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CEM60 vibration

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#51 Real14

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Posted 19 February 2018 - 08:05 PM

 

Hi,

 

 

 

From yoru point of view a non clamping clamp can be the cause for vibrations. OK the clamp can wear out, no doubts about it but before that steel clamp shows a sign of wear out, the first thing showing a wear would be the surface on which it is pressing as that part is a foundry piece and that could be a 100% Aluminum body or perhaps even a Magnesium/Aluminum alloy and those foundry parts are always softer than Steel.

 

Now in order to check if the clamp does not do its job anymore get a thin strip of aluminum of a can, maybe 2mm wide and a few centimeters long. Bend it straight and push it into the space between the front part of the clamp and the non movable support for the head assembly (green arrow). If you can stick it through with ease then the clamp is doing its job. Of course,first take it off and clean that part well. 

 

Now let us assume the clamp is not clamping. What could that mean that the head is not held sideways on the lower support, but in order that the movable part on the lower fixed support vibrates would mean you really need a continuous sideways movement in order to lift it up on one side and then on the other. From where would that force come ? unless you push it with your fingers ... the stepper motors stepping with I do not know how many few steps per minute. How can the rotor of a stepper motor cause so much vibration in order to mothe whole enchilada on his seating ?

 

The case that having on the head assembly eg. 50 pounds of gear makes it impossible for the whole enchilada to dance from side to side.

 

Image taken from dvalid post # 43

 

 

attachicon.gif cem60clamp.jpg

 

'Now in order to check if the clamp does not do its job anymore get a thin strip of aluminum of a can, maybe 2mm wide and a few centimeters long. Bend it straight and push it into the space between the front part of the clamp and the non movable support for the head assembly (green arrow). If you can stick it through with ease then the clamp is doing its job. Of course,first take it off and clean that part well.'

 

That's what I did some time ago. It feels more rigid, didn't test with the actual load yet though.

 

https://www.cloudyni...nent/?p=8328737

 

'Now let us assume the clamp is not clamping. What could that mean that the head is not held sideways on the lower support, but in order that the movable part on the lower fixed support vibrates would mean you really need a continuous sideways movement in order to lift it up on one side and then on the other. From where would that force come ? unless you push it with your fingers ... the stepper motors stepping with I do not know how many few steps per minute. How can the rotor of a stepper motor cause so much vibration in order to mothe whole enchilada on his seating ? The case that having on the head assembly eg. 50 pounds of gear makes it impossible for the whole enchilada to dance from side to side'.

 

Rainer, I did not get this point, are you questioning existence of the vibration phenomena  in general? 

 

David

 

Hi David,

 

 

Rainer, I did not get this point, are you questioning existence of the vibration phenomena  in general?

You are putting letters on my keyboard.

 

No, not at all. Vibrations can have many sources and that has been discussed to death by another members here and in many other threads.

 

I am just questioning how can stepper motors moving at minimal revolutions per minute and having very small rotors induce such a heavy weight to vibrate ... There must be an outside force which induces to vibrations. 


Edited by Jaimo!, 19 February 2018 - 08:34 PM.


#52 Waldemar

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Posted 20 February 2018 - 02:08 AM

" I am just questioning how can stepper motors moving at minimal revolutions per minute and having very small rotors induce such a heavy weight to vibrate ... There must be an outside force which induces to vibrations." 

 

The same force that is able to move that weight, is able to cause vibrations, because of the gear ratio, which is the determining factor for the introduced force, not just the tiny rotors.

I agree some other outside constructional factors may have quite a big influence as well, like a rat cage construction or a too weak pier, which may boost the effect by vibrational resonance, but I do believe this has all been checked and found not applicable. 


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#53 cloudywest

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Posted 20 February 2018 - 02:19 AM

There were in depth of discussion in another thread posted by the same owner and plenty of replies pointed out most likely the vibration was due to improper pier/tripod setup; long bolts formed a "rat cage", and apple on a straw (6" minipier on top of a skinny 4" pier).



#54 adastranova

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Posted 20 February 2018 - 05:22 AM

There were in depth of discussion in another thread posted by the same owner and plenty of replies pointed out most likely the vibration was due to improper pier/tripod setup; long bolts formed a "rat cage", and apple on a straw (6" minipier on top of a skinny 4" pier).

