Date   

Re: GoTos

fernandorivera3
 

You have loosened the clutches? Don't you mean "tightened down" the clutches?
Try checking your location data in the keypad. Is it accurate or way off like maybe you accidentally left it set on coordinates from a distant star party?
What about the clock time? Is it on standard time rather than daylight savings? Maybe it could be incorrect time zone setting. 

Fernando


Re: Need help connecting APCC to Mach1

Ray Gralak
 

Reinstalling APCC is not likely going to help unless APCC had become corrupted through some disk error on your computer. More likely is that the settings file has become corrupted.

So, try deleting:

C:\ProgramData\Astro-Physics\APCC\settings.apcc

You'll need to reconfigure the connection.

-Ray

-----Original Message-----
From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of Joseph Beyer
Sent: Wednesday, October 13, 2021 11:25 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Need help connecting APCC to Mach1

I posted the message below initially under the topic of "Smart Meridian Flip with NINA" but I'm starting a new
thread on this topic because at this point it has nothing to do with the original problem of a meridian flip. I'm
just trying to get the mount up and running again.

Start of message:

I'm hoping for some suggestions to help restore a functional connection between my computer and the
mount. After the latest event that started with a meridian flip followed by pointing issues which then caused
APCC-Pro to stop responding. I've gone back through all set up instructions for APCC and the V2 driver but
was unable to get the mount to connect correctly. The end result was APCC would only open the then stop
responding and require closing using task manager. The V2 driver would also open but the mount was
unresponsive to both.

This morning George was very helpful in troubleshooting the connection problem. He came to the conclusion
uninstalling and reinstalling APCC-Pro was likely indicated as it appears something may have been corrupted
in the event. I reinstalled APCC and the connection problems were still present. I uninstalled and reinstalled
the V2 driver as well, confirmed all ports were configured correctly in both programs but that also made no
difference.

Currently APCC will open and attempt to connect but the "Connect" window hangs in the middle of the
window. Shortly after that Windows pointing icon turns into a rotating circle and APCC becomes
unresponsive.

I'm stumped at this point.


Need help connecting APCC to Mach1

Joseph Beyer
 

I posted the message below initially under the topic of "Smart Meridian Flip with NINA" but I'm starting a new thread on this topic because at this point it has nothing to do with the original problem of a meridian flip.  I'm just trying to get the mount up and running again. 

Start of message:

I'm hoping for some suggestions to help restore a functional connection between my computer and the mount.  After the latest event that started with a meridian flip followed by pointing issues which then caused APCC-Pro to stop responding.  I've gone back through all set up instructions for APCC and the V2 driver but was unable to get the mount to connect correctly.  The end result was APCC would only open the then stop responding and require closing using task manager.  The V2 driver would also open but the mount was unresponsive to both.


This morning George was very helpful in troubleshooting the connection problem.  He came to the conclusion uninstalling and reinstalling APCC-Pro was likely indicated as it appears something may have been corrupted in the event.  I reinstalled APCC and the connection problems were still present.  I uninstalled and reinstalled the V2 driver as well, confirmed all ports were configured correctly in both programs but that also made no difference.  

Currently APCC will open and attempt to connect but the "Connect" window hangs in the middle of the window.  Shortly after that Windows pointing icon turns into a rotating circle and APCC becomes unresponsive.  

I'm stumped at this point. 


Re: Followup: Re: [ap-gto] Mr. Whang's Mach2 with TOA150

Christopher Erickson
 

What a clear and concise explanation!

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, Oct 13, 2021, 6:54 AM Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
Hello again,

I want to follow up with a bit more information and historical perspective for those interested in how mounts have evolved and why.

Today's mounts are different from previous generation mounts in that today mounts are being used primarily for astrophotography. The precision requirements have increased due to the finer and finer "grain sizes" (pixel sizes) of the detectors compared with the 50 micron grain size of film back in the good ole days.

Originally mounts had their worm gears fixed in place and hard attached to the main axis. This gave the mounts a nice solid feel which was perfect for the visual users that dominated astronomy 20 + years ago. The main problem was slight backlash that was always present because a fixed worm needs a certain amount of clearance to prevent binding. Our legacy mounts, the 400, 600, 800, 900 and 1200 mounts were built this way. Most visual users would simply loosen the clutches a bit and move the scope around manually, so gear backlash was never really noticed. These mounts worked perfectly fine with longish refractors that came in F9 to F12 and beyond focal ratios in sizes from 5 to 10 inches.

Along came CCD cameras and now people want to do astrophotography. At first the 9 micron pixel cameras did not put too much pressure on the precision needed, but eventually smaller pixels come to market and they require more and more precision. So we mount manufacturers develop Periodic Error Compensation to combat worm irregularities. Fixed worms present a problem because of backlash, and that's mainly a problem in Declination where the axis is asked to reverse periodically (RA never reverses so no backlash issue). To combat backlash we introduce spring loaded worms with backstops. The gearbox assemblies now are attached to pivots that gently press the worms into full mesh. This gives the mounts a certain amount of springiness when they are handled in a traditional manner with long heavy refractors, but it produces a vastly superior precise motion in DEC for imaging. The tradeoff then is elimination of backlash and the constant fiddling with worm mesh versus a more springy mount if you push it around manually.

There is also another aspect to the type and geometry of the telescopes that are attached to the mount. In the case of short compound scopes (SCTs, RCs etc) you can weigh the mounts down significantly and not encounter that springiness. There is simply not much moment arm to those short scopes. But lets put a 6" refractor with heavy cameras and field flatteners and auxiliary guide scopes on top of dovetail plates and you may have a 60 - 70 lb setup with a lot of moment arm. How much moment arm a mount can handle depends almost directly on the diameter of the worm wheel. Small diameter worm wheels might be able to carry lots of weight but cannot handle high moment forces. Therefore they will bounce more when disturbed and have longer settling time.

