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Late 60s Cave 10" f/7 restoration project

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#1 tim53

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Posted 03 December 2022 - 05:43 PM

And boy does it need it.  Good news is that there are two tube weight sets on this thing, a 2" Sky Micro Giant focuser, and a 360 degree Dec drive (though the Hurst motor likely is junk.  Fortunately, I've got a couple NOS Hurst motors somewhere in my shop)

 

 

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#2 tim53

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Posted 03 December 2022 - 05:44 PM

I'm just loading these pics as I'm pulling them off my phone, so the order doesn't make much sense.  That first one is me trying to loosen the latitude lock set screw.  It's pretty rusted in place, so will need a dose of penetrating oil.

 

 

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#3 tim53

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Posted 03 December 2022 - 05:46 PM

The OTA, above, must be an f/7.  It's about 6 ft tall.  This shows the tube weight sets with 3 weights in attendance.

 

 

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#4 tim53

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Posted 03 December 2022 - 05:46 PM

That pic is of the mount after I'd attached the legs and before I tipped it out of the van to the ground.

 

 

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#5 tim53

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Posted 03 December 2022 - 05:47 PM

And that shows the rusty steel pier with round holes for mounting the legs.


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#6 tim53

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Posted 03 December 2022 - 05:48 PM

The legs:

 

 

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#7 rob1986

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Posted 03 December 2022 - 05:57 PM

wow. how are the optics and their associated mechanics?



#8 tim53

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Posted 03 December 2022 - 06:07 PM

The primary is a bit translucent, but shiny. I need to pull the mirror and look for specs. 


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#9 Bomber Bob

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Posted 03 December 2022 - 06:33 PM

Sweet!  Congrats!!



#10 tim53

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Posted 03 December 2022 - 06:43 PM

Man I hate the latest update to iOS. It used to be easy to email photos to myself so I could reduce their sizes.  Ow I have a couple hoops to jump through. 
 

the mirror could use a recoat, but it’s not bad at all

 

there was actual mud on the mirror, but I washed it off. It was apparently purchased from telescopics as a kit. It’s a cast Pyrex blank with the step around the rim back side. Not a raised rim like my later Pyrex mirrors. There were a couple names engraved in the back, and f/7. But the names are scratched out. One is either Douglass or Donald Allen. The other is harder to read, but looks like Daniel burrell or something similar. 
 

around the edge is 

“Refigured by Cave Optical Co” in script lettering, and

R672789 f/6.8 68 1/4” F.L. July 25, 1967

 

tim


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#11 cavedweller

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Posted 03 December 2022 - 07:52 PM

That is about the condition of a 12.5" F/5 Cave I brought home a year ago. I will be watching your restoration to give me an idea of what is ahead of me.


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#12 icomet

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Posted 04 December 2022 - 11:34 AM

I like what the previous owner did with the rust and corrosion highlights.  grin.gif 

 

Clear Skies. 


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#13 icomet

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Posted 04 December 2022 - 01:53 PM

I'll have you know, Tim's not saying anything about the other scope he was considering at the same time 

with the Cave 10".

 

Here, I'll let you in on it.

 

Clear Skies. 

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Edited by icomet, 04 December 2022 - 01:54 PM.

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#14 Chris Cook

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Posted 04 December 2022 - 01:58 PM

Great find!!

Enjoying the restoration.



#15 Kasmos

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Posted 04 December 2022 - 03:48 PM

Tim, when you commented on this scope in the ads thread you said something like, "too many projects and no room in the shop".

 

What made you Cave and where will it fall on the project list? wink.png


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#16 tim53

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Posted 04 December 2022 - 05:41 PM

I caved because it didn't look like anybody else was going to save it.  And judging from the seller's other "projects", I'm not sure it wouldn't have ended up in a dumpster.  I parked my van over a mud puddle so we wouldn't have to step in it to load the scope.

 

It's good it's not an f/8, because my shop ceiling is maybe 7 ft, probably. more like 6' 8", so I can stand the OTA up and it has about a square ft footprint.  The mount's currently outside until I can get it apart.

 

-Tim.


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#17 CHASLX200

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Posted 04 December 2022 - 07:18 PM

I caved because it didn't look like anybody else was going to save it.  And judging from the seller's other "projects", I'm not sure it wouldn't have ended up in a dumpster.  I parked my van over a mud puddle so we wouldn't have to step in it to load the scope.

 

It's good it's not an f/8, because my shop ceiling is maybe 7 ft, probably. more like 6' 8", so I can stand the OTA up and it has about a square ft footprint.  The mount's currently outside until I can get it apart.

 

-Tim.

Mount looks to be just like the one i had on a 1965 made 10" F/8 Cave.


