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cave setting circles

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#1 chuck52

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Posted 08 December 2012 - 07:09 PM

I have a basic question.What is the difference if any between a magnusson setting circle and a cave setting circle? I have read about Magnusson circles in this forum before and was just curious as to the visual difference? Did Magnusson maybe supply Cave with setting circles during a certain time or were they an extra cost option?

#2 dgreyson

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Posted 08 December 2012 - 07:53 PM

I am no expert, but: Apparently Cave bought out Magnusson according to the Cave Astrola catalog I have. In my catalog, Magnusson setting circles are polished aluminum with black engraving on the numerals. I know some earlier caves have Brass circles and some later ones have black painted circles. My 12.5 Astrola has Magnusson Circles, although some idiot had used one to back up his hand drill at some time in the past. Lots of pits and one hole all the way through. I will likely grind them smooth and cut an aluminum circle out of some aluminum sheet to bond over the damage to hide it. Would be a lot less glaring than leaving the swiss cheese look it has going.

You could buy magnusson setting circles in several sizes from the Cave catalog if building your own Scope.

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#3 Datapanic

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Posted 08 December 2012 - 09:12 PM

There are slight visual differences - as you can see in this photo...

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#4 John Higbee

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Posted 08 December 2012 - 09:25 PM

Dan - are there any current sources for aluminum or brass setting circles? The bakelite circles on my Cave 12.5 are not in the best shape (the declination circle has a big chip out of it), and I'd like to upgrade if there are sources.

John

#5 chuck52

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Posted 08 December 2012 - 09:35 PM

The picture really helps.So the Magnusson circles had 3 different length scribed lines for every 10,5 and 1 degree vs I guess it would be the standard circle with only 2 different length lines.Interesting.
Thank you for the help dgreyson and Dan.Now Im going to go look at the circles on my Caves.Im on a big learning curve when it comes to my Cave scopes.

#6 Datapanic

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Posted 08 December 2012 - 10:10 PM

John - I don't know of any source for setting circles like those, but a good machinist should be able to make them. This photo is the Maynard Clark's polished aluminum Dec Circle.

Chuck - I don't have a polished aluminum sample handy, but I know where there's an 8" f/6 lightweight deluxe with the grey paint scheme that has the 4" version of the circles.

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#7 tim53

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Posted 08 December 2012 - 10:21 PM

Dan - are there any current sources for aluminum or brass setting circles? The bakelite circles on my Cave 12.5 are not in the best shape (the declination circle has a big chip out of it), and I'd like to upgrade if there are sources.

John


John:

I have a few sets of black aluminum (I think) setting circles. I don't know if they were Caves, though. If you want, I'll double check these tomorrow and let you know what i have.

-Tim.

#8 Datapanic

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Posted 08 December 2012 - 10:53 PM

Personally, I think the Cave setting circles were one of the selling points of their line of scopes...

#9 John Higbee

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Posted 08 December 2012 - 11:55 PM

Tim - I am interested and would much appreciate your checking what you might have...my 12.5 has the standard 1 1/2" shafts.

thanks, John

#10 clintwhitman

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Posted 09 December 2012 - 03:26 AM

O Magnusson to my knowlage were never were owned by Tom Cave but Astrola did offer O Magnusson upgrade items with Cave Astrola Telescopes. O Magnusson built mounts and other very cool stuff. In 1975 I had an old junior Magnusson Mount for a while. I had a chance to talk to Oscar many years ago. He was old then. I think he is still alive and well into his 90s. :foreheadslap: CATALOG I still have a set of legs and one of their focusers around here somewhere. PS The entire family lives in Arvada, CO
Out of all the Telescope items I have managed to collect one of the items I like to see the most are the 6" Setting circles on the 65 Cave.. They are just to darn Cool! :roflmao: :roflmao:

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#11 Mirzam

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Posted 09 December 2012 - 07:19 AM

Parks has aluminum setting circles on their website. Don't know if they are really available though.

http://www.parksopti...Setting Circles

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#12 tim53

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Posted 09 December 2012 - 11:34 AM

Geez! $150 for a pair?? Gadzooks!

I paid nothing for the ones I have. They were given to me by Steve Eubanks a few years back. The RA circles might just be rings, though, as they were for a mount he marketed some time back.

-Tim.