The Mach2 mount has a 6" worm wheel, which means that the teeth are only 3" from the center of the axis shaft. A 60 lb refractor imaging setup with an overall length of 60 inches, weight concentrated at either end, will act as a 10:1 lever on the 6" worm teeth. And it will impart up to 600 lb force on the gear teeth if it is disturbed or suddenly started or stopped. The little spring in the gearbox pivot cannot hold this force and the worm teeth will back out a bit until the backstop is reached. If we use heavier springs to force the worm teeth harder into mesh, then we get more wear during slewing and tracking. We also get more static friction which is the kiss of death for the Dec axis. Static friction causes retrograde motion which causes overshoot and spiking during reversals.

For the RA axis the issue is somewhat worse because the load is doubled at a minimum. So instead of 600lb force on the gear teeth, we have potentially up to 1200 lb with the above setup. That's half a ton that the RA worm teeth are being asked to handle! As long as everything is balanced, there is no problem for the axis to handle the static weight. But we don't want to tighten the clutches and then bang on the end of the scope to see how stable the mount is. Every pound of force is multiplied by 10x.

So, by using spring loaded worms we have much better guiding and less fiddling with worm mesh, but at the cost of mount "feel" or springiness. The Mach2 has mechanical damping internal to the axes, so for normal loads it works quite well. The encoders also help to stiffen the axes when they are active, so under actual use the mount works extremely well for imaging, even when the winds are breezy. The encoders are very effective in keeping the mount pointing to a specific position in the sky when disturbed by an outside force. For example: place a star on a crosshair on your computer screen, video mode, and then hang a 5 lb weight on the end of your scope. The star will scoot across the screen and within a second or so will return right back to the crosshair. Without the encoders the star would have moved off to some other position on the screen and stayed there. Things like cable drag and breezes acting on the telescope are effectively countered by the encoder loop. Without the encoders you only have the guider to bring the star back to the crosshairs, and that is a slow motion thing that is not as responsive as an encoder loop. Encoders sample hundreds of times per second to keep the axis exactly where it is commanded.

I hope the above essay has given some information and perspective and a peek under the hood. I am always happy to answer any questions and clear up any misconceptions you all might have.

Roland Christen
Astro-Physics

-----Original Message-----
From: Roland Christen via groups.io <chris1011=aol.com@groups.io>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Oct 12, 2021 10:11 pm
Subject: [ap-gto] Mr. Whang's Mach2 with TOA150

Hi All,

For those of you on CN, you may have seen this entry by Mr. Whang:

He has a 150TOA with fairly heavy camera and feels that the mount is not stable, even though the package weighs just 55lb. I believe that the weight may not take into consideration the added weight of the dovetail assembly. The tube weight itself is listed at 44lb and if you add the camera and field flattener optics plus the refractor on top, plus the dovetail system, the total weight on the Dec axis is probably more like 60+ lb. The moment arm is pretty large for this combo, so we had to change the damping quite a bit.

Yes, it will feel somewhat boingy when pushed or disturbed, but I have put my own large refractors on the Mach2 and as long as you don't disturb it, the guiding is rock solid down in the 0.2 arc sec when the seeing is good. Right now I have a 12" Mak-Cass on the mount and the Mach2 handles it just fine and guides very well. Wind or no wind. I think Mr. Whang feels that it won't guide with some wind, but remember, the heavier the scope the more it will resist moving (force against mass - mass always wins). I had a 160 EDF refractor with my 10" Mak sitting on top, total weight far in excess of 80lb and yet it guided splendidly even with a good breeze blowing. The scope really didn't move unless I pushed on the end and then of course it bounced around a bit, just like the video that Mr. Whang posted.

Sometimes our feelings about something don't translate into actuality. If I had that 150 TOA setup, I would go ahead and take some actual images and see what the results are.

Rolando

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Re: Smart Meridian Flip with NINA #APCC

Joseph Beyer
 

I'm hoping for some suggestions to help restore a functional connection between my computer and the mount.  After the latest event that started with a meridian flip followed by pointing issues which then caused APCC-Pro to stop responding.  I've gone back through all set up instructions for APCC and the V2 driver but was unable to get the mount to connect correctly.  The end result was APCC would only open the then stop responding and require closing using task manager.  The V2 driver would also open but the mount was unresponsive to both.

This morning George was very helpful in troubleshooting the connection problem.  He came to the conclusion uninstalling and reinstalling APCC-Pro was likely indicated as it appears something may have been corrupted in the event.  I reinstalled APCC and the connection problems were still present.  I uninstalled and reinstalled the V2 driver as well, confirmed all ports were configured correctly in both programs but that also made no difference.  

Currently APCC will open and attempt to connect but the "Connect" window hangs in the middle of the window.  Shortly after that Windows pointing icon turns into a rotating circle and APCC becomes unresponsive.  

I'm stumped at this point. 


Re: GoTos

Howard Hedlund
 

Scroll down this page.    https://www.astro-physics.com/software-updates/


Re: Followup: Re: [ap-gto] Mr. Whang's Mach2 with TOA150

Donald Gaines
 

Hi Roland,

Thanks for the information.  It’s very helpful to users like me to know how something works and why it’s built the way it is.  Thanks so much for taking the time to write this great explanation and history of mounts.

Don Gaines

On Wednesday, October 13, 2021, Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
Hello again,

I want to follow up with a bit more information and historical perspective for those interested in how mounts have evolved and why.

