Ap-1600 Re-Greasing Experience


Emilio J. Robau, P.E.
 

I think I am in my fourth or fifth year of operating my 1600.  What can you say, love it.   Anyways I was overdue for a greasing for sure since I use it every winter, from about November 1 to May 15th and had not re-greased it yet.  It was overdue for a re-greasing.   I went to Walmart and purchased a tube of grease that was on sale for about $9.   

Just kidding.  I purchased the nice package offered by AP.   The instructions were clear and easy to follow.   The procedure was straight forward.   Everything went great except that one of my bolts for the clamp up against the dovetail dropped into the access whole which I had open.  Took me 45 minutes to find the thing.  All I could think of was George telling me on the phone to make sure I be careful about the bolts. 

I have the 1600 that does not have the automatic meshing.   RA meshing was easy.  Dec is a huge pain in the rear for me.   My Dec assembly is very sensitive especially to gear meshing and gear bolt tightening.   

I judge how well everything is meshed by the sounds of the motors.  I like them smooth with no sound of oscillation, no slight clunking, no ticking, no slowing and speeding, and with a nice constant robotic moving sound and no whining!  I don't know if that is the way it is supposed to be, but that is how I judge things.  After a while, I got the Dec back into shape.   I think everything sounds good.  Slews fine.

I cleaned everything with mineral spirits and denatured alcohol as prescribed by the Doctor. 

I did deviate from the instructions a bit.   I went ahead and left my equipment on and had faith in my balancing scheme even though I have an array and they are somewhat naturally unbalanced depending on what you have on it and where you are in the sky.  I actually did this out of laziness in that I just did not want to tear down three scopes and three cameras and three of everything.  That would take me two days to reassemble and jigger USB cords to get everything working again.

However, there was a unintended consequence of this laziness.  For the first time, I actually learned that my fish scale balancing technique often touted here worked pretty darn well.  The RA was almost in perfect balance.   I did not expect to feel how smooth this mount really is without the motors engaged.   I wish there was a way to manually disengage them.   Anyways, I shifted a weight about 1 inch and the scope was perfect in RA.   MY DEC axis was actually spot on.  The take away is that if you are curious about your balance if you don't have the newer motor boxes disengage the motor boxes and leave your equipment mounted.  You might want someone else around when you do this.  Now Roland says you can be way off and it will be fine.   I understand, but most of us are tinkerers and we just can't leave what appears to be well and good alone until proven well and good.

I also wanted to relay how beneficial being able to take things apart was, and see how everything matched up and how the motor box was mounted.  It was a great learning experience, so don't delay too much, you will learn quite a bit about your mount when you do this maintenance activity.

I am about to try things out and test guide again.  I suppose I will do another PE curve with Ray's fine software.

Losing the bolt in the mount was a downer, but overall, it was a great learning experience.   Highly recommended.


michael mccann
 

Great report! Now I have not heard of the fish scale test. I suspect I understand, but is there a link to the description?

Cheers


Emilio J. Robau, P.E.
 

Basically you use a small electronic fish scale.   I purchased one for about 10 bucks on Amazon. Use this to measure the weight reading as you pull up and down on both Dec and RA.   Make sure your moment arm is equal and pick a spot of equal distance from the centroid of the mount and match the reading pulling up and down.  Once you do that you should be well balanced.   There is an extended set of steps for array mounts with multiple telescopes like mine.   However, I will spare you the details on that one since I do think there is a write up somewhere.


Craig Young
 

I was not as fortunate.  My 1600 w/auto adjusting worm mesh, is about 5 years old and I am putting a new OTA on it.  So I figured while switching telescopes I would service the mount, including re-greasing the RA and DEC worm gear.  The greasing part went well, got the old grease off and the new grease went on without a hitch.  To do this I had to remove both the RA and DEC motors.  I got instructions on how to do this from AP which went perfectly.  And now the BUT.  Following the motor install instructions from AP to the T (several times) I put the motors back on and now the mount sounds like a machine shop cutting pipes.  As another user reported, this sounds like my iOptron CEM60 when you re-mesh the worm too tight and have to back it off a bit.  This happens so often with the CEM60 that iOptron provided a procedure on how to fix it.  I have not found such a procedure yet from AP.

