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Fixing an old Cave Astrola

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#1 ajkrishock

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Posted 11 October 2021 - 09:29 AM

All,

 

Our astronomy club has an old 16" f/8 Cave Astrola reflector. Earlier this spring, one of the old Bristol motors died and we've been trying to restore it ever since. I understand that Bristol is long gone. Can anyone point me toward some resources on these old scopes and where (if anywhere) I can go to find replacement parts?

 

Thanks

 

Bristol_447.jpg


Edited by ajkrishock, 11 October 2021 - 09:29 AM.


#2 DAVIDG

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Posted 11 October 2021 - 09:40 AM

 If the gear train is still good you can remove it and install in on another Bristol  Saybrook motor of the same model type. They show up on Ebay so do a search for "Bristol  Saybrook motor"  What usually happen is the magnets in the armature will rust and that causes them to loose their magnetism. The gear box comes off and you can install it onto  good armature and the have a working motor. 

 

              - Dave 


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#3 Couder

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Posted 11 October 2021 - 09:45 AM

I had a clock shop for 30 years. If you can't find a replacement, consider: Many of the clocks used a 1 RPM motor, you should be able to find one easy enough. You might have to change how it is mounted, and/or adapt the gear to the new shaft, but those are small things compared to having a 16" Cave working!



#4 apfever

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Posted 11 October 2021 - 10:07 AM

Sorry to drop the subject but I'm a little gone on the 16" F8 part.

Is this a Newtonian?  What size shaft mount? Can we have a picture? Please?



#5 ajkrishock

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Posted 11 October 2021 - 10:14 AM

Here's a few more pictures of the telescope..

 

https://www.cloudyni...6-cave-astrola/


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#6 D_talley

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Posted 11 October 2021 - 10:15 AM

Your shot of the motor is too close. Please take another shot pulled back a little so that we can see the entire motor. Want to make sure they used the same type of motor and mount as their other scopes. As Dave said you can replace the electrical part of the motor with one found on ebay as long as the internal gears are ok.



#7 ajkrishock

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Posted 11 October 2021 - 10:19 AM

Your shot of the motor is too close. Please take another shot pulled back a little so that we can see the entire motor. Want to make sure they used the same type of motor and mount as their other scopes. As Dave said you can replace the electrical part of the motor with one found on ebay as long as the internal gears are ok.

I posted a few more pictures of the motors in my gallery:

 

https://www.cloudyni...6-cave-astrola/



#8 D_talley

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Posted 11 October 2021 - 10:52 AM

Great.  the electrical part pulls away from the gear, they are not screwed together as seen in the attached photos.  I fixed the motor on my Cave scope by replacing the electrical part with one I picked up on ebay.  The rated speed is determined by the gear, not the electrical part. So that is one option for you. There are several for sale on ebay at the moment for around $9.00 

Attached Thumbnails

  • motor1.jpg
  • motor2.jpg
  • motor3.jpg


#9 CHASLX200

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Posted 11 October 2021 - 10:53 AM

Sorry to drop the subject but I'm a little gone on the 16" F8 part.

Is this a Newtonian?  What size shaft mount? Can we have a picture? Please?

It's the dream Cave i always wanted. But with a 150lb+ OTA i won't be lifting it.  It's a Newt on the 2.5" shaft mount.


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#10 ajkrishock

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Posted 11 October 2021 - 11:10 AM

Great.  the electrical part pulls away from the gear, they are not screwed together as seen in the attached photos.  I fixed the motor on my Cave scope by replacing the electrical part with one I picked up on ebay.  The rated speed is determined by the gear, not the electrical part. So that is one option for you. There are several for sale on ebay at the moment for around $9.00 

Appreciate the information. I assume by "electrical part", you're referring to the half of the motor assembly with wires.. not the other part. What is that part called, specifically? What's the search term?



#11 tim53

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Posted 11 October 2021 - 11:14 AM

 Cool!  The observatory mount.  Is it a permanent pier?  or on wheels (like the 12.5" f/7 I sold some months back).


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#12 D_talley

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Posted 11 October 2021 - 11:31 AM

Correct, the electrical part is the assembly with wires. The other side is the gears.  I did a search on your model and motor name --  447  Bristol Saybrook.  I did not search for just the electrical part since they normally are attached to the complete motor.  No clue what it is called.



#13 ajkrishock

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Posted 11 October 2021 - 11:55 AM

Correct, the electrical part is the assembly with wires. The other side is the gears.  I did a search on your model and motor name --  447  Bristol Saybrook.  I did not search for just the electrical part since they normally are attached to the complete motor.  No clue what it is called.

So, just to make sure I understand you, I can use the "electrical part" of this motor:

 

https://www.ebay.com...KQAAOSwtyxeqknl

 

As a replacement for my old motor, correct? 



#14 ajkrishock

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Posted 11 October 2021 - 11:56 AM

 Cool!  The observatory mount.  Is it a permanent pier?  or on wheels (like the 12.5" f/7 I sold some months back).

It's a permanent pier.


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#15 D_talley

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Posted 11 October 2021 - 12:25 PM

No, you have a MOD 447 and that is a MOD 930 which does not have the holes on the sides.   I will keep an eye out for one that will work for your setup.



#16 ajkrishock

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Posted 11 October 2021 - 12:27 PM

No, you have a MOD 447 and that is a MOD 930 which does not have the holes on the sides.   I will keep an eye out for one that will work for your setup.

What about this one?

 

https://www.ebay.com...8.c101113.m2108



#17 D_talley

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Posted 11 October 2021 - 12:53 PM

That would be one I would get.  A little expensive but not many choices.




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