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12.5" F6 Cave

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#26 starman876

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Posted 17 June 2019 - 07:50 AM

Welcome to the club!  John

 

attachicon.gif P1010055.JPG

these 12.5" caves are such impressive scopes when you see them up close.


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#27 65&Counting

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Posted 17 June 2019 - 10:17 AM

these 12.5" caves are such impressive scopes when you see them up close.

Thanks John - I couldn't agree more. Whether or not it's undermounted, or has any number of other flaws, I'm re-living the my being a kid I never had - and drooling over the Cave brouchure was the unreachable quest - no more! And now I get to play which is what retirement is all about - right?

 

Thanks for your enthusiasm and everyone else's - having a blast!!


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#28 rolo

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Posted 17 June 2019 - 10:27 AM

I felt the Cave mount had some issues so I put mine on a Parks Superior mount with 6.6" OpticCraft drive. Much more stable on the Parks. With a Mototrak V drive corrector I tried a little autoguiding with PHD and it did fine.

Attached Thumbnails

  • Cave 019-small.jpg
  • M1HAGRBLCAVEF6.jpg

Edited by rolo, 17 June 2019 - 10:27 AM.

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#29 apfever

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Posted 17 June 2019 - 11:13 AM

The trick to saddling-up a big heavy ota is to stand the tube up on end and line the saddle up with it without the counterweight on.  Then add counterweight and swing the scope up for use.

This is soooooo typical easy that it blows my mind it's not a standard common no brainer.  These big OTA can be easily set on almost anything, a couple of just half butt sawhorses, a couple of ladders, on end like Tim said if long enough, back of the pickup, side of the trailer, and then swing the saddle to the tube.  Have a little box at the right height you can set one end of the OTA on and then stand up.  The box could probably double as a seat. 


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#30 65&Counting

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Posted 17 June 2019 - 12:15 PM

I felt the Cave mount had some issues so I put mine on a Parks Superior mount with 6.6" OpticCraft drive. Much more stable on the Parks. With a Mototrak V drive corrector I tried a little autoguiding with PHD and it did fine.

Very nice! I'm hoping that somewhat confirms my theory that much of the mount wobbles is from the undersized drive/clutch. Great pix!

 

Can you drive control a synchronous motor or does it have to be a stepper?

 

Someone had mentioned my superstrength.... er.... physique in handling this guy. Ironically, I have to take daily steroids to control my autoimmune arthritis but they're not anabolic ;-) At 6'2" and 195# I can do things for 30min and then spend 4 hours in bed - kinda sucks being seriously ill but I've always had a joyful take on life & I do what I can get away with.

 

Didn't have much trouble lifting the (mirrorless) tube in place so long as the saddle was horizontal - a third arm would be helpful to keep the rings in place but being tall made it easier.

 

Thanks for all the responses! Great fun!


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#31 tim53

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Posted 17 June 2019 - 01:40 PM

Sadly, the mount is too light for a 12.5" OTA.  A lot of the flexure is from the whole scope being cantilevered out from the polar housing on that 1 1/2" shaft, with no thrust bearing surface to help support the weight (as with an Optical Craftsmen 1 1/2" shaft mount, for example). You can overcome some of the wobbliness by keeping it well balanced in RA and Dec.  The 8" lightweight Deluxe was also undermounted on a 1" shaft mount, but if balanced well it was a very good visual instrument.  Of course, a bigger drive gear will also help, but even then some of the wobble is due to twisting of the shaft (No jive, I verified this with a Meade 1" shaft mount when I worked there 40 years ago).

 

Even the 2 1/2" shaft mount is susceptible to wind while observing.  These big OTAs aren't just heavy, they've got a big sail area and thus leverage against the mount.

 

-Tim.


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#32 starman876

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Posted 17 June 2019 - 01:44 PM

This is soooooo typical easy that it blows my mind it's not a standard common no brainer.  These big OTA can be easily set on almost anything, a couple of just half butt sawhorses, a couple of ladders, on end like Tim said if long enough, back of the pickup, side of the trailer, and then swing the saddle to the tube.  Have a little box at the right height you can set one end of the OTA on and then stand up.  The box could probably double as a seat. 

