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Alt Az mount balancing problem

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#1 BDS316

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Posted 18 January 2020 - 09:52 PM

Hi, looking for a solution to my Stellarvue 80mm f7 Aplanat / M1 mount balancing issue, there's too much weight at the focuser end. 2 inch diagonal and none of my eyepieces are super heavy.

I tried changing the dovetail rail position in the M1..didn't help. I need I think some kind of weight at the objective end of the scope to prevent backlash when the scope is moved to point lower.


Any suggestions? Thanks

#2 Gary Z

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Posted 18 January 2020 - 10:03 PM

Just offering up suggestions; it's understandable if you've already considered or done these:

 

1) Extend out the dew shield.

2) use a longer dovetail so that you can use the longer length to achieve your proper balance of your scope and gear and if need be add more metal at the objective end to assist in balancing out.

3) Look for a lighter 2 inch diagonal. 



#3 BDS316

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Posted 18 January 2020 - 10:10 PM

Just offering up suggestions; it's understandable if you've already considered or done these:

1) Extend out the dew shield.
2) use a longer dovetail so that you can use the longer length to achieve your proper balance of your scope and gear and if need be add more metal at the objective end to assist in balancing out.
3) Look for a lighter 2 inch diagonal.


Extending dew shield was first thing I tried. I have as far as I can tell the lightest diagonal, and the dovetail is attached to the scope.

Thanks for responding.

#4 coopman

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Posted 18 January 2020 - 10:22 PM

Try an ankle weight at the objective end.



#5 desertlens

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Posted 19 January 2020 - 12:32 AM

I'm not familiar with the scope in question but if the dovetail is of the "foot" style, you could add a longer bar between it and the mount saddle. I'm thinking something similar to this setup which uses a short bar since the foot is not actually a dovetail. You could use a longer bar if your foot has at least 2, 1/4"-20 holes.

 

AT60EDsv.jpg


Edited by desertlens, 19 January 2020 - 12:41 AM.

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#6 McNewt

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Posted 19 January 2020 - 06:06 AM

I have one of these on order https://www.firstlig...nterweight.html and I already have a rather long dovetail that I will try an see if it fits on my 80mm refractor later today.   Intent is to have the dovetail sticking out the front and mount the balance weight there, but since I don't have it yet I will mount it the other way in order to slide the scope forward.    I dearly hope that nothing is in the way.  If that is the case I need to find a solution to that too.    I'll report back.



#7 Jon Isaacs

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Posted 19 January 2020 - 06:19 AM

Hi, looking for a solution to my Stellarvue 80mm f7 Aplanat / M1 mount balancing issue, there's too much weight at the focuser end. 2 inch diagonal and none of my eyepieces are super heavy.

I tried changing the dovetail rail position in the M1..didn't help. I need I think some kind of weight at the objective end of the scope to prevent backlash when the scope is moved to point lower.


Any suggestions? Thanks

Bryan:

 

A photo of the scope on the mount would be helpful.  Shifting the scope forward should be effective if there's room enough.  

 

The M1 mount has adjustable friction so that should be part of the equation.  

 

Jon



#8 McNewt

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Posted 19 January 2020 - 07:57 AM

I have about 3mm of clearance to the dewshield and, not visible, about a milliliter clearance to the dewcap.  I this orientation, moving the scope forward is not possible without some kind of shim due to the focuser lock screw blocking the way.  On an AltAz mount it is rotated 90 degrees so that is all fine.   (The holes on this dovetail have UNC threads and the threads on the scope rings are metric.  Need to do some drilling before I can proceed.)

 

 

dovetail_small.jpg



#9 clearwaterdave

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Posted 19 January 2020 - 08:15 AM

I put a strip of lead flashing inside of the dewsheild on my Nexstar.,works all good.,Mason's use it on chimneys.,good luck.,



#10 BDS316

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Posted 19 January 2020 - 11:11 AM

Bryan:

A photo of the scope on the mount would be helpful. Shifting the scope forward should be effective if there's room enough.

The M1 mount has adjustable friction so that should be part of the equation.

Jon

Hi Jon,

I shifted the scope and the dovetail forward but you're right there's not enough room.

Yes friction is adjustable but tightening it makes the motion very jerky and unpredictable.

I can't post photos because I'm one of those older techno phobic guys.

My concern is that if I'm having balancing issues with light eyepieces like a 32mm plossl and a 30mm Superview, imagine what would happen with anchors like a 31mm Nagler or a 35 Pan.

Bryan

Edited by BDS316, 19 January 2020 - 11:48 AM.


#11 luxo II

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Posted 19 January 2020 - 09:42 PM

A Velcro adhesive dot on the dewcap to secure a beanbag or two should fix this easily.

Or find a strip of double-sided Velcro long enough to wrap around, and secure with that. Even sticky tape would do, in a pinch.

Or a dot of Bluetack - and a metal weight (got a fishing sinker ?)...

C’mon guys let’s see some ingenuity.

Edited by luxo II, 19 January 2020 - 09:43 PM.


#12 cturek

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Posted 20 January 2020 - 01:29 PM

This is what I made to add weight to the front of a small OTA with heavy accessories in the back. I can adust the weight front/rear/up/down and also angled forward or towards the rear. I have an identical assembly that comes off straight from the Vixen bar if the OTA is mounted with the bar on the bottom.

 

 

Attached Thumbnails

  • C6 OTA Front Weight 2.jpg

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#13 Im2bent

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Posted 20 January 2020 - 03:07 PM

Can you loosen the rings and slide the scope further forward thus giving you more leverage?



#14 BDS316

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Posted 21 January 2020 - 08:44 AM

Can you loosen the rings and slide the scope further forward thus giving you more leverage?

Tried that.  Thanks for responding



#15 photoracer18

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Posted 21 January 2020 - 05:25 PM

Hi, looking for a solution to my Stellarvue 80mm f7 Aplanat / M1 mount balancing issue, there's too much weight at the focuser end. 2 inch diagonal and none of my eyepieces are super heavy.

I tried changing the dovetail rail position in the M1..didn't help. I need I think some kind of weight at the objective end of the scope to prevent backlash when the scope is moved to point lower.


Any suggestions? Thanks

Add a 90mm ring to the front of the tube and attach a weight to it with a screw. Then you can slide it up and down to balance any other parts you may add at the back.



#16 houndsbourgh

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Posted 21 January 2020 - 06:46 PM

I think cturek has a great idea. As the scope reaches vertical longer dovetails and inline counterweights become less effective. Off axis counterweights create a new dynamic (3D load) with more consistent loads throughout the axis rotation. For its size an off axis counterweigh can be very effective.




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