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Cave Carle Focuser

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#1 pcooper1960

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Posted 27 July 2020 - 12:25 PM

Hello All, I am a Cave Astrola owner of an 8" f/8 deluxe in fantastic shape. The original Carle focuser has a set screw can see in the picture attached. I use a small screw driver to change eyepieces and almost dropped it in the tube, yikes. Does anyone know the size and thread for the set screws so i can purchase a thumbscrew to replace it. I would take it to a local Lowes or Home Depot, but they are not enforcing masks:which is nuts!! Any help would be appreciated. Thanks and stay safe Phil

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#2 clamchip

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Posted 27 July 2020 - 12:57 PM

That set screw should have a spring loaded ball bearing in the end of it.

You can adjust it in or out to apply just the right pressure on your eyepiece

barrels.

As far as the thread pitch I'm not sure.

I remember replacing the set screw at one time with a nylon screw because

I could not find a metal one I liked the fit so I used nylon to prevent damaging

the thread.

It's finer than 32 per inch I remember that much, so more than likely metric.

I used the Carle focuser tube as a adapter, you can see it here, and the nylon

screw.

I sold the telescope.

Robert

 

post-50896-0-89914700-1415552141_thumb (1).jpg


Edited by clamchip, 27 July 2020 - 01:05 PM.


#3 Richard O'Neill

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Posted 27 July 2020 - 01:51 PM

I have that focuser on my 6" F/4 Cave. The screw used to secure the eyepiece is an 8-32.

 

Richard

 

PS. The original on my scope is brass but nylon secures equally well.


Edited by Richard O'Neill, 27 July 2020 - 01:55 PM.


#4 pcooper1960

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Posted 27 July 2020 - 02:31 PM

Thank you all, for your responses. That is interesting about the ball bearing and spring, I have to give mine a look.

 

Stay Safe and Clear Skies

 

Phil 



#5 tim53

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Posted 27 July 2020 - 04:49 PM

The ball and spring is in the larger setscrew toward the bottom in your first post.  You must be talking about the smaller set screw at the top.  I have several of these focusers, so I'll go look at what they have in them.  It's been a while.  But 8-32 makes sense, as the focusers and other Carle products are US made, so not likely metric.

 

-Tim.



#6 clamchip

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Posted 27 July 2020 - 05:10 PM

The ball-point set screw is finer than 32 per inch.

I measured it at 36TPI or .7mm with a OD of .1605"

A #8 screw is .164"

.1605" equals 4.076mm so it may be a 4mm  x .7mm

screw.

It's possible thru the years Carle couldn't fine the little

ball tip set screws in 8-32 and had to resort to metric. 

There's a larger one on the focuser body for rapid

traverse.

 

Robert


Edited by clamchip, 27 July 2020 - 05:22 PM.


#7 pcooper1960

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Posted 30 July 2020 - 02:13 PM

Thank you all for your responses. I did remove the set screw in the focuser barrel to take a better look and it is a neat little piece on engineering . It does have a spring load ball bearing at one end, the other end is tapered with a flat head screwdriver slot: and its stainless .

 

I thought I was repIacing just an old set screw, but I am going to "respect the design" on this one and I am going to keep it original. A lot of thought went into it. I will just have to be more careful with the screwdriver.

 

Thanks for any time spent looking into this for me.

 

Stay Safe

 

Phil

 




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