That does seem like the smart way to do it.  Does seem like a no brainer.


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#33 starman876

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Posted 17 June 2019 - 01:47 PM

Sadly, the mount is too light for a 12.5" OTA.  A lot of the flexure is from the whole scope being cantilevered out from the polar housing on that 1 1/2" shaft, with no thrust bearing surface to help support the weight (as with an Optical Craftsmen 1 1/2" shaft mount, for example). You can overcome some of the wobbliness by keeping it well balanced in RA and Dec.  The 8" lightweight Deluxe was also undermounted on a 1" shaft mount, but if balanced well it was a very good visual instrument.  Of course, a bigger drive gear will also help, but even then some of the wobble is due to twisting of the shaft (No jive, I verified this with a Meade 1" shaft mount when I worked there 40 years ago).

 

Even the 2 1/2" shaft mount is susceptible to wind while observing.  These big OTAs aren't just heavy, they've got a big sail area and thus leverage against the mount.

 

-Tim.

balancing the scope is the first thing to do before I turn any motors on.  Always make sure the scope stays put in any direction I move it.   Guess these big tubes need a better aerodynamic design smirk.gif


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#34 CHASLX200

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Posted 17 June 2019 - 06:10 PM

Sadly, the mount is too light for a 12.5" OTA.  A lot of the flexure is from the whole scope being cantilevered out from the polar housing on that 1 1/2" shaft, with no thrust bearing surface to help support the weight (as with an Optical Craftsmen 1 1/2" shaft mount, for example). You can overcome some of the wobbliness by keeping it well balanced in RA and Dec.  The 8" lightweight Deluxe was also undermounted on a 1" shaft mount, but if balanced well it was a very good visual instrument.  Of course, a bigger drive gear will also help, but even then some of the wobble is due to twisting of the shaft (No jive, I verified this with a Meade 1" shaft mount when I worked there 40 years ago).

 

Even the 2 1/2" shaft mount is susceptible to wind while observing.  These big OTAs aren't just heavy, they've got a big sail area and thus leverage against the mount.

 

-Tim.

 

Sadly, the mount is too light for a 12.5" OTA.  A lot of the flexure is from the whole scope being cantilevered out from the polar housing on that 1 1/2" shaft, with no thrust bearing surface to help support the weight (as with an Optical Craftsmen 1 1/2" shaft mount, for example). You can overcome some of the wobbliness by keeping it well balanced in RA and Dec.  The 8" lightweight Deluxe was also undermounted on a 1" shaft mount, but if balanced well it was a very good visual instrument.  Of course, a bigger drive gear will also help, but even then some of the wobble is due to twisting of the shaft (No jive, I verified this with a Meade 1" shaft mount when I worked there 40 years ago).

 

Even the 2 1/2" shaft mount is susceptible to wind while observing.  These big OTAs aren't just heavy, they've got a big sail area and thus leverage against the mount.

 

-Tim.

They are bad in the wind for sure.  Just a 12.5" is too big for one person unless like your scope you can roll the whole deal out the door. My house is not set up for a scope like that.


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#35 AstroKerr

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Posted 17 June 2019 - 06:51 PM

oh, ya bastids; those are peachy. "Well-thought" and "properly executed" come to mind? What size those ring mounted finders?

 

I think that keeping the moments short and having sturdy infrastructure gives good results with any size shaft, but then larger diameter shafts generally mean less flexure, more inertia and thus shorter settling times, mount-wise yeah? Sail-like qualities of the solid tubes aside, they have less stray light. 

 

Nice scopes - very nice, gentlemen  bow.gif  waytogo.gif


Edited by AstroKerr, 17 June 2019 - 06:54 PM.

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#36 rolo

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Posted 17 June 2019 - 11:56 PM

Very nice! I'm hoping that somewhat confirms my theory that much of the mount wobbles is from the undersized drive/clutch. Great pix!

 

Can you drive control a synchronous motor or does it have to be a stepper?

