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Inherited a 12.5” Cave with mount and mobile pier

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#1 MR2TOYOU

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Posted 14 October 2019 - 04:03 PM

Hello everyone I recently inherited this beautiful telescope. I don’t know much about it other than the mirrors were redone early this year and it has some kind of modified hand box for mount control. It looks to be home made and has two displays. The RA begins tracking when the upper display is turned on. It doesn’t have encoders or anything special and the “dec” motor is attached to an arm under the telescope that is attached to a horizontal worm gear. I’m not really sure what this does or what it is called. I also haven’t found any clutches if there is any. The scope is perfectly balanced and stays where it’s put for viewing. I haven’t tested the tracking ability as I have only opened the garage door to peek at the moon and Orion. Wow but that’s another topic lol. I don’t think it would track with some clutch engaged. I am also not sure exactly what 12.5” this is other than the identifying arm below the OTA making me think it’s the F7 model. Is there a good source about the features of this telescope etc.  I will include more images of the HC etc  when I get home but here is the beast 

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#2 dgreyson

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Posted 14 October 2019 - 05:48 PM

The instructions from cave are available online as well as the catalog but they dont really tell you much. Someone else should have the archive url for telescope manuals hopefully, I don't recall it.
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#3 MR2TOYOU

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Posted 14 October 2019 - 06:47 PM

Wow, not much info there haha. Here’s a picture of the hand box. I’m not sure if it was something he made or if he purchased it. Upon closer inspection it appears that that arm is just a slight dec adjustment for centering or something. It can only move a few degrees I’m running the motors now to see if the telescope moves with tracking as there’s no clutches. 

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Edited by MR2TOYOU, 15 October 2019 - 07:46 AM.


#4 Russell Smith

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Posted 14 October 2019 - 07:59 PM

Beast seems appropriate.
Sorry for your loss.
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#5 Russell Smith

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Posted 14 October 2019 - 10:58 PM

****
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#6 Mr Magoo

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Posted 15 October 2019 - 08:45 AM

Very cool. You should get some great views with that. 


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#7 macdonjh

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Posted 15 October 2019 - 01:33 PM

Hello everyone I recently inherited this beautiful telescope. I don’t know much about it other than the mirrors were redone early this year and it has some kind of modified hand box for mount control. It looks to be home made and has two displays. The RA begins tracking when the upper display is turned on. It doesn’t have encoders or anything special and the “dec” motor is attached to an arm under the telescope that is attached to a horizontal worm gear.

 

I’m not really sure what this does or what it is called. That's a "tangent arm".  You are correct in thinking its purpose is to allow limited movement of the mount in declination to track objects and keep them centered for viewing or photographing.  The assumption is your mount will be correctly polar aligned before you start so almost all moving the mount does will be with the RA axis to track.

 

also haven’t found any clutches if there is any. There may not be any, but look again for them.  Slip clutches are very helpful on "push-to" mounts like yours.  They allow you to push the scope to the object you want to observe and then the mount resumes tracking without you having to tighten anything. 

 

The scope is perfectly balanced and stays where it’s put for viewing. I haven’t tested the tracking ability as I have only opened the garage door to peek at the moon and Orion. If you didn't have to constantly adjust the scope's position to keep the moon or Orion centered, your mount was tracking.  At least the RA axis motor works.

 

Wow but that’s another topic lol. I don’t think it would track with some clutch engaged. If there aren't clutches, the mount will track as long as the motor is running and the gears are meshed.  If there are clutches, then the motor has to be running, the gears meshed and the clutch engaged (tightened).

 

I am also not sure exactly what 12.5” this is other than the identifying arm below the OTA making me think it’s the F7 model. Measure the length of the scope's tube.  An f/5 will be a few inches longer than 62 1/2" long, and f/7 will be a bit longer than 87 1/2" long. 

 

Is there a good source about the features of this telescope etc.  I will include more images of the HC etc  when I get home but here is the beast 

Please accept my condolences for your loss and congratulations for your new scope.  Some comments are in red above. 