Today's mounts are different from previous generation mounts in that today mounts are being used primarily for astrophotography. The precision requirements have increased due to the finer and finer "grain sizes" (pixel sizes) of the detectors compared with the 50 micron grain size of film back in the good ole days.

Originally mounts had their worm gears fixed in place and hard attached to the main axis. This gave the mounts a nice solid feel which was perfect for the visual users that dominated astronomy 20 + years ago. The main problem was slight backlash that was always present because a fixed worm needs a certain amount of clearance to prevent binding. Our legacy mounts, the 400, 600, 800, 900 and 1200 mounts were built this way. Most visual users would simply loosen the clutches a bit and move the scope around manually, so gear backlash was never really noticed. These mounts worked perfectly fine with longish refractors that came in F9 to F12 and beyond focal ratios in sizes from 5 to 10 inches.

Along came CCD cameras and now people want to do astrophotography. At first the 9 micron pixel cameras did not put too much pressure on the precision needed, but eventually smaller pixels come to market and they require more and more precision. So we mount manufacturers develop Periodic Error Compensation to combat worm irregularities. Fixed worms present a problem because of backlash, and that's mainly a problem in Declination where the axis is asked to reverse periodically (RA never reverses so no backlash issue). To combat backlash we introduce spring loaded worms with backstops. The gearbox assemblies now are attached to pivots that gently press the worms into full mesh. This gives the mounts a certain amount of springiness when they are handled in a traditional manner with long heavy refractors, but it produces a vastly superior precise motion in DEC for imaging. The tradeoff then is elimination of backlash and the constant fiddling with worm mesh versus a more springy mount if you push it around manually.

There is also another aspect to the type and geometry of the telescopes that are attached to the mount. In the case of short compound scopes (SCTs, RCs etc) you can weigh the mounts down significantly and not encounter that springiness. There is simply not much moment arm to those short scopes. But lets put a 6" refractor with heavy cameras and field flatteners and auxiliary guide scopes on top of dovetail plates and you may have a 60 - 70 lb setup with a lot of moment arm. How much moment arm a mount can handle depends almost directly on the diameter of the worm wheel. Small diameter worm wheels might be able to carry lots of weight but cannot handle high moment forces. Therefore they will bounce more when disturbed and have longer settling time.

The Mach2 mount has a 6" worm wheel, which means that the teeth are only 3" from the center of the axis shaft. A 60 lb refractor imaging setup with an overall length of 60 inches, weight concentrated at either end, will act as a 10:1 lever on the 6" worm teeth. And it will impart up to 600 lb force on the gear teeth if it is disturbed or suddenly started or stopped. The little spring in the gearbox pivot cannot hold this force and the worm teeth will back out a bit until the backstop is reached. If we use heavier springs to force the worm teeth harder into mesh, then we get more wear during slewing and tracking. We also get more static friction which is the kiss of death for the Dec axis. Static friction causes retrograde motion which causes overshoot and spiking during reversals.

For the RA axis the issue is somewhat worse because the load is doubled at a minimum. So instead of 600lb force on the gear teeth, we have potentially up to 1200 lb with the above setup. That's half a ton that the RA worm teeth are being asked to handle! As long as everything is balanced, there is no problem for the axis to handle the static weight. But we don't want to tighten the clutches and then bang on the end of the scope to see how stable the mount is. Every pound of force is multiplied by 10x.

So, by using spring loaded worms we have much better guiding and less fiddling with worm mesh, but at the cost of mount "feel" or springiness. The Mach2 has mechanical damping internal to the axes, so for normal loads it works quite well. The encoders also help to stiffen the axes when they are active, so under actual use the mount works extremely well for imaging, even when the winds are breezy. The encoders are very effective in keeping the mount pointing to a specific position in the sky when disturbed by an outside force. For example: place a star on a crosshair on your computer screen, video mode, and then hang a 5 lb weight on the end of your scope. The star will scoot across the screen and within a second or so will return right back to the crosshair. Without the encoders the star would have moved off to some other position on the screen and stayed there. Things like cable drag and breezes acting on the telescope are effectively countered by the encoder loop. Without the encoders you only have the guider to bring the star back to the crosshairs, and that is a slow motion thing that is not as responsive as an encoder loop. Encoders sample hundreds of times per second to keep the axis exactly where it is commanded.

I hope the above essay has given some information and perspective and a peek under the hood. I am always happy to answer any questions and clear up any misconceptions you all might have.

Roland Christen
Astro-Physics

-----Original Message-----
From: Roland Christen via groups.io <chris1011=aol.com@groups.io>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Oct 12, 2021 10:11 pm
Subject: [ap-gto] Mr. Whang's Mach2 with TOA150

Hi All,

For those of you on CN, you may have seen this entry by Mr. Whang:

He has a 150TOA with fairly heavy camera and feels that the mount is not stable, even though the package weighs just 55lb. I believe that the weight may not take into consideration the added weight of the dovetail assembly. The tube weight itself is listed at 44lb and if you add the camera and field flattener optics plus the refractor on top, plus the dovetail system, the total weight on the Dec axis is probably more like 60+ lb. The moment arm is pretty large for this combo, so we had to change the damping quite a bit.