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#18 dgreyson

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Posted 05 December 2022 - 11:53 AM

Nice find Tim. Synchronous motors usually only fail because the grease has dried out into solid wax and binds the gear train. If you're going to toss the motor anyway, try re hydrating the grease first. I haven't found an antique clock motor I couldn't get working again. Get a fine small drill bit and carefully perforate the gear housing. Be careful not to get metal shavings inside. Then inject a generous amount of penetrating oil and shake it up awhile, then shake out the dirty oil from the housing. Usually takes a few cycles to get it clean. I will be surprised if your motor doesn't work again. Seal the hole with silicone caulk etc and if it doesn't restore it to operation you haven't lost anything.
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#19 tim53

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Posted 05 December 2022 - 12:56 PM

Nice find Tim. Synchronous motors usually only fail because the grease has dried out into solid wax and binds the gear train. If you're going to toss the motor anyway, try re hydrating the grease first. I haven't found an antique clock motor I couldn't get working again. Get a fine small drill bit and carefully perforate the gear housing. Be careful not to get metal shavings inside. Then inject a generous amount of penetrating oil and shake it up awhile, then shake out the dirty oil from the housing. Usually takes a few cycles to get it clean. I will be surprised if your motor doesn't work again. Seal the hole with silicone caulk etc and if it doesn't restore it to operation you haven't lost anything.

I would try to revive it, but the cover is missing  and likely has been for years, so the internals are badly weathered.  I'll try to take a pic of it at some point.



#20 NinePlanets

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Posted 05 December 2022 - 01:03 PM

I wonder if CorrosionX would work on a badly corroded motor. Winding insulation? Don't know. Never tried it, but it sure works wonders on iron oxide.



#21 tim53

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Posted 05 December 2022 - 01:05 PM

I realized I have a picture that I could sharpen:  

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#22 apfever

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Posted 05 December 2022 - 02:20 PM

It looks nice to me. I'd take the motor apart as far as I could mechanically and still get it back together. Then I'd drop anything with rust into some evaporust type dissolver. You will probably be getting a gallon or two of that type dissolver for the resto anyway. The motor reduction box can get two small holes, on opposite sides, just big enough for the smallest straws on spray lube type cans. Much smaller holes if you use a hypodermic. Then you can flush a blast of whatever through the gear box - each way. Maybe fill the gearbox with solvent and quickly flip it to set it in a shallow pan of solvent to soak. That way the solvent won't run out the top or into any motor parts soldered on or riveted.  Maybe just throw that ugly rusted butt ugly mass of motor in the garbage. 


Edited by apfever, 05 December 2022 - 02:41 PM.

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#23 apfever

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Posted 05 December 2022 - 02:41 PM

Ung. Caution. I just checked the DEC drive on my 8" Cave that is very similar. It is Hurst motor and 360 brass gear in a clutch hub. Your motor attachment looks the same for what I can see. If yours is the same as mine then this is all bass ackwards. Mine has the motor attached to the saddle and the gear clutch plates are attached to the DEC housing. This makes the clutch stay still while the motor tracks around the gear along with the DEC shaft and saddle. My motor does clear the RA housing but it would eventually wind up the wires if not careful. This could make a difference on how you check things for movement. 

 

I looked at some other larger GEM mounts with 360 clutch DEC drives and they were all 'normal' with the clutch on the shaft and the motor on a backing plate that attached to the DEC housing. 


Edited by apfever, 05 December 2022 - 02:42 PM.

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#24 Compressorguy

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Posted 05 December 2022 - 03:54 PM

Man I hate the latest update to iOS. It used to be easy to email photos to myself so I could reduce their sizes.  Ow I have a couple hoops to jump through. 
 

tim

By far the best and easiest photo resizing app I’ve used. Maybe it could help someone. Plus it allows deletion of the large original so you don’t end up with a bunch of duplicates.

 

58226404-47B8-43E6-8D96-CEA5ACA1277A.jpeg

 

 

BTW Nice score on the Cave. It would have been very difficult to let that pass if it were close to me and would love to have another someday. Especially a 10” f6, f7 or f8


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#25 tim53

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Posted 06 December 2022 - 12:48 PM

This morning I remembered to squirt a bunch of penetrating oil on all the rusty bolts and counterweight/shaft interfaces on the mount.  I'd take a picture, but it's rather messy looking with all them runs down the pier and stuff.  But if I can free things up enough to be able to use the mount to hold the tube off the ground tomorrow night, I might try this puppy out on the Mars occultation.  Of course, Mars needs to also be visible, and the forecast so far is for partly cloudy skies.  Same as now, where maybe 30% of the sky isn't cloudy.

 

-Tim.




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