Performance on tripod was same as on pier, as stated above. Could they both be bad in an identical way? Also vibrations were not just subtle, affecting astro-images. You could see the whole OTA body shaking, like a tuning fork. And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece. My tripod was used with a number of setups over the years, including much heavier ones, and never showed anything like this. You would need to see the shaking to appreciate the magnitude. This is not just a matter of waiting for vibrations to dampen, but never being in control of when they would start.



#55 gotak

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Posted 20 February 2018 - 06:50 AM


There were in depth of discussion in another thread posted by the same owner and plenty of replies pointed out most likely the vibration was due to improper pier/tripod setup; long bolts formed a "rat cage", and apple on a straw (6" minipier on top of a skinny 4" pier).

Performance on tripod was same as on pier, as stated above. Could they both be bad in an identical way? Also vibrations were not just subtle, affecting astro-images. You could see the whole OTA body shaking, like a tuning fork. And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece. My tripod was used with a number of setups over the years, including much heavier ones, and never showed anything like this. You would need to see the shaking to appreciate the magnitude. This is not just a matter of waiting for vibrations to dampen, but never being in control of when they would start.
The Tacoma narrows bridge is way heavier than any scope setup you had and worked just fine until the wind blew just right one day.

Resonance works in ways that maybe not apparent to people. Maybe it is because your net setup is lighter that this happens.

Edited by gotak, 20 February 2018 - 06:52 AM.

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#56 Real14

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Posted 20 February 2018 - 08:50 AM

" I am just questioning how can stepper motors moving at minimal revolutions per minute and having very small rotors induce such a heavy weight to vibrate ... There must be an outside force which induces to vibrations." 

 

The same force that is able to move that weight, is able to cause vibrations, because of the gear ratio, which is the determining factor for the introduced force, not just the tiny rotors.

I agree some other outside constructional factors may have quite a big influence as well, like a rat cage construction or a too weak pier, which may boost the effect by vibrational resonance, but I do believe this has all been checked and found not applicable. 

 

 

  The same force that is able to move that weight, is able to cause vibrations, because of the gear ratio, which is the determining factor for the introduced force, not just the tiny rotors.

confused1.gif



#57 Real14

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Posted 20 February 2018 - 09:00 AM

 

 

There were in depth of discussion in another thread posted by the same owner and plenty of replies pointed out most likely the vibration was due to improper pier/tripod setup; long bolts formed a "rat cage", and apple on a straw (6" minipier on top of a skinny 4" pier).

Performance on tripod was same as on pier, as stated above. Could they both be bad in an identical way? Also vibrations were not just subtle, affecting astro-images. You could see the whole OTA body shaking, like a tuning fork. And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece. My tripod was used with a number of setups over the years, including much heavier ones, and never showed anything like this. You would need to see the shaking to appreciate the magnitude. This is not just a matter of waiting for vibrations to dampen, but never being in control of when they would start.
The Tacoma narrows bridge is way heavier than any scope setup you had and worked just fine until the wind blew just right one day.

Resonance works in ways that maybe not apparent to people. Maybe it is because your net setup is lighter that this happens.

 

Quoting adastranova

 

 

And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece.

Hi adastranova, there you have the answer to your problems !

 

 

And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece.

You are inducing your setup to a vibration. You posted somewhere images of your 4" steel pipe pier. You touch with the eye your eyepiece and then it vibrates ...

 

Read your own message please ! Read very carefully what gotak has written and you might unbderstand your problem. If you ut your Losmandy G11G on that pier you will have the same problem ....

 

¿ how many people have given you advice to make changes on the pier ? but looks like you do not understand that ...



#58 rmollise

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Posted 20 February 2018 - 09:12 AM

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.


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#59 dvalid

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Posted 20 February 2018 - 09:58 AM

There were in depth of discussion in another thread posted by the same owner and plenty of replies pointed out most likely the vibration was due to improper pier/tripod setup; long bolts formed a "rat cage", and apple on a straw (6" minipier on top of a skinny 4" pier).

 

 

Quoting adastranova

 

 

 

And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece.

You are inducing your setup to a vibration. You posted somewhere images of your 4" steel pipe pier. You touch with the eye your eyepiece and then it vibrates ...