I have attached an audio recording of what it sounds like.  The setup is the 1600 without any OTA and CW bar.  But it does have the DEC saddle on it and is in the Park 3 position.  I tested only the DEC motor since it is not balanced in RA but is perfectly balanced in DEC.  I ran the APJog utility from AP which connects to the V2 ASCOM driver and to the mount.  Once connected to the mount I unparked the scope from the last park position.  Move speed was set to 64x for the first test.  Pressing first the "N" button and then the "S" button you can hear the DEC motor as it moves (Test 1).  After the test I clicked the Park button (APJog) to park the scope at the current position.  Clearly the mesh is too tight, but without any instructions on what to do in this case I blindly tried lots of things.

For Test 2, I moved the worm engagement lever to half way so it was still engaged but could be disengaged by hand.  I loosened the attachment bolts (3 of them) and then pulled back on the motor to full disengage it.  With the motor manually disengaged I tightened the attachment bolts and then fully engaged the lever on the side.  The idea here was to try and back off the worm a bit and yet have the engagement lever in the fully engaged position.  I did a new recording at 64x move speed and you can hear the noise is pretty much gone.  I then changed the move speed to 200x (Test 3) and repeated the N and S moves.  As you can hear, the noise is really bad.  So in this state it moves correctly N and S at 64x but makes a horrible sound at 200x.  I am guessing it is some sort of resonance?

George has had me try several other things but so far nothing as worked.  Hopefully this week, between George and other users who have experienced this problem (from the Youtube videos and Forum postings), there will be a modified procedure for attaching the motor to the mount or a method to tweak the motor afterwards (similar to what iOptron did) to get the motors sounding smooth again and help others who run into the same problem.

Craig



Steven
 

No question about it, it would break anyone's heart. I'm sad to hear this and somewhat reluctant to do the grease on my own mount, although i've seen the video - it looks too easy. I'd be interested in the outcome.

S


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Craig Young <craig.young.m8@...>
Sent: Monday, 24 January 2022 7:59 pm
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] Ap-1600 Re-Greasing Experience
 

I was not as fortunate.  My 1600 w/auto adjusting worm mesh, is about 5 years old and I am putting a new OTA on it.  So I figured while switching telescopes I would service the mount, including re-greasing the RA and DEC worm gear.  The greasing part went well, got the old grease off and the new grease went on without a hitch.  To do this I had to remove both the RA and DEC motors.  I got instructions on how to do this from AP which went perfectly.  And now the BUT.  Following the motor install instructions from AP to the T (several times) I put the motors back on and now the mount sounds like a machine shop cutting pipes.  As another user reported, this sounds like my iOptron CEM60 when you re-mesh the worm too tight and have to back it off a bit.  This happens so often with the CEM60 that iOptron provided a procedure on how to fix it.  I have not found such a procedure yet from AP.

I have attached an audio recording of what it sounds like.  The setup is the 1600 without any OTA and CW bar.  But it does have the DEC saddle on it and is in the Park 3 position.  I tested only the DEC motor since it is not balanced in RA but is perfectly balanced in DEC.  I ran the APJog utility from AP which connects to the V2 ASCOM driver and to the mount.  Once connected to the mount I unparked the scope from the last park position.  Move speed was set to 64x for the first test.  Pressing first the "N" button and then the "S" button you can hear the DEC motor as it moves (Test 1).  After the test I clicked the Park button (APJog) to park the scope at the current position.  Clearly the mesh is too tight, but without any instructions on what to do in this case I blindly tried lots of things.

For Test 2, I moved the worm engagement lever to half way so it was still engaged but could be disengaged by hand.  I loosened the attachment bolts (3 of them) and then pulled back on the motor to full disengage it.  With the motor manually disengaged I tightened the attachment bolts and then fully engaged the lever on the side.  The idea here was to try and back off the worm a bit and yet have the engagement lever in the fully engaged position.  I did a new recording at 64x move speed and you can hear the noise is pretty much gone.  I then changed the move speed to 200x (Test 3) and repeated the N and S moves.  As you can hear, the noise is really bad.  So in this state it moves correctly N and S at 64x but makes a horrible sound at 200x.  I am guessing it is some sort of resonance?