Yes, it will feel somewhat boingy when pushed or disturbed, but I have put my own large refractors on the Mach2 and as long as you don't disturb it, the guiding is rock solid down in the 0.2 arc sec when the seeing is good. Right now I have a 12" Mak-Cass on the mount and the Mach2 handles it just fine and guides very well. Wind or no wind. I think Mr. Whang feels that it won't guide with some wind, but remember, the heavier the scope the more it will resist moving (force against mass - mass always wins). I had a 160 EDF refractor with my 10" Mak sitting on top, total weight far in excess of 80lb and yet it guided splendidly even with a good breeze blowing. The scope really didn't move unless I pushed on the end and then of course it bounced around a bit, just like the video that Mr. Whang posted.

Sometimes our feelings about something don't translate into actuality. If I had that 150 TOA setup, I would go ahead and take some actual images and see what the results are.

Rolando

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Re: Followup: Re: [ap-gto] Mr. Whang's Mach2 with TOA150

Kenneth Tan
 

Thx for the highly educational discourse! 

Kenneth

On Thu, 14 Oct 2021 at 00:54, Roland Christen via groups.io <chris1011=aol.com@groups.io> wrote:
Hello again,

I want to follow up with a bit more information and historical perspective for those interested in how mounts have evolved and why.

Today's mounts are different from previous generation mounts in that today mounts are being used primarily for astrophotography. The precision requirements have increased due to the finer and finer "grain sizes" (pixel sizes) of the detectors compared with the 50 micron grain size of film back in the good ole days.

Originally mounts had their worm gears fixed in place and hard attached to the main axis. This gave the mounts a nice solid feel which was perfect for the visual users that dominated astronomy 20 + years ago. The main problem was slight backlash that was always present because a fixed worm needs a certain amount of clearance to prevent binding. Our legacy mounts, the 400, 600, 800, 900 and 1200 mounts were built this way. Most visual users would simply loosen the clutches a bit and move the scope around manually, so gear backlash was never really noticed. These mounts worked perfectly fine with longish refractors that came in F9 to F12 and beyond focal ratios in sizes from 5 to 10 inches.

Along came CCD cameras and now people want to do astrophotography. At first the 9 micron pixel cameras did not put too much pressure on the precision needed, but eventually smaller pixels come to market and they require more and more precision. So we mount manufacturers develop Periodic Error Compensation to combat worm irregularities. Fixed worms present a problem because of backlash, and that's mainly a problem in Declination where the axis is asked to reverse periodically (RA never reverses so no backlash issue). To combat backlash we introduce spring loaded worms with backstops. The gearbox assemblies now are attached to pivots that gently press the worms into full mesh. This gives the mounts a certain amount of springiness when they are handled in a traditional manner with long heavy refractors, but it produces a vastly superior precise motion in DEC for imaging. The tradeoff then is elimination of backlash and the constant fiddling with worm mesh versus a more springy mount if you push it around manually.

There is also another aspect to the type and geometry of the telescopes that are attached to the mount. In the case of short compound scopes (SCTs, RCs etc) you can weigh the mounts down significantly and not encounter that springiness. There is simply not much moment arm to those short scopes. But lets put a 6" refractor with heavy cameras and field flatteners and auxiliary guide scopes on top of dovetail plates and you may have a 60 - 70 lb setup with a lot of moment arm. How much moment arm a mount can handle depends almost directly on the diameter of the worm wheel. Small diameter worm wheels might be able to carry lots of weight but cannot handle high moment forces. Therefore they will bounce more when disturbed and have longer settling time.

The Mach2 mount has a 6" worm wheel, which means that the teeth are only 3" from the center of the axis shaft. A 60 lb refractor imaging setup with an overall length of 60 inches, weight concentrated at either end, will act as a 10:1 lever on the 6" worm teeth. And it will impart up to 600 lb force on the gear teeth if it is disturbed or suddenly started or stopped. The little spring in the gearbox pivot cannot hold this force and the worm teeth will back out a bit until the backstop is reached. If we use heavier springs to force the worm teeth harder into mesh, then we get more wear during slewing and tracking. We also get more static friction which is the kiss of death for the Dec axis. Static friction causes retrograde motion which causes overshoot and spiking during reversals.

For the RA axis the issue is somewhat worse because the load is doubled at a minimum. So instead of 600lb force on the gear teeth, we have potentially up to 1200 lb with the above setup. That's half a ton that the RA worm teeth are being asked to handle! As long as everything is balanced, there is no problem for the axis to handle the static weight. But we don't want to tighten the clutches and then bang on the end of the scope to see how stable the mount is. Every pound of force is multiplied by 10x.

So, by using spring loaded worms we have much better guiding and less fiddling with worm mesh, but at the cost of mount "feel" or springiness. The Mach2 has mechanical damping internal to the axes, so for normal loads it works quite well. The encoders also help to stiffen the axes when they are active, so under actual use the mount works extremely well for imaging, even when the winds are breezy. The encoders are very effective in keeping the mount pointing to a specific position in the sky when disturbed by an outside force. For example: place a star on a crosshair on your computer screen, video mode, and then hang a 5 lb weight on the end of your scope. The star will scoot across the screen and within a second or so will return right back to the crosshair. Without the encoders the star would have moved off to some other position on the screen and stayed there. Things like cable drag and breezes acting on the telescope are effectively countered by the encoder loop. Without the encoders you only have the guider to bring the star back to the crosshairs, and that is a slow motion thing that is not as responsive as an encoder loop. Encoders sample hundreds of times per second to keep the axis exactly where it is commanded.

I hope the above essay has given some information and perspective and a peek under the hood. I am always happy to answer any questions and clear up any misconceptions you all might have.

