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Mr Magoo's Cave

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#101 CHASLX200

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Posted 07 December 2018 - 06:45 PM

I know Cave was using any tubes they could get near the end. Paper wound tubes and Meade Fiberlites.


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#102 Mr Magoo

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Posted 07 December 2018 - 11:54 PM

Ken - no.  That is the Cave I got in 2012 from a fellow CNer in upstate New York.  It dates to March 1979...the optics are very good; the tube is a Sonotube, focuser is a 2"/1.25" Meade, the declination drive uses a segment arm, and the setting circles are Bakelite.  The mount and the pier are in excellent condition, and the legs are set up on casters...so I can roll it out of my garage on demand.

 

The Cave I've mentioned on your topic dates to mid-1975...was privately owned, then donated to a university from which I purchased it (they had used it for several decades).  Haven't star tested it yet.  The tube is a Parks product, focuser is 1.25" only, the dec drive uses a shaft mounted gear, and the setting circles are engraved aluminum.  It came without a pier or legs, but the university threw in three very large Edmund Scientific legs (probably from a '60's vintage 8" reflector that they no longer have). 

 

attachicon.gif new Cave tube.JPG

 

John

Very nice!



#103 Mr Magoo

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Posted 09 December 2018 - 12:46 AM

Well, I made a rather embarrassing mistake. As a sheet metal worker for more than 30 years I should know better than to trust someone's measurements.

 

I cleaned carpets most of the day and was relegated to the garage while they dried. To keep myself occupied I decided to finish stripping the OTA of all its accessories. As I removed the end rings I thought boy that tube looks bigger than the 14.5" that I was told. Grabbed my tape and lo and behold it is 15 5/16" O.D! I felt pretty darn stupid at that point and checked it a few more times. I figured out that they were measuring the inside of the end rings.  

 

My apologies to everyone for getting it so darn wrong. Still can't believe I did that. I'm always preaching to my guys to never trust anyone's info, not even mine. Measure twice cut once right? I took two showers to get the egg off my face. 

 

So as Paul Harvey would say, now for the rest of the story. My tube is 15.3125" O.D. as I just mentioned and the I.D. of the rotating rings are about 16". Now I see why they had to use the 16" rings. My question now is is this normal to have a tube over 15" O.D. with the rings 16" and a bunch of shims? Mine was shimmed with some sort of white plastic about 3/16" and 1/4" thick cork. 

 

What I think I will do when I put it back together is to fabricate a shim from aluminum flat bar and attach it either to the tube or the ring and then use a strip of cork to fill the rest. I thought that if I attached the flat bar ring to the OTA then I could put the rings on without the worry of marring the tube. 

 

Oh and I haven't counted them yet, but there are a bunch of extra holes in this tube. The oddest ones are on the rear end in line with the mirror cell holes, but more than 12" away from the end. Maybe they had a shorter focal length mirror in it at one time, who knows. 

 

I have identified what a lot of the others are for. I am missing one counterpoise bracket. Don Rothman may have one in his warehouse of stuff. 


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#104 Geo31

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Posted 09 December 2018 - 08:55 AM

Ken, the tube diameter you have is not standard,  As others have said, apparently Cave had to get more creative in sourcing in the later years and I suspect that is the issue here.

 

The shims you describe should work fine.  I assume you’ll add some curvature to them.

 

I would assume the second holes for the mirror cell were for imaging (move the mirror up), but 12” seems extreme.  How far up are the “normal” holes?


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#105 CHASLX200

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Posted 09 December 2018 - 09:31 AM

Ken, the tube diameter you have is not standard,  As others have said, apparently Cave had to get more creative in sourcing in the later years and I suspect that is the issue here.

 

The shims you describe should work fine.  I assume you’ll add some curvature to them.

 

I would assume the second holes for the mirror cell were for imaging (move the mirror up), but 12” seems extreme.  How far up are the “normal” holes?

I saw a late 70's 12.5" F/5 Cave with a spiral wrap inside the OTA many years ago.  I think it could have been a Meade Fiberlite tube.  Parks always seems to have a rough inside with a clean seam and have that Parks smell that not other tube maker gave us.  I know that Parks smell a mile away. Even tubes that are 50 years old have that Parks smell when ya stick your head in there and sniff.

 

Guess i am a tube sniffer. Better than glue sniffing i guess.  Seems tube OD's also would vary by maker and years that Cave used.  All in all it seemed Cave used Parks until around 1976 then it was all over the board.

 

As for extra set of mirror cell holes, 1 to 1.5" seem to be the norm that i have seen.


Edited by CHASLX200, 09 December 2018 - 09:32 AM.

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#106 Mr Magoo

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Posted 09 December 2018 - 12:44 PM

Ken, the tube diameter you have is not standard,  As others have said, apparently Cave had to get more creative in sourcing in the later years and I suspect that is the issue here.

 

The shims you describe should work fine.  I assume you’ll add some curvature to them.