George has had me try several other things but so far nothing as worked.  Hopefully this week, between George and other users who have experienced this problem (from the Youtube videos and Forum postings), there will be a modified procedure for attaching the motor to the mount or a method to tweak the motor afterwards (similar to what iOptron did) to get the motors sounding smooth again and help others who run into the same problem.

Craig



Andrew J
 

On Sun, Jan 23, 2022 at 08:44 PM, Emilio J. Robau, P.E. wrote:
Use this to measure the weight reading as you pull up and down on both Dec and RA.   Make sure your moment arm is equal and pick a spot of equal distance from the centroid of the mount and match the reading pulling up and down.  Once you do that you should be well balanced.
I am still trying to visualize how this works in practice. When you say "pull up and down on both Dec and RA", what do you mean? Hook the scale to the end of the dew cap or end of camera on the DEC Axis? End of weight bar, top of scope for RA? Can you expand a bit on how this works. I would like to give it a try.


Emilio J. Robau, P.E.
 

Craig,

Very interesting report and I will follow the progress if you are kind enough to continue to document your activities.    I think for some reason the DEC motor meshing on my mount is also very touchy.  I did spend quite a bit of time on it last night and although I think I have good meshing, I still have some doubt.   I think you indicated that you had the newer motor box.  My mount must be older, because I don't have the newest motor box that allows a free movement of the mount so you can attain perfect balance even though it does not really have to be perfect.

One of the things I noticed on my mount is that George told me to adjust meshing in  out ever so slightly in our out so you eliminate backlash (ability to slightly move the mount without engaging the motors) yet don't apply too much engagement pressure.   I did this repeatedly and I noticed that I would adjust the spacing on the mesh so that the spur gear was easy to turn.   Then when I went back and slewed at higher speeds, the spur gears would get tight again.   I thought this was not right so I did it several times.  It seems like they get stuck and then all of a sudden they free up and the gears turn easy.   All of this is done with the cap off the box to expose the gears.  After a while I gave up on the notion that the spur gears would run easily when well meshed and ended up getting them to run easily and then placed the cap back on and tested everything out.

Certainly you do have an issue and I have some lingering doubt about my DEC meshing.   RA meshing seems to be perfect.  That motor sings a steady and constant song with no oscillations and it sounds like I think it should.  DEC is almost the same, but it does not sound the same as RA.  Also, the sticking points on my mount are around the pole as the mount shifts pointing location.

Anyways, constructive documentation of your issue will be helpful to those that come behind us with this issue.

Thanks



Emilio J. Robau, P.E.
 

For Dec rotate the telescope so that it is horizontal  the ground and any movement of the scope is perpendicular to the ground.   Find something to hook the scale on to and pull down and read the force vector (weight, I forget my physics in my old age) on the scale.  Then do the exact same thing pulling up with the scale.  The weight needs to match so you move the scope back and forth to balance DEC.

 

For RA I do the same thing and manually slew the telescope to the east side so it is parallel to the ground, but I usually use the end of the weight bar to do the measurement.   I measure the force that it takes to move the scope up.  Just at the point where you overcome friction.  I then do the same and measure the force that it takes to move it down, just as you break friction.  I adjust the weights accordingly.

 

It is kind of the same thing you do to balance the scope manually but, you use a scale to get a more accurate indicator of what force is needed to move the scope just after you break friction.

 

I hope this helps.   It is working for me.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Andrew J
Sent: Monday, January 24, 2022 10:16 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Ap-1600 Re-Greasing Experience

 

On Sun, Jan 23, 2022 at 08:44 PM, Emilio J. Robau, P.E. wrote:

Use this to measure the weight reading as you pull up and down on both Dec and RA.   Make sure your moment arm is equal and pick a spot of equal distance from the centroid of the mount and match the reading pulling up and down.  Once you do that you should be well balanced.

I am still trying to visualize how this works in practice. When you say "pull up and down on both Dec and RA", what do you mean? Hook the scale to the end of the dew cap or end of camera on the DEC Axis? End of weight bar, top of scope for RA? Can you expand a bit on how this works. I would like to give it a try.