Roland Christen
Astro-Physics

-----Original Message-----
From: Roland Christen via groups.io <chris1011=aol.com@groups.io>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Oct 12, 2021 10:11 pm
Subject: [ap-gto] Mr. Whang's Mach2 with TOA150

Hi All,

For those of you on CN, you may have seen this entry by Mr. Whang:

He has a 150TOA with fairly heavy camera and feels that the mount is not stable, even though the package weighs just 55lb. I believe that the weight may not take into consideration the added weight of the dovetail assembly. The tube weight itself is listed at 44lb and if you add the camera and field flattener optics plus the refractor on top, plus the dovetail system, the total weight on the Dec axis is probably more like 60+ lb. The moment arm is pretty large for this combo, so we had to change the damping quite a bit.

Yes, it will feel somewhat boingy when pushed or disturbed, but I have put my own large refractors on the Mach2 and as long as you don't disturb it, the guiding is rock solid down in the 0.2 arc sec when the seeing is good. Right now I have a 12" Mak-Cass on the mount and the Mach2 handles it just fine and guides very well. Wind or no wind. I think Mr. Whang feels that it won't guide with some wind, but remember, the heavier the scope the more it will resist moving (force against mass - mass always wins). I had a 160 EDF refractor with my 10" Mak sitting on top, total weight far in excess of 80lb and yet it guided splendidly even with a good breeze blowing. The scope really didn't move unless I pushed on the end and then of course it bounced around a bit, just like the video that Mr. Whang posted.

Sometimes our feelings about something don't translate into actuality. If I had that 150 TOA setup, I would go ahead and take some actual images and see what the results are.

Rolando


--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Re: Followup: Re: [ap-gto] Mr. Whang's Mach2 with TOA150

Cheng-Yang Tan
 

Hi Rolando,
  I've read WHWang's travails with the 150 on cloudynights. From your description below, isn't it obvious that he is under-mounted with the Mach2? The little engine that could is being forced into a situation that is probably outside the Mach2 specs under windy conditions. I would assume that mounting his 150 on a AP1100AE would solve his problems.

cytan

On Wednesday, October 13, 2021, 11:54:20 AM CDT, Roland Christen via groups.io <chris1011@...> wrote:


Hello again,

I want to follow up with a bit more information and historical perspective for those interested in how mounts have evolved and why.

Today's mounts are different from previous generation mounts in that today mounts are being used primarily for astrophotography. The precision requirements have increased due to the finer and finer "grain sizes" (pixel sizes) of the detectors compared with the 50 micron grain size of film back in the good ole days.

Originally mounts had their worm gears fixed in place and hard attached to the main axis. This gave the mounts a nice solid feel which was perfect for the visual users that dominated astronomy 20 + years ago. The main problem was slight backlash that was always present because a fixed worm needs a certain amount of clearance to prevent binding. Our legacy mounts, the 400, 600, 800, 900 and 1200 mounts were built this way. Most visual users would simply loosen the clutches a bit and move the scope around manually, so gear backlash was never really noticed. These mounts worked perfectly fine with longish refractors that came in F9 to F12 and beyond focal ratios in sizes from 5 to 10 inches.

Along came CCD cameras and now people want to do astrophotography. At first the 9 micron pixel cameras did not put too much pressure on the precision needed, but eventually smaller pixels come to market and they require more and more precision. So we mount manufacturers develop Periodic Error Compensation to combat worm irregularities. Fixed worms present a problem because of backlash, and that's mainly a problem in Declination where the axis is asked to reverse periodically (RA never reverses so no backlash issue). To combat backlash we introduce spring loaded worms with backstops. The gearbox assemblies now are attached to pivots that gently press the worms into full mesh. This gives the mounts a certain amount of springiness when they are handled in a traditional manner with long heavy refractors, but it produces a vastly superior precise motion in DEC for imaging. The tradeoff then is elimination of backlash and the constant fiddling with worm mesh versus a more springy mount if you push it around manually.

There is also another aspect to the type and geometry of the telescopes that are attached to the mount. In the case of short compound scopes (SCTs, RCs etc) you can weigh the mounts down significantly and not encounter that springiness. There is simply not much moment arm to those short scopes. But lets put a 6" refractor with heavy cameras and field flatteners and auxiliary guide scopes on top of dovetail plates and you may have a 60 - 70 lb setup with a lot of moment arm. How much moment arm a mount can handle depends almost directly on the diameter of the worm wheel. Small diameter worm wheels might be able to carry lots of weight but cannot handle high moment forces. Therefore they will bounce more when disturbed and have longer settling time.

The Mach2 mount has a 6" worm wheel, which means that the teeth are only 3" from the center of the axis shaft. A 60 lb refractor imaging setup with an overall length of 60 inches, weight concentrated at either end, will act as a 10:1 lever on the 6" worm teeth. And it will impart up to 600 lb force on the gear teeth if it is disturbed or suddenly started or stopped. The little spring in the gearbox pivot cannot hold this force and the worm teeth will back out a bit until the backstop is reached. If we use heavier springs to force the worm teeth harder into mesh, then we get more wear during slewing and tracking. We also get more static friction which is the kiss of death for the Dec axis. Static friction causes retrograde motion which causes overshoot and spiking during reversals.

For the RA axis the issue is somewhat worse because the load is doubled at a minimum. So instead of 600lb force on the gear teeth, we have potentially up to 1200 lb with the above setup. That's half a ton that the RA worm teeth are being asked to handle! As long as everything is balanced, there is no problem for the axis to handle the static weight. But we don't want to tighten the clutches and then bang on the end of the scope to see how stable the mount is. Every pound of force is multiplied by 10x.