 

Someone had mentioned my superstrength.... er.... physique in handling this guy. Ironically, I have to take daily steroids to control my autoimmune arthritis but they're not anabolic ;-) At 6'2" and 195# I can do things for 30min and then spend 4 hours in bed - kinda sucks being seriously ill but I've always had a joyful take on life & I do what I can get away with.

 

Didn't have much trouble lifting the (mirrorless) tube in place so long as the saddle was horizontal - a third arm would be helpful to keep the rings in place but being tall made it easier.

 

Thanks for all the responses! Great fun!

Yes the drive system is one of the main issues also the rear plate that the worm is bolted too is too thin.  If you look at the picture of my drive you can see the rear plate is 1/2" thick. Even with the Cave mount I enjoyed the heck out of the scope!


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#37 starman876

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Posted 18 June 2019 - 07:14 AM

Yes the drive system is one of the main issues also the rear plate that the worm is bolted too is too thin.  If you look at the picture of my drive you can see the rear plate is 1/2" thick. Even with the Cave mount I enjoyed the heck out of the scope!

Seems with a scope like that it would be hard not to enjoy using it.  I have enjoyed just about every scope I have ever used no matter what the issues might have been.  Telescopes are what we love.  Even in a cheap 60mm from Walmart we will find some enjoyment.


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#38 Dartguy

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Posted 18 June 2019 - 08:42 AM

Yes, the wheels make all the difference. I can wheel even this monster in and out of the garage by myself (Cave Transportable Observatory 12.5" f/7 on 2 1/2" shaft mount):

post-6788-14074265021826_thumb.jpg

Tim,

 

I like how you adjusted the mount so that it is polar aligned with the joint in the driveway.  I knew you were sharp, but nice thinking!

 

ps, that VW is awesome!


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#39 65&Counting

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Posted 18 June 2019 - 10:51 AM

To the many scope lovers here I agree completely - your first scope either ends in the closet or you continue.... on and on.

 

Bumps, warts, and all.

 

I'll always remember wanting something larger than my 60mm Sears Christmas scope and staring and the Edmund catalogues 4 1/4, 6, and 8" scopes around '68. The 6" was it.

 

I'd finally saved enough for the $199.95 small fortune then to get it - and was getting hammered by my mother about 'being sure I wanted it because that's all the money you have'.

 

So many doubts before it arrived - would I be unhappy? It came, I set it up, looked at a few terrestrial objects, and WOW. I was hooked. That night sealed the deal and never looked back. Best bang for the buck I'd ever gotten then and maybe to some extent even now - though it seems to have started all over again.

 

Still have that 6" and still love it.

 

I was always disappointed in shooting pix, commercial film processing, and tiny dissapointing images on 3.5 X 5 prints.

 

My dad knew a professional photographer who said he'd help me & spent several nights in the darkroom - opened up how photography/astrophotography (then) was done.

 

Bought an enlarger, chemicals, dyed a clear bulb red - and was blown away by what I could do with those small scale negatives in our single family bathroom with a towel thrown under the door - wow wow again! It started getting real. B&W was easy and fast.

 

The Star-Liner was next but I never really had time to enjoy it - life was in progress. But the Cave was the ultimate dream - even if hype outplayed reality. Just didn't matter to me.

 

And thoroughly enjoying everyone's comments! If I can't eliminate the wobble no matter Tim, Starman, and Rolo's enthusiasm is what I'm about - it's all good no matter what!


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#40 rolo

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Posted 19 June 2019 - 12:10 PM

This is soooooo typical easy that it blows my mind it's not a standard common no brainer.  These big OTA can be easily set on almost anything, a couple of just half butt sawhorses, a couple of ladders, on end like Tim said if long enough, back of the pickup, side of the trailer, and then swing the saddle to the tube.  Have a little box at the right height you can set one end of the OTA on and then stand up.  The box could probably double as a seat. 

The very few times I had to dismount the OTA I would point it straight up and lower it onto a tire with a piece of plywood on top. It was the perfect height.


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#41 starman876

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Posted 19 June 2019 - 12:52 PM

The very few times I had to dismount the OTA I would point it straight up and lower it onto a tire with a piece of plywood on top. It was the perfect height.

you got to use your brains to use a scope like this. Using brawn normally will be frustrating and very tiring.   Give me a place to stand and a lever long enough and I can move the world.  