 

Read your own message please ! Read very carefully what gotak has written and you might unbderstand your problem. If you ut your Losmandy G11G on that pier you will have the same problem ....

 

¿ how many people have given you advice to make changes on the pier ? but looks like you do not understand that ...

 

 

Ok, but in my case I do not use any rat cage. My CEM60 sits on a 2" tripod that came with the mount, later I've added iOptron pier .I did try anti vibration pads, added counterweight to shorten the arm - result is the same. 

 

Even focusing is a great challenge, although I've moved the focuser of my 1100HD to the imaging train and keep the mirror locked..

 

Don't get me wrong, in contrast to a more expensive mounts, CEM60 is very user friendly, it works perfectly with my FSQ106 setup, but not with anything heavier. 


Edited by dvalid, 20 February 2018 - 10:05 AM.

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#60 gotak

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Posted 20 February 2018 - 10:52 AM

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

Could be interaction of the spring loaded design with some folk's setups, could be that there is actually a mechanical problem. However, if someone ships it back to iOptron and never took it back after they worked on it, we'll never know if iOptron fixed it or what. This is why what happened for me is a bit disappointing because if iOptron took it back and it wasn't fixed then you have at least one more data point.

 

 

As is everything we have are just guesses. Is the pier an issue? Is there resonance interaction between the load, mount and pier? No one can really tell at this point as 1) the mount is gone 2) we never saw anything but words and a few scant pictures, a video of the vibration would have been nice wouldn't it?

 

Anyhow at this point I think this thread has ran its course and the only conclusion we can really draw is that there is no root cause identified. 


Edited by gotak, 20 February 2018 - 10:53 AM.

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#61 adastranova

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Posted 20 February 2018 - 11:04 AM

 

 

 

There were in depth of discussion in another thread posted by the same owner and plenty of replies pointed out most likely the vibration was due to improper pier/tripod setup; long bolts formed a "rat cage", and apple on a straw (6" minipier on top of a skinny 4" pier).

Performance on tripod was same as on pier, as stated above. Could they both be bad in an identical way? Also vibrations were not just subtle, affecting astro-images. You could see the whole OTA body shaking, like a tuning fork. And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece. My tripod was used with a number of setups over the years, including much heavier ones, and never showed anything like this. You would need to see the shaking to appreciate the magnitude. This is not just a matter of waiting for vibrations to dampen, but never being in control of when they would start.
The Tacoma narrows bridge is way heavier than any scope setup you had and worked just fine until the wind blew just right one day.

Resonance works in ways that maybe not apparent to people. Maybe it is because your net setup is lighter that this happens.

 

Quoting adastranova

 

 

And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece.

Hi adastranova, there you have the answer to your problems !

 

 

And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece.

You are inducing your setup to a vibration. You posted somewhere images of your 4" steel pipe pier. You touch with the eye your eyepiece and then it vibrates ...

 

Read your own message please ! Read very carefully what gotak has written and you might unbderstand your problem. If you ut your Losmandy G11G on that pier you will have the same problem ....

 

¿ how many people have given you advice to make changes on the pier ? but looks like you do not understand that ...

 

I tried a number of changes suggested here and many others, weight distribution, balance, adding and subtracting accessories, etc. and moving from pier to tripod. After removing the mount I also whacked the pier with a large rubber mallet and saw no movement or vibration. But gaining your personal understanding is not my prerogative. 


Edited by adastranova, 20 February 2018 - 11:05 AM.

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#62 Real14

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Posted 20 February 2018 - 11:09 AM

 

 

 

 

There were in depth of discussion in another thread posted by the same owner and plenty of replies pointed out most likely the vibration was due to improper pier/tripod setup; long bolts formed a "rat cage", and apple on a straw (6" minipier on top of a skinny 4" pier).

Performance on tripod was same as on pier, as stated above. Could they both be bad in an identical way? Also vibrations were not just subtle, affecting astro-images. You could see the whole OTA body shaking, like a tuning fork. And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece. My tripod was used with a number of setups over the years, including much heavier ones, and never showed anything like this. You would need to see the shaking to appreciate the magnitude. This is not just a matter of waiting for vibrations to dampen, but never being in control of when they would start.
The Tacoma narrows bridge is way heavier than any scope setup you had and worked just fine until the wind blew just right one day.