So, by using spring loaded worms we have much better guiding and less fiddling with worm mesh, but at the cost of mount "feel" or springiness. The Mach2 has mechanical damping internal to the axes, so for normal loads it works quite well. The encoders also help to stiffen the axes when they are active, so under actual use the mount works extremely well for imaging, even when the winds are breezy. The encoders are very effective in keeping the mount pointing to a specific position in the sky when disturbed by an outside force. For example: place a star on a crosshair on your computer screen, video mode, and then hang a 5 lb weight on the end of your scope. The star will scoot across the screen and within a second or so will return right back to the crosshair. Without the encoders the star would have moved off to some other position on the screen and stayed there. Things like cable drag and breezes acting on the telescope are effectively countered by the encoder loop. Without the encoders you only have the guider to bring the star back to the crosshairs, and that is a slow motion thing that is not as responsive as an encoder loop. Encoders sample hundreds of times per second to keep the axis exactly where it is commanded.

I hope the above essay has given some information and perspective and a peek under the hood. I am always happy to answer any questions and clear up any misconceptions you all might have.

Roland Christen
Astro-Physics

-----Original Message-----
From: Roland Christen via groups.io <chris1011@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Oct 12, 2021 10:11 pm
Subject: [ap-gto] Mr. Whang's Mach2 with TOA150

Hi All,

For those of you on CN, you may have seen this entry by Mr. Whang:
https://www.cloudynights.com/topic/767964-lets-torture-the-mach-2/page-6#entry11425336

He has a 150TOA with fairly heavy camera and feels that the mount is not stable, even though the package weighs just 55lb. I believe that the weight may not take into consideration the added weight of the dovetail assembly. The tube weight itself is listed at 44lb and if you add the camera and field flattener optics plus the refractor on top, plus the dovetail system, the total weight on the Dec axis is probably more like 60+ lb. The moment arm is pretty large for this combo, so we had to change the damping quite a bit.

Yes, it will feel somewhat boingy when pushed or disturbed, but I have put my own large refractors on the Mach2 and as long as you don't disturb it, the guiding is rock solid down in the 0.2 arc sec when the seeing is good. Right now I have a 12" Mak-Cass on the mount and the Mach2 handles it just fine and guides very well. Wind or no wind. I think Mr. Whang feels that it won't guide with some wind, but remember, the heavier the scope the more it will resist moving (force against mass - mass always wins). I had a 160 EDF refractor with my 10" Mak sitting on top, total weight far in excess of 80lb and yet it guided splendidly even with a good breeze blowing. The scope really didn't move unless I pushed on the end and then of course it bounced around a bit, just like the video that Mr. Whang posted.

Sometimes our feelings about something don't translate into actuality. If I had that 150 TOA setup, I would go ahead and take some actual images and see what the results are.

Rolando

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Followup: Re: [ap-gto] Mr. Whang's Mach2 with TOA150

Roland Christen
 

Hello again,

I want to follow up with a bit more information and historical perspective for those interested in how mounts have evolved and why.

Today's mounts are different from previous generation mounts in that today mounts are being used primarily for astrophotography. The precision requirements have increased due to the finer and finer "grain sizes" (pixel sizes) of the detectors compared with the 50 micron grain size of film back in the good ole days.

Originally mounts had their worm gears fixed in place and hard attached to the main axis. This gave the mounts a nice solid feel which was perfect for the visual users that dominated astronomy 20 + years ago. The main problem was slight backlash that was always present because a fixed worm needs a certain amount of clearance to prevent binding. Our legacy mounts, the 400, 600, 800, 900 and 1200 mounts were built this way. Most visual users would simply loosen the clutches a bit and move the scope around manually, so gear backlash was never really noticed. These mounts worked perfectly fine with longish refractors that came in F9 to F12 and beyond focal ratios in sizes from 5 to 10 inches.

Along came CCD cameras and now people want to do astrophotography. At first the 9 micron pixel cameras did not put too much pressure on the precision needed, but eventually smaller pixels come to market and they require more and more precision. So we mount manufacturers develop Periodic Error Compensation to combat worm irregularities. Fixed worms present a problem because of backlash, and that's mainly a problem in Declination where the axis is asked to reverse periodically (RA never reverses so no backlash issue). To combat backlash we introduce spring loaded worms with backstops. The gearbox assemblies now are attached to pivots that gently press the worms into full mesh. This gives the mounts a certain amount of springiness when they are handled in a traditional manner with long heavy refractors, but it produces a vastly superior precise motion in DEC for imaging. The tradeoff then is elimination of backlash and the constant fiddling with worm mesh versus a more springy mount if you push it around manually.

There is also another aspect to the type and geometry of the telescopes that are attached to the mount. In the case of short compound scopes (SCTs, RCs etc) you can weigh the mounts down significantly and not encounter that springiness. There is simply not much moment arm to those short scopes. But lets put a 6" refractor with heavy cameras and field flatteners and auxiliary guide scopes on top of dovetail plates and you may have a 60 - 70 lb setup with a lot of moment arm. How much moment arm a mount can handle depends almost directly on the diameter of the worm wheel. Small diameter worm wheels might be able to carry lots of weight but cannot handle high moment forces. Therefore they will bounce more when disturbed and have longer settling time.

The Mach2 mount has a 6" worm wheel, which means that the teeth are only 3" from the center of the axis shaft. A 60 lb refractor imaging setup with an overall length of 60 inches, weight concentrated at either end, will act as a 10:1 lever on the 6" worm teeth. And it will impart up to 600 lb force on the gear teeth if it is disturbed or suddenly started or stopped. The little spring in the gearbox pivot cannot hold this force and the worm teeth will back out a bit until the backstop is reached. If we use heavier springs to force the worm teeth harder into mesh, then we get more wear during slewing and tracking. We also get more static friction which is the kiss of death for the Dec axis. Static friction causes retrograde motion which causes overshoot and spiking during reversals.

