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Sears 6339-a refractor counterweight

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#1 hboswell

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Posted 03 February 2025 - 08:46 PM

I've been searching for a counterweight for my Sears 6339-a. That was the only thing missing when I got it a couple of years ago. I've tried to find the weight of the original, and I've seen 2.5 pounds, 3 pounds, and 3.5 pounds. Right now I'm using a 4 pound weight and that seems like too much, so if someone knows what it would have been in 1967 that would be great. (What would be even greater would be someone having one hanging around that they don't need!).

 

Thanks,

Harry



#2 YourNotSirius

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Posted 03 February 2025 - 09:39 PM

I think my old man picked up one of those this summer. I can check and if it is that model can at least weigh it for you. My thought is that once the weight is known it won't be hard to reproduce one to the point where no one could ever tell.

 

Q



#3 apfever

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Posted 04 February 2025 - 12:32 PM

Mine is an original 6339-A weight that came in the wood box with original Styrofoam weight holder.  It weighs 4.138 pounds with the set screw, 4.110 pounds without the set screw. 


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#4 deSitter

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Posted 04 February 2025 - 12:37 PM

Mine is an original 6339-A weight that came in the wood box with original Styrofoam weight holder.  It weighs 4.138 pounds with the set screw, 4.110 pounds without the set screw. 

So the set screw is 0.028 lbs right?

 

Not so fast. You have to account for the gravitational binding energy of screw and weight, using general relativity. Let's see...

 

0.028 lbs. Nevermind.

 

-drl



#5 hboswell

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Posted 04 February 2025 - 12:41 PM

Mine is an original 6339-A weight that came in the wood box with original Styrofoam weight holder. It weighs 4.138 pounds with the set screw, 4.110 pounds without the set screw.



#6 hboswell

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Posted 04 February 2025 - 12:42 PM

That’s heavier than I thought. So I guess I’ll stick with the 4 pound weight I found. Haven’t weighed the set screw though!

Now I need to find a lens cap..

Thanks!
Harry

#7 deSitter

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Posted 04 February 2025 - 12:58 PM

That’s heavier than I thought. So I guess I’ll stick with the 4 pound weight I found. Haven’t weighed the set screw though!

Now I need to find a lens cap..

Thanks!
Harry

The "garbage can lid" cap with a handle is very hard to find. Also the plastic plug for the other end, where the focuser attaches. 3D printer to the rescue!

 

-drl



#8 YourNotSirius

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Posted 04 February 2025 - 04:52 PM

I guess you have your answer. Now I don't have to go digging that thing out, measure the CW and put it all back into the box and put that way, again. LOL

 

Oh fudge! I just remembered that I DO need to drag it out because the old man says he needs to do something to it. Apparently some part was not up to snuff or something like that. DRAT!

 

 

Q


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#9 Senex Bibax

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Posted 05 February 2025 - 09:18 AM

I might have a suitable counterweight in my junk bin,  I sold my 6339-A a year or two ago, but I might have had a spare. I'll have a look.


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#10 Don W

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Posted 05 February 2025 - 11:17 AM

What’s the diameter of the weight shaft?



#11 hboswell

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Posted 05 February 2025 - 12:57 PM

What’s the diameter of the weight shaft?

I measure it as 5/8" or 16mm.

 

Harry



#12 hboswell

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Posted 05 February 2025 - 01:07 PM

Another question, this one about the 22mm Kellner that came with it. There appears to be something screwed into the barrel, is this part of the Kellner or something that was just screwed? It's not a filter, it has clear glass, but it's in pretty tight. (Photo attached)

 

Harry

Attached Thumbnails

  • Kellner_22_965.jpg


#13 Don W

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Posted 05 February 2025 - 02:11 PM

12mm or 1/2” would be standard. 

There is a chrome barrel missing from the eyepiece. Without it, you cannot attach it to the scope.

 

Here is a YouTube video of this scope made by David Trott who is a member here.

 

https://www.youtube....h?v=tUxG_h-JTgU


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#14 hboswell

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Posted 05 February 2025 - 02:20 PM

12mm or 1/2” would be standard. 

That is not a normal eyepiece. I t is meant to be screwed into something like a finder scope or microscope.

A 22mm Kellner was included with the 6339-a when it was sold, and I've seen it described as the pick of the litter among the included eyepieces. That's why I think it's something screwed into the eyepiece.

 

Harry



#15 Don W

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Posted 05 February 2025 - 02:27 PM

I did a google search for your scope and found a lot of info! 
 

You should try it!



#16 deSitter

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Posted 05 February 2025 - 02:33 PM

Another question, this one about the 22mm Kellner that came with it. There appears to be something screwed into the barrel, is this part of the Kellner or something that was just screwed? It's not a filter, it has clear glass, but it's in pretty tight. (Photo attached)

 

Harry

Barrel is missing. Chromed brass part.

 

-drl


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#17 apfever

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Posted 05 February 2025 - 03:11 PM

The weight shaft is 0.628" which would be 16mm. 

 

The 22mm K eyepiece is missing the barrel that screws onto the threads shown. There is a field lens in the eyepiece that is flush to the end of the upper part. Be careful about that big lens being exposed. There is no lens that goes into the missing lower barrel.  The missing barrel is not the same as on the other 4 stock eyepieces. The other eyepieces take an external thread on the lower barrel, the K 22mm takes an internal thread on the lower barrel. 

 

Do a search for the K22mm green eyepiece.

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Edited by apfever, 05 February 2025 - 03:14 PM.


#18 hboswell

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Posted 05 February 2025 - 03:16 PM

The weight shaft is 0.628" which would be 16mm. 

 

The 22mm K eyepiece is missing the barrel that screws onto the threads shown. There is a field lens in the eyepiece that is flush to the end of the upper part. Be careful about that big lens being exposed. There is no lens that goes into the missing lower barrel.  The missing barrel is not the same as on the other 4 stock eyepieces. The other eyepieces take an external thread on the lower barrel, the K 22mm takes an internal thread on the lower barrel. 

 

Do a search for the K22mm green eyepiece.

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OK! I did find that little barrel rattling around the case, never dreamed the Kellner would be that long! Thanks!

 

Harry


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#19 Senex Bibax

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Posted Today, 10:28 AM

I do have a spare counterweight, but it is heavier than what you are looking for.



#20 Don W

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Posted Today, 06:16 PM

After a bit of digging I found these two CWs with16mm bores:

 

cw1.jpg

 

The one on the left is 2# 2oz

The one on the right is about 3# 10oz




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