Resonance works in ways that maybe not apparent to people. Maybe it is because your net setup is lighter that this happens.

 

Quoting adastranova

 

 

And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece.

Hi adastranova, there you have the answer to your problems !

 

 

And the oscillations start with the slightest provocation, e.g. air moving across dew shield, or touching eye to eyepiece.

You are inducing your setup to a vibration. You posted somewhere images of your 4" steel pipe pier. You touch with the eye your eyepiece and then it vibrates ...

 

Read your own message please ! Read very carefully what gotak has written and you might unbderstand your problem. If you ut your Losmandy G11G on that pier you will have the same problem ....

 

¿ how many people have given you advice to make changes on the pier ? but looks like you do not understand that ...

 

I tried a number of changes suggested here and many others, weight distribution, balance, adding and subtracting accessories, etc. and moving from pier to tripod. After removing the mount I also whacked the pier with a large rubber mallet and saw no movement or vibration. But gaining your personal understanding is not my prerogative. 

 

waytogo.gif

 

Good luck
 



#63 adastranova

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Posted 20 February 2018 - 11:09 AM

 

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

Could be interaction of the spring loaded design with some folk's setups, could be that there is actually a mechanical problem. However, if someone ships it back to iOptron and never took it back after they worked on it, we'll never know if iOptron fixed it or what. This is why what happened for me is a bit disappointing because if iOptron took it back and it wasn't fixed then you have at least one more data point.

 

 

As is everything we have are just guesses. Is the pier an issue? Is there resonance interaction between the load, mount and pier? No one can really tell at this point as 1) the mount is gone 2) we never saw anything but words and a few scant pictures, a video of the vibration would have been nice wouldn't it?

 

Anyhow at this point I think this thread has ran its course and the only conclusion we can really draw is that there is no root cause identified. 

 

I no longer have the mount and have a new one that is satisfactory, so any ultimate solution for those that still have this problem I will not be able to help with.

 

Regards/Cheers



#64 Real14

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Posted 20 February 2018 - 11:10 AM

 

 

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

Could be interaction of the spring loaded design with some folk's setups, could be that there is actually a mechanical problem. However, if someone ships it back to iOptron and never took it back after they worked on it, we'll never know if iOptron fixed it or what. This is why what happened for me is a bit disappointing because if iOptron took it back and it wasn't fixed then you have at least one more data point.

 

 

As is everything we have are just guesses. Is the pier an issue? Is there resonance interaction between the load, mount and pier? No one can really tell at this point as 1) the mount is gone 2) we never saw anything but words and a few scant pictures, a video of the vibration would have been nice wouldn't it?

 

Anyhow at this point I think this thread has ran its course and the only conclusion we can really draw is that there is no root cause identified. 

 

I no longer have the mount and have a new one that is satisfactory, so any ultimate solution for those that still have this problem I will not be able to help with.

 

Regards/Cheers

 

waytogo.gif



#65 Real14

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Posted 20 February 2018 - 11:20 AM

Hi,

 

Tons of help and experience in this dedicated Group

 

https://groups.yahoo...andy_users/info

 



#66 JakeJ

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Posted 20 February 2018 - 03:25 PM

I no longer have the mount and have a new one that is satisfactory, so any ultimate solution for those that still have this problem I will not be able to help with.

 

 

Regards/Cheers

 

Best to move on, ignore the trolls, and let them try to figure out their vibration-prone mounts on their own.

There are plenty of mounts out there that do not have this problem, and plenty of manufacturers who would back up their product.


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#67 gotak

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Posted 20 February 2018 - 05:50 PM


I no longer have the mount and have a new one that is satisfactory, so any ultimate solution for those that still have this problem I will not be able to help with.



Regards/Cheers

Best to move on, ignore the trolls, and let them try to figure out their vibration-prone mounts on their own.
There are plenty of mounts out there that do not have this problem, and plenty of manufacturers who would back up their product.
Pot Kettle? Face->palm.

Edited by gotak, 20 February 2018 - 05:53 PM.