For the RA axis the issue is somewhat worse because the load is doubled at a minimum. So instead of 600lb force on the gear teeth, we have potentially up to 1200 lb with the above setup. That's half a ton that the RA worm teeth are being asked to handle! As long as everything is balanced, there is no problem for the axis to handle the static weight. But we don't want to tighten the clutches and then bang on the end of the scope to see how stable the mount is. Every pound of force is multiplied by 10x.

So, by using spring loaded worms we have much better guiding and less fiddling with worm mesh, but at the cost of mount "feel" or springiness. The Mach2 has mechanical damping internal to the axes, so for normal loads it works quite well. The encoders also help to stiffen the axes when they are active, so under actual use the mount works extremely well for imaging, even when the winds are breezy. The encoders are very effective in keeping the mount pointing to a specific position in the sky when disturbed by an outside force. For example: place a star on a crosshair on your computer screen, video mode, and then hang a 5 lb weight on the end of your scope. The star will scoot across the screen and within a second or so will return right back to the crosshair. Without the encoders the star would have moved off to some other position on the screen and stayed there. Things like cable drag and breezes acting on the telescope are effectively countered by the encoder loop. Without the encoders you only have the guider to bring the star back to the crosshairs, and that is a slow motion thing that is not as responsive as an encoder loop. Encoders sample hundreds of times per second to keep the axis exactly where it is commanded.

I hope the above essay has given some information and perspective and a peek under the hood. I am always happy to answer any questions and clear up any misconceptions you all might have.

Roland Christen
Astro-Physics

-----Original Message-----
From: Roland Christen via groups.io <chris1011@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Oct 12, 2021 10:11 pm
Subject: [ap-gto] Mr. Whang's Mach2 with TOA150

Hi All,

For those of you on CN, you may have seen this entry by Mr. Whang:
https://www.cloudynights.com/topic/767964-lets-torture-the-mach-2/page-6#entry11425336

He has a 150TOA with fairly heavy camera and feels that the mount is not stable, even though the package weighs just 55lb. I believe that the weight may not take into consideration the added weight of the dovetail assembly. The tube weight itself is listed at 44lb and if you add the camera and field flattener optics plus the refractor on top, plus the dovetail system, the total weight on the Dec axis is probably more like 60+ lb. The moment arm is pretty large for this combo, so we had to change the damping quite a bit.

Yes, it will feel somewhat boingy when pushed or disturbed, but I have put my own large refractors on the Mach2 and as long as you don't disturb it, the guiding is rock solid down in the 0.2 arc sec when the seeing is good. Right now I have a 12" Mak-Cass on the mount and the Mach2 handles it just fine and guides very well. Wind or no wind. I think Mr. Whang feels that it won't guide with some wind, but remember, the heavier the scope the more it will resist moving (force against mass - mass always wins). I had a 160 EDF refractor with my 10" Mak sitting on top, total weight far in excess of 80lb and yet it guided splendidly even with a good breeze blowing. The scope really didn't move unless I pushed on the end and then of course it bounced around a bit, just like the video that Mr. Whang posted.

Sometimes our feelings about something don't translate into actuality. If I had that 150 TOA setup, I would go ahead and take some actual images and see what the results are.

Rolando

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


Re: GoTos

Mike Dodd
 

On 10/13/2021 12:27 PM, Christopher Erickson wrote:
Time to re-upload fresh code to the hand controller.
And to answer your "how hard" question, it's easy and straightforward. Download the database file from A-P, and follow the instructions in a document named dataload201.pdf. I don't know where to find it on the website, so maybe A-P can chime in.

--- mike


Re: GoTos

Michael Hamburg
 

Hi Christopher,
That's quite a list of culprits. Slight chance it could be #s 4 and 8. Definitely #11 is playing a big part. Pier goes down 9 feet and is filled with a lot of concrete.

Best wishes, Michael


On Wednesday, October 13, 2021, 12:22:57 PM EDT, Michael Hamburg via groups.io <michael_hamburg44@...> wrote:


PA is very good as evidenced by small corrections via PHD2.

Best wishes, Michael


On Wednesday, October 13, 2021, 12:11:20 PM EDT, Howard Hedlund <howard@...> wrote:


Keypad database corruption is generally catastrophic in terms of GoTos.  Database corruption sends you to the complete wrong place - not just *off-by-a-bit*.  And that's if you can slew to catalog objects at all.  

The number one reason by a HUGE margin for poor pointing is poor polar alignment.


Re: GoTos

Christopher Erickson
 

If the hand controller battery was replaced at some point then it is almost a certainty that the object database in the hand controller was corrupted by the bad battery, or got corrupted when the battery was replaced. Time to re-upload fresh code to the hand controller.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   

On Wed, Oct 13, 2021, 6:22 AM Michael Hamburg via groups.io <michael_hamburg44=yahoo.com@groups.io> wrote:
PA is very good as evidenced by small corrections via PHD2.

Best wishes, Michael


On Wednesday, October 13, 2021, 12:11:20 PM EDT, Howard Hedlund <howard@...> wrote:


Keypad database corruption is generally catastrophic in terms of GoTos.  Database corruption sends you to the complete wrong place - not just *off-by-a-bit*.  And that's if you can slew to catalog objects at all.  

The number one reason by a HUGE margin for poor pointing is poor polar alignment.


Re: GoTos

Michael Hamburg
 

PA is very good as evidenced by small corrections via PHD2.