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#8 macdonjh

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Posted 15 October 2019 - 01:37 PM

MR2TOYOU, if you're able to post pictures of each side of the declination axis the Cave experts here will be able to tell you what mount you have and probably everything you ever wanted to know about it.  The Astrola mounts I've seen have "Astrola" cast into the declination axis housing, parallel to the axis/ shaft.

 

A couple of close-ups of the rear end of the RA housing may also provide enough information for somebody to tell you where the clutch is and how to tighten/ loosen it.


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#9 Mr Magoo

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Posted 15 October 2019 - 07:02 PM

Looks like and older model judging by the style of tangent arm. 


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#10 Russell Smith

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Posted 15 October 2019 - 07:05 PM

Film Astrophotography comes to mind.


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#11 icomet

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Posted 16 October 2019 - 10:59 AM

Without measurements, etc. here goes on an ID for you:

 

Pier looks like an 8 1/2" diameter one, and maybe the  Dec

shaft would possibly then be 2".

 

Can't see if there are two sets of primary mirror cell holes

in the tube. This would account, I think for counter wts. 

up at the focuser end; scope set up for astrophotography 

use. Hence, the real heavy pier.

 

I have a 12.5" f/7 "portable" observatory scope with what I stated above. This was put together from 1961-1964. Not many with a 2" shaft, as told to be by all real helpful guys on CN, when I was trying to ID mine. I have no markings on the mirror, unfortuneatley, to narrow it down, but I did learn something, the other day when surfing CN forums. Tube construction wasn't consistant, and mine is fiberglass over some sort of insert, like hard cardboard. It's inside thickness isn't consistant, either. It was said that this was done in 1962.

 

Take some measurements, look for mirror id marks, and go from there.

 

I will be upgrading my "control box" also. If you've ever seen and original one, you'll see why it was done. I will also be rewiring the whole scope, too.

 

Nice scope and I hope it stays in one piece. I drove 2600+ miles, round trip to rescue the one that I acquired from a Midwest University. (Yes, the price was right to do this)

 

Clear Skies.


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#12 CHASLX200

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Posted 16 October 2019 - 05:59 PM

Without measurements, etc. here goes on an ID for you:

 

Pier looks like an 8 1/2" diameter one, and maybe the  Dec

shaft would possibly then be 2".

 

Can't see if there are two sets of primary mirror cell holes

in the tube. This would account, I think for counter wts. 

up at the focuser end; scope set up for astrophotography 

use. Hence, the real heavy pier.

 

I have a 12.5" f/7 "portable" observatory scope with what I stated above. This was put together from 1961-1964. Not many with a 2" shaft, as told to be by all real helpful guys on CN, when I was trying to ID mine. I have no markings on the mirror, unfortuneatley, to narrow it down, but I did learn something, the other day when surfing CN forums. Tube construction wasn't consistant, and mine is fiberglass over some sort of insert, like hard cardboard. It's inside thickness isn't consistant, either. It was said that this was done in 1962.

 

Take some measurements, look for mirror id marks, and go from there.

 

I will be upgrading my "control box" also. If you've ever seen and original one, you'll see why it was done. I will also be rewiring the whole scope, too.

 

Nice scope and I hope it stays in one piece. I drove 2600+ miles, round trip to rescue the one that I acquired from a Midwest University. (Yes, the price was right to do this)

 

Clear Skies.

Cave used a few diff tube makers over the years. Even Meade Fiberlite tubes near the end. Most seem to be Parks tubes.



#13 MR2TOYOU

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Posted 05 November 2019 - 10:42 AM

Hey again so I’ve got some photos/measurements. The tube is 76” long going over the rotator rings and cradle so I’m guessing about 75” actual length. The tube is 15.75” across I haven’t measured the actual mirror yet. The focuser has a rubber spacer between it and the tube. This will most likely be the first thing I work on. Is there a low profile focuser that might allow my DSLR to come into focus for prime focus AP?  It seams there’s a lot of holes from either being worn out or this is t the original focuser. Is there anything else I should measure? Thanks and clear skies! 

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#14 tim53

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Posted 05 November 2019 - 11:50 AM

That’s a sky micro giant focuser. I wouldn’t change it. 