Andrew J
 

On Mon, Jan 24, 2022 at 07:38 AM, Emilio J. Robau, P.E. wrote:

For Dec rotate the telescope so that it is horizontal  the ground and any movement of the scope is perpendicular to the ground.   Find something to hook the scale on to and pull down and read the force vector (weight, I forget my physics in my old age) on the scale.  Then do the exact same thing pulling up with the scale.  The weight needs to match so you move the scope back and forth to balance DEC.

 

For RA I do the same thing and manually slew the telescope to the east side so it is parallel to the ground, but I usually use the end of the weight bar to do the measurement.   I measure the force that it takes to move the scope up.  Just at the point where you overcome friction.  I then do the same and measure the force that it takes to move it down, just as you break friction.  I adjust the weights accordingly.

 

It is kind of the same thing you do to balance the scope manually but, you use a scale to get a more accurate indicator of what force is needed to move the scope just after you break friction.

 

I hope this helps.   It is working for me.

@Emilio Thanks for the explanation. I think i understand now. Just use  the scale to pull up/down on the end of the weight bar for RA and probaly the end of the camera near focus for DEC. Makes sense. I am placing an amazon order for a fish scale now.


Roland Christen
 

Our mount tech, Dave, her at the factory would be the person to talk to. He can help you set your gearbox so it runs smoothly. Just call the office and ask to speak to Dave about your mount, and they will patch you thru to Dave.

Roland

-----Original Message-----
From: Craig Young <craig.young.m8@...>
To: main@ap-gto.groups.io
Sent: Mon, Jan 24, 2022 12:59 am
Subject: Re: [ap-gto] Ap-1600 Re-Greasing Experience

I was not as fortunate.  My 1600 w/auto adjusting worm mesh, is about 5 years old and I am putting a new OTA on it.  So I figured while switching telescopes I would service the mount, including re-greasing the RA and DEC worm gear.  The greasing part went well, got the old grease off and the new grease went on without a hitch.  To do this I had to remove both the RA and DEC motors.  I got instructions on how to do this from AP which went perfectly.  And now the BUT.  Following the motor install instructions from AP to the T (several times) I put the motors back on and now the mount sounds like a machine shop cutting pipes.  As another user reported, this sounds like my iOptron CEM60 when you re-mesh the worm too tight and have to back it off a bit.  This happens so often with the CEM60 that iOptron provided a procedure on how to fix it.  I have not found such a procedure yet from AP.

I have attached an audio recording of what it sounds like.  The setup is the 1600 without any OTA and CW bar.  But it does have the DEC saddle on it and is in the Park 3 position.  I tested only the DEC motor since it is not balanced in RA but is perfectly balanced in DEC.  I ran the APJog utility from AP which connects to the V2 ASCOM driver and to the mount.  Once connected to the mount I unparked the scope from the last park position.  Move speed was set to 64x for the first test.  Pressing first the "N" button and then the "S" button you can hear the DEC motor as it moves (Test 1).  After the test I clicked the Park button (APJog) to park the scope at the current position.  Clearly the mesh is too tight, but without any instructions on what to do in this case I blindly tried lots of things.

For Test 2, I moved the worm engagement lever to half way so it was still engaged but could be disengaged by hand.  I loosened the attachment bolts (3 of them) and then pulled back on the motor to full disengage it.  With the motor manually disengaged I tightened the attachment bolts and then fully engaged the lever on the side.  The idea here was to try and back off the worm a bit and yet have the engagement lever in the fully engaged position.  I did a new recording at 64x move speed and you can hear the noise is pretty much gone.  I then changed the move speed to 200x (Test 3) and repeated the N and S moves.  As you can hear, the noise is really bad.  So in this state it moves correctly N and S at 64x but makes a horrible sound at 200x.  I am guessing it is some sort of resonance?

George has had me try several other things but so far nothing as worked.  Hopefully this week, between George and other users who have experienced this problem (from the Youtube videos and Forum postings), there will be a modified procedure for attaching the motor to the mount or a method to tweak the motor afterwards (similar to what iOptron did) to get the motors sounding smooth again and help others who run into the same problem.

Craig



--
Roland Christen
Astro-Physics


Craig Young
 

Emilio,
I have finally found a solution for meshing the gears and now I can slew the telescope with no noise.  I created a new topic with my procedure so as not to digress from your original topic

Craig


Emilio J. Robau, P.E.
 