Best wishes, Michael


On Wednesday, October 13, 2021, 12:11:20 PM EDT, Howard Hedlund <howard@...> wrote:


Keypad database corruption is generally catastrophic in terms of GoTos.  Database corruption sends you to the complete wrong place - not just *off-by-a-bit*.  And that's if you can slew to catalog objects at all.  

The number one reason by a HUGE margin for poor pointing is poor polar alignment.


Re: GoTos

Christopher Erickson
 

To me, some of the possibilities are:

1. Orthogonality/Cone-error.
2. Corrupted hand controller.
3. Misconfigured hand controller.
4. OTA/attachment mech problem.
5. Motor optical encoder problem.
6. Usage procedure problem.
7. Polar alignment problem.
8. Debris between 2 halves of mount.
9. Tripod/pier flexure/looseness.
10. Soft ground.
11. Astro-gremlins.

On Wed, Oct 13, 2021, 5:56 AM Scott Cooke <TSCOOKE64@...> wrote:
Exactly. Unless you already did, it would be worth replacing the keypad battery and updating the DB of objects. 

Scott Cooke



On Oct 13, 2021, at 10:37 AM, M Hambrick <mhambrick563@...> wrote:

Is the object database in your keypad corrupted ? You might want to cross check the coordinates that you get from the keypad with the published coordinates.

Mike


-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738
www.summitkinetics.com
   


Re: RA Mesh adjustment for 2104 model Mach 1 GTO

Bill Long
 

The shift key on a desktop keyboard and the shift key on a laptop keyboard will do the same thing.

Like Roland, I do a fresh calibration every time I use the mount, even if it has been left outside and nothing has changed at all. I guess I can say I kind of cheat on that, as my automation does the PHD calibration for me every time the Voyager DragScript is run -- but the net effect is the same. I also check and tweak my Polar Alignment each night (before the calibration of course) but that just gives me something to do when I am waiting for the sky to darken up. 

Another very important thing to know about PHD2:  If you manually rotate the camera after you calibrate PHD2 you need to calibrate it again. If you have an automated ASCOM rotator hooked up to PHD, I believe it can still use the previous calibration (since it knows about the rotation) but I have never relied on that feature, and I always recalibrate PHD even if it was my NiteCrawler that did the rotation for me.


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of nicholas via groups.io <chironik@...>
Sent: Tuesday, October 12, 2021 7:36 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] RA Mesh adjustment for 2104 model Mach 1 GTO
 
I really appreciate the feedback. the entire community is enriched by your participation. 

That being said I do need to clarify something on this thread. As I have looked back at my guide screen, I was not only checking off " auto-restore."   I was  also  checking  "clear mount calibration."  In fact I think in my case auto-restore is always checked and before I begin guiding I check "clear mount calibration." I am quite sure I did so the other night. If this is  a way to calibrate, and I believe  it is, it seems more gratifying because from my perspective I can confirm the operation/command has been initiated. The shift click method, well, I just want to make sure it happens and the intended command is sent to Phd2 .  I have noticed with Windows laptops the functions are different from what they are on desktop keyboards. At least for keystrokes involving function keys.  Actually I am looking at my laptop, it has no function keys, just a top row of number keys. Likely this  has no affect with this shift click operation. But I am looking for the surfeit way to get the command to Phd2. And again I  am looking at my guide screen and auto restore calibration is checked off as a sort of default in my settings atleast. 


Re: GoTos

Howard Hedlund
 

Keypad database corruption is generally catastrophic in terms of GoTos.  Database corruption sends you to the complete wrong place - not just *off-by-a-bit*.  And that's if you can slew to catalog objects at all.  

The number one reason by a HUGE margin for poor pointing is poor polar alignment.


Re: GoTos

Michael Hamburg
 

Thanks for the suggestions. I replaced the battery soon after I got the mount. The comparing the coordinates sounds like a good first step. How complicated is it to replace the database if necessary?
Michael


Best wishes, Michael


On Wednesday, October 13, 2021, 11:56:19 AM EDT, Scott Cooke <tscooke64@...> wrote:


Exactly. Unless you already did, it would be worth replacing the keypad battery and updating the DB of objects. 

Scott Cooke



On Oct 13, 2021, at 10:37 AM, M Hambrick <mhambrick563@...> wrote:

Is the object database in your keypad corrupted ? You might want to cross check the coordinates that you get from the keypad with the published coordinates.

Mike


Re: GoTos

Scott Cooke
 

Exactly. Unless you already did, it would be worth replacing the keypad battery and updating the DB of objects. 

Scott Cooke



On Oct 13, 2021, at 10:37 AM, M Hambrick <mhambrick563@...> wrote:

Is the object database in your keypad corrupted ? You might want to cross check the coordinates that you get from the keypad with the published coordinates.

Mike


Re: GoTos

Roland Christen
 

Could be anything, depends also on how far you are off. Without more specifics, we are shooting in the wind.

Rolando

-----Original Message-----
From: Michael Hamburg via groups.io <michael_hamburg44@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Wed, Oct 13, 2021 9:16 am
Subject: [ap-gto] GoTos

I truly love my AP900 GTO3 which I bought from the original owner a couple of years ago. However, I cannot get accurate GoTos no matter what I try. I use solely the had controller with the upgraded chip. I have synched, recalibrated, loosened  the clutches, issued GoTo commands, and retightened the clutches. I currently carry a Celestron Edge 11 HD with an Orion 80mm ED refractor piggybacked. The mount easily carries this set-up. So - is it 1) user error? 2) cone error (orthogonality?) 3) software bug? or 4) a nasty gremlin? Please help!

Michael HamburgEmoji

--
Roland Christen
Astro-Physics

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