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Comet Catcher Resurrection

3d printing Celestron
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#1 Daver_tn

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Posted 07 January 2022 - 07:01 PM

So I've been trying to get my old Comet Catcher back in action. My grandmother gave it to me back in the 80s and I definitely haven't taken the best care of it. I was a kid! It came to me with a camera tripod ergo pointing it at a target meant aiming about a mile below the target and tightening down the tripod then let it settle and it would be pretty close. So I picked up a used cheap GEM with some very stiff grease. When I tore it down I found that it had probably never been used with the slow motion controls because the factory blob of grease was still within the span of maybe 10 teeth on the gears. So I cleaned it up and greased everything with some modern super duper stuff. Works like butter now!

 

Having read, in another post, that Agena has a set of rings that fits the ol'Comet Catcher, I went to their site and of course they were out of stock. No certain timeline for restocking. So I did what anybody in their right mind would do and measured what I needed and drew up a set in Fusion360 and then printed it with my 3d printer. Now, if I were billing hourly for this, these would be some seriously expensive rings. I mean the print time alone was 14 hours! But that's part of the fun. With a little bit of felt, the rings fit nice and snug on the old orange tube! Nice! 

 

Next step is mounting a spotting scope. Or in my case a red dot finder scope. So I present to you all the question, where and how do I mount that? Do I actually drill some holes in the tube, or is there a location on the scope where this should be mounted? Also, eventually this will probably get a laser pointer. I picked up the celestron red dot kit which has numerous mounting options.

 

Let me know what you think. I'm looking forward to the next clear night when I get go out and learn how to polar align this thing and enjoy the view again. 

-Dave

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#2 TwitchyMcJoe

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Posted 08 January 2022 - 07:45 AM

I'm guessing you printed those rings to 100% infill? You could get away with 50% or less for your finderscope dovetail.

I've seen two solutions for the finderscope. One is essentially copying the Vixen R150S/Celestron SPC6. You would drill mounting holes or glue it on:

Vixen-SP-140SS-Celestron-Comet-Catcher.j

The other is mounting the finder on the tube rings, usually on auxiliary bolt on areas:

post-63063-0-36125700-1586015017.jpg
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#3 Daver_tn

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Posted 08 January 2022 - 08:00 PM

Twitchy, I can't remember what I settled on for infill. I've been using cubic subdivision and it's amazingly strong even at low percentages. I think I did 50% where the bolt and hinges are. Everywhere else just sees hoop stress which runs the same direction as the outer and inner walls of the print. Should be plenty strong. Not so much rigid though. I didn't print any screw holes at the top of the rings for a dovetail. I like that more than drilling my ota, so I may print those and glue them on.

Thanks for the images! Svbony has a nice simple dovetail that would work. Also their helical focuser was recommended on another thread, for finer focusing. 



#4 telesonic

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Posted 09 January 2022 - 10:34 PM

Dave,

 

Nice Comet Catcher! I have one, and it's a really fun scope, mine is the later model black tube version - bought it used here a few years back, and don't plan on getting rid of it. It's a long project for me.

 

So first up, about mounting a finderscope on one of these - you could go either way, like Joe's post says. Since your tube wasn't drilled for one of these brackets, if you go that way - you'd need to put a couple of holes in the tube (not for the faint of heart - but simple enough.) I don't think that I would trust adhesive tape for this sort of thing, but you could certainly try it.

 

In your case.... I'd err on the side of least destructive here. Best bet is a bar mounted on the top of the rings, I think.

 

As for finders - I have a Pinty green laser pointer that I use with most of my scopes, along with a few 50mm optical finderscopes and a RDF to use as well.... and I had to kind of devise my own solutions that would work with my particular things.

 

For example, here are a few pictures of some of my finder setups:

 

First is an RDF reflex finder mounted on a short Picatinny rail, which fits into a Vixen finder shoe base. This was from Scopestuff.

Second is the RDF with the Pinty green laser, mounted to a 45 degree offset quick remove base.

Third is my 50mm home built finderscope, and a short Picatinny rail mounted to the top of the finder rings for the laser, or red dot.

(note - this is more complicated, as I had to drill and tap the rings... and also make sure that both finders would align with the telescope.... if I change this to a different scope, I must re-align the finders... not hard, just not much fun... but I have the tools to do these things)

 

So.... perhaps get a long Picatinny rail and mount that to the top of your rings, seems to be a simple solution with alot of versatility.

 

20210606 201359

 
20210606 201437
 
50mm Finder Project
 
And yeah, I also have an SVbony helical focuser / Eyepiece holder on my CCC....  Thread is 36.4mm male FYI.
 
Cheers,
T


#5 Daver_tn

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Posted 10 January 2022 - 07:59 PM

Telesonic,

   Thanks for the info. I've been back and forth on the laser method. I think it's great, however I live under a fairly heavy flight path for planes on approach to Nashville International Airport. They're about 15 miles out from landing so coming in low. Obviously I wouldn't point it at the planes; but, I am a little concerned about worrying the pilots. I want them to be able to stay good and focused on landing and not worry about someone pointing lasers in their flight path. Technically it all seems legal as long as I'm not pointing at them, just me trying to be overly cautious. Now, when I'm at another site, laser for sure! 

   I just placed an order from scope stuff Saturday and didn't see that when I was looking through anything and everything! I think printing and gluing a rail mount onto the rings will be the solution for V1. If I come up with other stuff I may update the ring plans and add a mount location. 

   I took the CC out tonight to look at some things and she's still getting the job done. My LX 90 GPS on the other hand is acting up and seems no longer know where it is. I gotta look into firmware updates. I wish the dern audiostar hand controller had a battery in it to keep clock information.

 

-Dave




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