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#42 John Higbee

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Posted 19 June 2019 - 05:09 PM

...and now a daylight view...

 

stacks_image_7341.jpg


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#43 starman876

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Posted 19 June 2019 - 05:17 PM

...and now a daylight view...

 

attachicon.gif stacks_image_7341.jpg

that scope looks even better in person waytogo.gif


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#44 CHASLX200

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Posted 19 June 2019 - 05:49 PM

This is soooooo typical easy that it blows my mind it's not a standard common no brainer.  These big OTA can be easily set on almost anything, a couple of just half butt sawhorses, a couple of ladders, on end like Tim said if long enough, back of the pickup, side of the trailer, and then swing the saddle to the tube.  Have a little box at the right height you can set one end of the OTA on and then stand up.  The box could probably double as a seat. 

Been there done that. Too much trouble when i was 27 and sure not doing it now at my age.



#45 65&Counting

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Posted 22 June 2019 - 02:09 PM

Dumbest question ever - how do the wheels/castors come out of the legs?

 

They're not screwed in - do you just give 'em a rap from the top to pop 'em out?

 

A larger wheel diameter would be nice - the stock ones are just too small - better than nothing but I suspect I can do better?



#46 CHASLX200

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Posted 22 June 2019 - 02:57 PM

Dumbest question ever - how do the wheels/castors come out of the legs?

 

They're not screwed in - do you just give 'em a rap from the top to pop 'em out?

 

A larger wheel diameter would be nice - the stock ones are just too small - better than nothing but I suspect I can do better?

They just pop out.  Could be stuck after many years of being in the legs.


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#47 rolo

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Posted 22 June 2019 - 03:18 PM

Dumbest question ever - how do the wheels/castors come out of the legs?

 

They're not screwed in - do you just give 'em a rap from the top to pop 'em out?

 

A larger wheel diameter would be nice - the stock ones are just too small - better than nothing but I suspect I can do better?

Larger casters are a great ideawaytogo.gif


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#48 starman876

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Posted 22 June 2019 - 03:54 PM

Dumbest question ever - how do the wheels/castors come out of the legs?

 

They're not screwed in - do you just give 'em a rap from the top to pop 'em out?

 

A larger wheel diameter would be nice - the stock ones are just too small - better than nothing but I suspect I can do better?

double wheels are even more fun.  The ones that are inflatable cannot be beat. 

 

https://www.casterco...spring-kingpin/

 

Makes a lot easier to roll the scope around.  



#49 65&Counting

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Posted 22 June 2019 - 04:24 PM

They just pop out.  Could be stuck after many years of being in the legs.

Perfect - thanks!

 

I bought a JMI Wheely thingy for a Meade Classic 12" LX200 with the upgraded (larger) screws and 5" hard rubber wheels - got hooked!

 

That sucker will go anywhere on any driveway surface short of gravel - and probably on some fine gravel with some heft - makes the Cave 'underwheeled'.

 

I debated the pneumatic tires but only for 1/10 sec - I've got 'em on dollys, yard tractor tires, etc. and am fed up with 'em. Everytime you need to use one is flat or nearly so.

 

Out comes the air pump! I can vouch for the 5" solid tires on the JMI - nothing could be better and no need for the handle - and what I'll be looking for the Cave.

 

If a larger pneumatic tire went flat on that magnificent beautiful glorius Cave I drove 15+ hours round trip to pick up and it tipped over..... devastation!!



#50 vjstangelo

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Posted 23 June 2019 - 09:28 AM

Does your tale sound like mine. I also purchased my 1st real telescope, a Meade 6” f/8, in high school. Very transportable and used for years until I picked up my 10” f/6 Starliner. It also is transportable, but not as much especially as I get older. Recently on a trip to NOLA I picked up a used Scopebuggy. I plan on wheeling it out of the basement when clear skies allow.

 

As our generation ages, I wonder what our kids will do with these classics when we pass on? I would bet that is how your Cave found its way on to eBay. 


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