#68 dbjohnso86

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Posted 21 February 2018 - 08:40 PM

I know this thread is old but I just received this same mount today --- Swapping it with the Current Atlas EQ-G that got fried after 10 years of service,  5 of which were on a pier I put in a little over 5 years ago!  Anyway the pier is  8" Diameter  x 1/4" wall thickness steel with a > 6' deep 24" diameter concrete footing and is isolated to the point that only a train across the river from me that goes by every Wednesday shows any visible movement through the eyepiece!  All that said I guess I'll know in a few days if this mount get's the shakes my my pier! I   Sure hope not :)



#69 gotak

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Posted 21 February 2018 - 09:06 PM

I know this thread is old but I just received this same mount today --- Swapping it with the Current Atlas EQ-G that got fried after 10 years of service,  5 of which were on a pier I put in a little over 5 years ago!  Anyway the pier is  8" Diameter  x 1/4" wall thickness steel with a > 6' deep 24" diameter concrete footing and is isolated to the point that only a train across the river from me that goes by every Wednesday shows any visible movement through the eyepiece!  All that said I guess I'll know in a few days if this mount get's the shakes my my pier! I   Sure hope not smile.gif

Wishing you the best.



#70 rmollise

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Posted 22 February 2018 - 01:55 PM

 

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

 

True, but...  I don't recall a single instance of this that was helped in the least with a tripod/pier solution. ;)



#71 AntMan1

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Posted 22 February 2018 - 02:08 PM

 

 

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

 

True, but...  I don't recall a single instance of this that was helped in the least with a tripod/pier solution. wink.gif

 

Reading through most of the reports on here they seem to have 1 thing in common...Bigger heavier scopes.


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#72 gotak

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Posted 22 February 2018 - 03:16 PM

 

 

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

 

True, but...  I don't recall a single instance of this that was helped in the least with a tripod/pier solution. wink.gif

 

There was a thread where the person found that his tri-pier had a lose leg that just didn't tighten down correctly.


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#73 gotak

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Posted 22 February 2018 - 04:06 PM

 

 

 

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

 

True, but...  I don't recall a single instance of this that was helped in the least with a tripod/pier solution. wink.gif

 

Reading through most of the reports on here they seem to have 1 thing in common...Bigger heavier scopes.

 

Not too surprising weight is an issue. the CEM60 is "spring" or magnetically loaded. And the frequency of a harmonic oscillator (assuming we can simplify to such) is entirely dependent on the spring constant and mass only.  

 

Does makes me wonder... has anyone tried tightening up the tension knobs or something like that?


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#74 Real14

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Posted 22 February 2018 - 04:12 PM

 

 

Not too surprising weight is an issue. the CEM60 is "spring" or magnetically loaded. And the frequency of a harmonic oscillator (assuming we can simplify to such) is entirely dependent on the spring constant and mass only. 

 

Does makes me wonder... has anyone tried tightening up the tension knobs or something like that?

Interesting. From outside forces induced vibrations do make the spring or magnetically loaded worm vibrate  and that vibration makes the telescope vibrate too ?

 

Why not ask iOptron if this could be a cause for this vibrations which some mounts do have and some mounts do not have, but more do not have them and just so far I have read of 2 or 3 CEM 60 do have it and all others do not  

 

confused1.gif


Edited by Real14, 23 February 2018 - 10:04 AM.


#75 AntMan1

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Posted 22 February 2018 - 05:07 PM

 

 

 

 

It's been pretty obvious from the beginning that some CEM60s have this problem. Not all, but some. And that no tripod or pier will fix it.

 

I'd say more precisely that some folks have had issues but because no one nailed down the root cause, we have no bloody idea what the problem actually is.

 

 

True, but...  I don't recall a single instance of this that was helped in the least with a tripod/pier solution. wink.gif

 

Reading through most of the reports on here they seem to have 1 thing in common...Bigger heavier scopes.

 

Not too surprising weight is an issue. the CEM60 is "spring" or magnetically loaded. And the frequency of a harmonic oscillator (assuming we can simplify to such) is entirely dependent on the spring constant and mass only.  

 

Does makes me wonder... has anyone tried tightening up the tension knobs or something like that?

 

I know its a different mount but same principle of center balance, my cem25p was unable to accommodate a Stellarvue SV102T in carbon fiber total weight about 14 pounds. A simple usb cable with half its weight supported was causing it issues. After troubleshooting what seemed like a overloaded mount i was told the physical length of the scope and the weight all the way at the tail end contributed to my issues? Hello? anyone home? astrophotography usually entails that type of setupbigshock.gif  


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