#13 dgreyson

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Posted 09 December 2012 - 11:50 AM

JimC I put in an order for finder brackets to fix up my 12.5 cave from Parks a few months ago. The website took the order but never shipped. I called asking about them and a Lady answered the phone and told me that they were closed and that ScopeCity / Parks were undergoing re-orginization (bankrupcy) but that they hoped to reopen some day.
Im afraid they never will. Parks was the last place offering setting circles and other Cave compatible parts. everyone else is selling "Digital" setting circles now.

I have some sort of 1" shaft gem similar to Astrola/Parks ones with an 8" cradle that has no motor and no setting circles and was counting on getting a clock drive and a set of circles from Parks but I guess thats a vain hope now.

Thankfully, Rolando had a set of brackets he could sell me and I am able to proceed on my restoration on my 12" cave

#14 Don Hall

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Posted 09 December 2012 - 12:24 PM

John,
Are you still looking for the aluminum setting circles? I have a set of black aluminum (white numbers)purchased from Parks 2 years ago and never used. They are 6" diameter with 1-1/2" bore. PM if you are interested.
Don

#15 Datapanic

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Posted 09 December 2012 - 12:49 PM

If you want to turn a set of black anodized aluminum circles into polished aluminum, it's not too difficult. Easy-off Oven Cleaner will eat the anodized surface in about an hour, then a little wet sanding and polishing. This photo shows parts of the Maynard Clark scope from top to bottom, before, after and during.

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#16 JWW

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Posted 09 December 2012 - 12:54 PM

Geez! $150 for a pair?? Gadzooks!


FYI,

I wouldn't machine them for that price, regardless of the material (not that anyone asked).

-JWW:

#17 tim53

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Posted 09 December 2012 - 01:11 PM

I wouldn't either. Maybe I'm just incredulous that Steve gave me several sets for nothing.

-Tim.

#18 tim53

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Posted 09 December 2012 - 06:07 PM

Okay, so I didn't have quite what I thought I had. I only have two dec circles made of aluminum. One has a 1" hole and is black with white lettering. The other has a 1 1/2" hole and is bare aluminum with faint black lettering.

All the rest of the dec circles are molded delrin with scales attached to the outside edge. The stepped side with the set screw in it is machined, as is the outer edge, but the other side isn't finished. All the dec circles look to be 6" OD, with 1 1/2" bores. All the RA circles I have are also molded delrin with scales stuck on them. They're about 5 1/2" OD and have about a 4 1/2" bore. They were designed to be slip rings riding on a step in the worm gear, several of which I also got from Steve (but these are nothing like the Cave ring gear clock drives):

Here's one of the rings and the one aluminum dec circle I have with a 1 1/2" bore.

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#19 dgreyson

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Posted 10 December 2012 - 12:15 AM

Someone who was desperate could cut a plastic or wooden circle and insert it into the hoop ring to use it on a gem shaft, make it a bit large and sand it to fit snug and then glue and paint to hide it. Apparently, back in the day, one could buy adapters to size a bigger setting circle hole down for a smaller shaft.

#20 dgreyson

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Posted 10 December 2012 - 02:28 PM

O Magnusson to my knowlage were never were owned by Tom Cave but Astrola did offer O Magnusson upgrade items with Cave Astrola Telescopes.


I have no doubt youre right Clint! I had read this in the 73-74 Cave catalog and assumed they had. Cant beleive everything sales literature says

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#21 tim53

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Posted 10 December 2012 - 04:31 PM

That actually seems right. I don't know of anybody using those circles after Cave folded.

Cool, my 12.5" has the 10" circles on it. They're awesome!

-Tim.

#22 SteveNH

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Posted 10 December 2012 - 11:47 PM

Just for comparison, here are the circles on the Cave mount I bought in 1969 for my 8". (I know, it needs a little TLC.) These 6" ones look very much like the Magnussen circles, and are solid aluminum. They are precisely made, and work very well. I wish the RA circle rode on the worm gear though, as in Tim's. I've come to tape it to the housing during observing so it doesn't move while I'm on an object.

The RA cirlce:

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#23 SteveNH

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Posted 10 December 2012 - 11:48 PM

And here is the DEC circle:

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#24 dgreyson

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Posted 11 December 2012 - 08:16 AM


Is it not supposed to move in step with the polar axis when the clock motor is running? Or is it too loose and spinning? Mine have a teflon rod backed by a set screw so it can be tightened down but still be able to be adjusted against the friction holding it and then keep its new place.
May want to pull it off an have a look at that, someone may have greased it in error.

#25 clintwhitman

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Posted 11 December 2012 - 09:29 AM

D I read that before but after talking with Oscar back in the late 1970s he said he still sold some circles and other stuff and I guess that over road what I read. :confused:






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