 

I would assume the second holes for the mirror cell were for imaging (move the mirror up), but 12” seems extreme.  How far up are the “normal” holes?

I will get a piece of aluminum flat bar and roll it up to the correct I.D. 

 

The mirror cell holes closest to the end are right at 2". There is another set at 3.375" and then the other holes that line up with them are at 14.5" from the end. 

 

I counted all the holes (including the focuser hole) in the tube and the grand total is 65 holes! What the heck lol! So what is the best method to fill holes in a fiberglass tube? 



#107 TOM KIEHL

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Posted 09 December 2018 - 03:00 PM

 So what is the best method to fill holes in a fiberglass tube? 

 

I use this https://www.smooth-o...products/mt-13/  with blue painters tape to back up the hole on the OD. and fill the hole from inside .  Can't reach the inside ? ..... put a glob of mixed epoxy on sticky side of blue painter tape , and press into hole and smooth tape over till hard , then remove the tape .

 

 

The best part of this product is IT'S WHITE !
 


Edited by TOM KIEHL, 09 December 2018 - 03:02 PM.

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#108 CHASLX200

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Posted 09 December 2018 - 03:31 PM

I use this https://www.smooth-o...products/mt-13/  with blue painters tape to back up the hole on the OD. and fill the hole from inside .  Can't reach the inside ? ..... put a glob of mixed epoxy on sticky side of blue painter tape , and press into hole and smooth tape over till hard , then remove the tape .

 

 

The best part of this product is IT'S WHITE !
 

So how do you order it? I sure don't need a big bucket of it. 


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#109 TOM KIEHL

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Posted 09 December 2018 - 03:46 PM

So how do you order it? I sure don't need a big bucket of it. 

Duh foreheadslap.gif ohmy.gif  https://www.amazon.c...e/dp/B06XGNC42B



#110 CHASLX200

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Posted 10 December 2018 - 06:22 AM

Perfect. Better than caulk.


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#111 Mr Magoo

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Posted 29 December 2018 - 04:18 PM

Working a lot of OT lately has not left me time to do much of anything. I had been soaking the stuck counterweight for several weeks in penetrant with no luck in getting it to move.

 

I decided to get a more aggressive with it and took it to work with me to put some pressure on it. I rigged up a poor man's shop press by welding together three of my shop horses and putting a 10 ton Porta Power in between them and the shaft. After about 6 pumps on the ram it let loose with a big pop. Another couple of pumps and it fell right through.

 

Now I need to figure out what I'm going to do with the weight and fix the shaft. As I figured, the weight has been drilled out to about a 1/2" diameter hole with no threads left. when someone could not get the set screw loose. Not sure what I will do with that. I may fill the hole by welding in a rod and drill and tap a new hole. I am also still toying with the idea of cutting it in half to make two weights out of it. The shaft has a place in it where they drilled into it that I will need to fill with weld and polish out.  

 

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1228180648-00.jpg


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#112 TOM KIEHL

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Posted 29 December 2018 - 04:37 PM

If it was I .......I would first make sure with a depth gauge that in fact the set screw IS gone .

 

2 . proceed with a soak of a penetrating fluid  of your choice .

3. remove OTA cradle , and Dec housing and bearings from cradle end of shafting .

4. Now all that remains is the bare shaft and stuck counter weight  .

5. sand rusty shaft (with Emery ) from counter weight face to toe saver end of shaft to a smooth rust free finish . 

6. Now place a piece of hard wood on the concrete  floor . Pick up and hold OTA cradle end of shaft vertical with stuck counter weight hanging downward over the piece of wood .

7. Impact wood block with varied force with counterweight shaft end ( The "Emery sanded end " ) . Lifting counterweight and shaft up and down to impact stationary wood block on the concrete floor . 

 

LET GRAVITY DO THE WORK........ Note : No parts are dented this way , like with a sledgehammer lol.gif

 

IF THIS PROCEDURE FAILS ........Get serious and take it to work and put it in a PRESS waytogo.gif lol.gif

" That's the way aha aha I like it " .....KC and the Sunshine Band band2.sml.gif

 

https://www.youtube....t=RDq3svW8PM_jc  

 

Great work Ken ! I knew you could git " Industrial " wit it  lol.gif .

 

Just got to love those Porta Powers

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Edited by TOM KIEHL, 29 December 2018 - 05:11 PM.

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#113 tim53

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Posted 29 December 2018 - 06:04 PM

Well that may be a while as it sure don't get cold like it used to be.

You'll probably be 10 feet under water and 50 miles offshore before cold becomes a serious issue again...   step.gif


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#114 Mr Magoo

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Posted 01 January 2019 - 09:03 PM

Got into the motor housing today. Lots of stuff going on in there. 