It is kind of like the way you would normally balance by getting the feel of the imbalance by positioning the scope in the proper position to push up and down to see which side needs more weight.  You just use a cheap digital fish scale instead of your "feel" judgement.   Once you break friction, keep moving it a bit and look at the reading in the both up and down direction.


Emilio J. Robau, P.E.
 
Edited

Last night I completed the re-greasing process, which in my case included the development of a PEC curve to check performance of the re-greased mount.   Upon the first try I let the worm go through four cycles and I observed a 3 to 5 arc-sec irregular jump at one of the locations in the worm period.    I panicked and then went to the mount and re-meshed the RA gears which were not really altered except to re-install them.  I used the published pdf procedure and banged on the box.   I went back and remeasured the PE utilizing Pempro of course.   Everything smoothed out and my error with a quibic (sp?) fit was 3 arc sec peak to bottom of the curve.   

I updated the mount PE curve for PEC.  I ran another three cycles and was disappointed to see that the PEC was now 6 arc-sec.   I then inverted the curve and tried to retransmit the inverted curve.   However, something did not seem correct in that upon pressing the to the mount button in Pempro on the APraw tab nothing seemed to happen.   I ran the test and it was again 6 arc-sec.   I was mystified why I could not transmit the curve to the mount.   

I disconnected the scope and reconnected.   I then wen to the AP Raw tab in Pempro and tried to send the inverted curve to the mount.   This time it did transmit the data as evidenced by the pop up that indicated it was transmitting.

I then ran four worm cycles and the results WERE SPECTACULAR.   I could not even develop a new PE curve of the corrected tracking because there was no real definable cycle.  All looked like random seeing issues and the data ossiclated from 0 to 2 arc-seconds.  

So, I am finished.   I just have one more trivial question for George to give me a full understanding of the expected performance of the mechanisms when taken apart.

All in all, a great learning experience.

I do have one question for everyone.   Now that I have what is apparently ultra low corrected PE, I suppose I can forgo guiding for a yet undetermined exposure limit on my subs.  I would say two to three minutes for sure.  However, what happens to the drift?  I am pretty well aligned but I do still have some drift.  Does the selection of relatively short exposure times take care of the drift so that it is not meaningful and the PEC takes care of the PE?  I think that is the answer.  If you don't guide, how the heck can you dither?  I always guide, but this last exercise has reinforced the ability to not guide.  

Thanks in advance for any replies.


 

Hi Emilio

Unguided really depends on duration and focal length, without that info it's a bit of shooting in the dark. On my 1600 i can do 15 min unguided subs at 400mm focal length, but nothing close to that on the 20" @ 3500mm

If you want to do unguided, i suggest an all sky model via APCC Pro would be a great addition. it will help compensate for the next level of tracking issues (polar misalignment, refraction, etc.) now that you have PE under control



On Tue, Jan 25, 2022 at 8:02 AM Emilio J. Robau, P.E. <ejr@...> wrote:
Last night I completed the re-greasing process, which in my case included the development of a PEC curve to check performance of the re-greased mount.   Upon the first try I let the worm go through four cycles and I observed a 3 to 5 arc-sec irregular jump at one of the locations in the worm period.    I panicked and then went to the mount and re-meshed the AR gears which were not really altered except to re-install them.  I used the published pdf procedure and banged on the box.   I went back and remeasured the PE utilizing Pempro of course.   Everything smoothed out and my error with a quibic (sp?) fit was 3 arc sec peak to bottom of the curve.   

I updated the mount PE curve for PEC.  I ran another three cycles and was disappointed to see that the PEC was now 6 arc-sec.   I then inverted the curve and tried to retransmit the inverted curve.   However, something did not seem correct in that upon pressing the to the mount button in Pempro on the APraw tab nothing seemed to happen.   I ran the test and it was again 6 arc-sec.   I was mystified why I could not transmit the curve to the mount.   

I disconnected the scope and reconnected.   I then wen to the AP Raw tab in Pempro and tried to send the inverted curve to the mount.   This time it did transmit the data as evidenced by the pop up that indicated it was transmitting.

I then ran four worm cycles and the results WERE SPECTACULAR.   I could not even develop a new PE curve of the corrected tracking because there was no real definable cycle.  All looked like random seeing issues and the data ossiclated from 0 to 2 arc-seconds.  

