at my local hardware store and had to order from McMaster-Carr (which kind of stung because there is a minimum shipping charge). Be very careful not to exert any pressure on the glass reticle because it will shatter - use very gentle fingertip pressure and be sure to loosen 1 or 2 screws before tightening the opposing one. I found it was really quite easy and quick to get it nicely calibrated, but just be careful not to exert pressure on the reticle.
-Bill
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Re: PREVIEW Part 3 of Practical Periodic Error Correction
Hi Michael
thanks for your feedback
For any future feedback on specific videos It would be great if you could start a new thread here, or better yet add your comments to the youtube?video itself. I fear your input will be buried in a thread that won't be easily found in the future
On Sun, Feb 28, 2021 at 11:08 AM Michael Herman < mherman346@...> wrote: Dear Brian,
Thank you for sharing these pre-released episodes?with me. Your experience with video shows... the Jetsons theme music is cute.??
I watched one recently on balancing?the scope load.? On that one I'd add these points:
1. put the mount at CWD and tighten down the RA clutch, before putting on or taking off the scope.?? 2. Always put or or take off the scope after the counterweights are in place...Never put on a heavy scope when the system has no counterweights.?? 3. Add all your weights to the counterweight bar before you put the scope on. 4. After you add the weights, put the "toe saver" bolt into the end of the counterweight bar.? 5. Soon as you put the scope dovetail in after the weights are on, put in the front 1/4-20 bolt to prevent it from accidentally?slipping out.? 6. Gemini-2 has a "balance" indicator (Menu / Mount / Balance).? ?Put the counterweight bar horizontally, then look at the balance indicator on the Gemini-2 unit.? Use the indicator to help perfect balance.
I'll look at the other videos when I can.? I still have to get my G-2 unit internet connected!? I did get one of those yellow Internet wireless boxes and I used them to connect my older Pioneer receivers to get internet radio.? Now to use one for the Gemini-2 too.??
__________
One of the two new gearboxes I got from you has a tight spot in the gearbox rotation. Feeling the rotation by hand, it has a slight tightness on one spot, but not as bad as another gearbox (the RA gearbox of the G11T that I got).? The other gearbox I got from you seems better.??
I suggest you hand rotate the output shaft of your stock of gearboxes and look for ones that have this tight spot in the drive axle rotation.? Surprisingly this stuff does show up in the PE because the Gemini motor and Gemini drive is sensitive to its drive current.? If you find defective gearboxes, you can complain to your supplier as you have volume purchasing power.??
Stay well and safe, Michael
On Tue, Jul 7, 2020 at 11:00 PM Brian Valente < brian@...> wrote: Preview just for you! ? This covers the basic PEMPro settings for data collection ?
? I felt a bit rushed so let me know if this content works for you ? ? ? Thanks ? Brian ? Brian Valente Losmandy Astronomical ? Losmandy.com Tutorials and vids at ?
--
-- Brian?
Brian Valente portfolio
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Michael Herman
Chip Louie