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#15 John Higbee

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Posted 06 November 2019 - 07:08 AM

looks like a Cave 12.5" f/6 Model D Transportable to me.  If the mount shafts are actually 2" in diameter, you have a very desirable observatory mount.


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#16 MR2TOYOU

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Posted 07 November 2019 - 12:36 PM

Is there any companies that still offer encoders etc to make those computer controlled? JMI is a definite no unless there’s NOS somewhere lol. I’m quite pleased with the views of this beast. I would love to photograph with it! 



#17 MR2TOYOU

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Posted 07 November 2019 - 12:39 PM

That’s a sky micro giant focuser. I wouldn’t change it. 

It was just the easiest option I was considering for reaching focus with my DSLR. I’m wondering if I remove that foam between the ota and the focuser and re fiberglass the tube so I can mount the fixer directly to it if I will then be able to make focus. 



#18 photoracer18

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Posted 07 November 2019 - 03:45 PM

Normally the SMG focuser is mounted on a skirt that conforms to the curvature of the tube. You would need to make that part.

Those drive motors are not Cave original even for the early 60's. Should be Hurst CA AC synchronous. Those look more like steppers. And the mount looks newer than early 60's as its totally different than the one on my early 60's Cave 12.5 Convertible Cass/Newt Observatory Model which has a pre-roller bearing version with a 2" RA and a 1.5" DEC. Of course its possible mine is actually older.


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#19 dhferguson

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Posted 07 November 2019 - 03:59 PM

Cheers,

 

Regarding encoder kits, try Argo Navis. I believe they still offer the same kit as their distributor JMI once did. Do see my notes on it in a separate post, however.

 

Happy observing always,

 

Don


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#20 photoracer18

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Posted 11 November 2019 - 05:51 PM

The thing is with GEMs the encoder gear has to be on the axis shafts unless the encoders goes right down the center of the axis shafts themselves. Which does not work on the DEC as they have a single shaft from the cradle to the end of the CW end of the shaft.

Used to be that the Magellan I and II kits for the Meade DS-16 contained the encoders and gears for their 1.5" shaft sizes (I had a Magellan I kit for the DS-16 that had all that stuff and I was going to use my Argo Navis on that. The only large GEM that JMI made encoder gears for was the Meade DS-16. All used a 2:1 ratio on the DS-16 so 4k encoders functioned as 8K encoders, or in the case of JMI they used 10K large body encoders.


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#21 tim53

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Posted 14 November 2019 - 10:32 AM

looks like a Cave 12.5" f/6 Model D Transportable to me.  If the mount shafts are actually 2" in diameter, you have a very desirable observatory mount.

It looks like a 1 1/2" shaft mount to me.

 

-Tim.


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#22 CHASLX200

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Posted 14 November 2019 - 11:43 AM

The Observatory mount had 2.5" shafts.


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#23 MR2TOYOU

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Posted 14 November 2019 - 03:47 PM

should I measure the end of the counter weight shaft for the correct measurement or do I need to use the main RA shaft? I'll measure more accurately tonight



#24 tim53

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Posted 14 November 2019 - 08:06 PM

should I measure the end of the counter weight shaft for the correct measurement or do I need to use the main RA shaft? I'll measure more accurately tonight

It would depend on the vintage.  But I think it was only the very early mounts that had different size RA and Dec shafts (shalves?).

 

Your scope looks like it's from the 70s, so it would likely have 1.5" shafts.  

 

Here's what the 2.5" shaft Observatory mount looks like.  It's a real monster:  post-6788-14073919076626_thumb.jpg


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#25 clamchip

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Posted 14 November 2019 - 09:08 PM

Monster is right, my god. Now that's a mount.

The mount is the foundation, very important as we all know.

You won't be putting that in the family stationwagon.

If I remember correctly (harder and harder these days) Cave defined the "semi-transportable" as

one you can transport in the 'family stationwagon' the stationwagon was a huge vessel at the time

easily able to handle full sheets of plywood. The 'observatory' mount is obviously in a whole different

category.

 

Robert




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