 

IMG_2148.JPG

 


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#115 Mr Magoo

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Posted 01 January 2019 - 09:04 PM

IMG_2149.JPG


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#116 Mr Magoo

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Posted 01 January 2019 - 09:04 PM

IMG_2150.JPG


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#117 Mr Magoo

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Posted 01 January 2019 - 09:05 PM

IMG_2153.JPG


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#118 Mr Magoo

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Posted 01 January 2019 - 09:06 PM

IMG_2154.JPG


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#119 Mr Magoo

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Posted 01 January 2019 - 09:08 PM

Looks like I have some demo work to do. A few extras that don't belong there. Not sure what was going on with that female plug. 


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#120 Mr Magoo

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Posted 21 April 2019 - 07:42 PM

Now that the weather is warming up I am hoping I can find some time to work on my Cave project. 

 

I'm starting from the ground up as I usually do. Stripping the legs and pier first. I did a little detective work to determine what the original paint scheme was. I carefully removed a few layers of newer paint and found the silver/pewter color at the bottom.

 

I also repaired the hole that was drilled into the dec shaft when someone was trying to remove the set screw in the counterweight. I filled in the hole with my TIG welder and some 309L filler rod. Polished it back down with a Dynafile and it came out great. Can't even see where it was. 

 

I worked on some disassembly of the mount. While trying to remove the RA shaft I discovered that one of the set screws in the clutch backing plate is split into three pieces so that will be fun to get out. It is also quite rusted. To that end I figured it would be easier to pull the shaft out with the plate attached to work on it. So now I need to do the cut down Allen wrench trick. Can someone tell me what the exact size Allen wrench is used there? It looks like maybe it is a 9/64".

 

Thanks!


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#121 DAVIDG

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Posted 21 April 2019 - 09:20 PM

 Hi Ken,

    Take all that  wiring and remove it and throw it in the trash ! That is not safe. Here is how I wired up a couple of Caves I have restored. Use a modern three prong grounded cord and ground the mount and install a fuse. 

   It looks like the gears and clutched have been " modified"  as well. Does the the 1 RPM motor still work ? Is the 10 tooth gear on the shaft of the motor still there ?  The gear on the shaft of the worm doesn't look original. They were usually made by Boston Gear and spoked. It should have 144 teeth.  So the drive is 1 rpm motor with 10 tooth gear that drive 144 tooth on the worm that drives a 100 tooth gear on the RA shaft.  The motor drives the worm at 1/14.4 rpm and that drive the RA shaft at 1 rev in 1440 minutes which is Solar rate. 

 

                - Dave

 

  cavewiring.jpg


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#122 Mr Magoo

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Posted 22 April 2019 - 04:44 AM

Thanks Dave. The wiring is a mess in there. I have already removed most of it. 

 

The drive is working. Accept for the piece of steel added across the top of the worm bracket, I think it came this way from Cave. The motor does have a 10 tooth gear on it and the other gear has 144 teeth. The 144 tooth gear is identical with the one on my RG. Just one more piece this scope has in common with the Meade. 

 

The last owner tried adding the ring of plastic in the clutch which is really a mess. I'm surprised it did not seize up everything and strip the motor. It will be gone. 

 

I am missing the little two button hand box for the Dec and will likely just make a new one. Can someone tell me the dimensions of what one of those is? 


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#123 DAVIDG

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Posted 22 April 2019 - 09:10 AM

Ken,

 I'm sure you know  all this. Another I thing I did was to use heavy duty springs on the three Allen head bolts that are used to adjust the tension on the clutch. Without the springs it was  difficult to find a tension on the bolts that had the right feel for the clutch. Either it was too loose and the  scope felt sloppy in RA or too tight. I also added a piece of thin gasket material as the friction surface vs metal on metal. Some sort of friction material is common in  almost all other clock drives vs the metal on metal that Cave was using. The friction material evens out the pressure and  gives a better feel when you move the scope. 

  The handle paddle was about 2" x 3". Since you have 120 volts  AC going up to it, I would make it out of plastic for safety  and any metal that might be used, ground that piece.  I used 4 conductor cable  so one of the leads was a ground and also used type of cable that to wire the Dec motor so the motor and the upper Dec assembly was grounded.  Be sure to fuse the  scope,  use a modern three prong polarized cord  and be sure to wire the Hot and a Neutral side of the cord correctly or the body the scope with be hot. 

 

                  - Dave 


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#124 Mr Magoo

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Posted 24 April 2019 - 06:55 PM

So after soaking the shattered Allen head set screw in PB Blaster for a couple of days, it came right out with a pair of needle nose pliers. I also cut down the Allen wrench for the collar and backed off those two set screws. For future reference, the size of the Allen wrench to cut down for my mount was 5/32". 

 

Now with all of the set screws backed off, the shaft will not budge. The clutch backing plate and the collar will not move either. I'm hesitant to put any pressure on the aluminum clutch plate for fear of warping it. Any suggestions on how to get things moving?



#125 Mr Magoo

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Posted 24 April 2019 - 09:25 PM

For the purpose of painting, I would at least like to remove the clutch back plate so I can remove the motor housing back plate. If I can do that, the shaft could stay in and be masked off. 


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