So, I am finished.   I just have one more trivial question for George to give me a full understanding of the expected performance of the mechanisms when taken apart.

All in all, a great learning experience.

I do have one question for everyone.   Now that I have what is apparently ultra low corrected PE, I suppose I can forgo guiding for a yet undetermined exposure limit on my subs.  I would say two to three minutes for sure.  However, what happens to the drift?  I am pretty well aligned but I do still have some drift.  Does the selection of relatively short exposure times take care of the drift so that it is not meaningful and the PEC takes care of the PE?  I think that is the answer.  If you don't guide, how the heck can you dither?  I always guide, but this last exercise has reinforced the ability to not guide.  

Thanks in advance for any replies.



--
Brian 



Brian Valente


Emilio J. Robau, P.E.
 

Thanks Brian,

I do have a model built with APPM and pointing is superb.  Even with an clear across the meridian flip it only takes one adjustment by ASTAP and NINA to get me spot on.  My master scope on the array images at 2000mm with an OAG.  My two slaves image at about 750 mm and 489 mm.   I am thinking that if I have even better polar alignment, I could just about eliminate drift and could go longer in the 2000mm subs.  I think three minutes is acceptable at this time even with my current polar alignment, since the drift will probably not show.  Certainly on the lower fl scopes on the same mount array.   If I tweak the polar alighment, I maybe able to go even longer.  I guess what I am saying is that the polar alignment is now controlling my sub length due to drift.  Is this correct?

Finally, how do you dither?.


 

An all sky model in APPM is not just for pointing correction, it's for tracking correction as well, and it will compensate for polar misalignment. 

For dithering, i use an option in SGP "Direct Mount Guider" which is exactly what you need for dithering without guiding

image.png


On Tue, Jan 25, 2022 at 8:16 AM Emilio J. Robau, P.E. <ejr@...> wrote:
Thanks Brian,

I do have a model built with APPM and pointing is superb.  Even with an clear across the meridian flip it only takes one adjustment by ASTAP and NINA to get me spot on.  My master scope on the array images at 2000mm with an OAG.  My two slaves image at about 750 mm and 489 mm.   I am thinking that if I have even better polar alignment, I could just about eliminate drift and could go longer in the 2000mm subs.  I think three minutes is acceptable at this time even with my current polar alignment, since the drift will probably not show.  Certainly on the lower fl scopes on the same mount array.   If I tweak the polar alighment, I maybe able to go even longer.  I guess what I am saying is that the polar alignment is now controlling my sub length due to drift.  Is this correct?

Finally, how do you dither?.



--
Brian 



Brian Valente


Emilio J. Robau, P.E.
 

Understand on the model.   I did not know it also compensated for minimal polar misalignment.  Unfortunately, I don't use SGP anymore.  I am a NINA convert after trying just about everything out there, and I am very satisfied.   Going unguided adds another issue.  How do you do coordinated dithering without guiding in NINA?   This is the next challenge since I run an array of three scopes.   I guess for now, given the fact that I do have very stable guiding what I can do is relax my criteria in the PHD2 guiding software so it is doing very little to no corrections and let it act mainly as a coordinated dithering trigger in NINA.  Interested in seeing if anyone else has a better suggestion that would eliminate the guide camera altogether yet still allow me to do coordinated dithering.
 


ap@CaptivePhotons.com
 

On Tue, Jan 25, 2022 at 11:27 AM, Emilio J. Robau, P.E. wrote:
How do you do coordinated dithering without guiding in NINA?   
You can use the "Direct guide" guider under equipment, and NINA will do a dither by slightly moving the mount.


Emilio J. Robau, P.E.
 

Thanks Linwood.  I can set my master to do that trigger, but how about the coordinated portion of the equation? 


 

I believe there's a plug-in for coordinating dithers across multiple scopes in NINA

Dale is on here somewhere ;) he probably has more details or can correct me



On Tue, Jan 25, 2022 at 8:53 AM Emilio J. Robau, P.E. <ejr@...> wrote:
Thanks Linwood.  I can set my master to do that trigger, but how about the coordinated portion of the equation? 



--
Brian 



Brian Valente