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Cave restoration part 1 Revised

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#1 icomet

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Posted 05 December 2019 - 12:00 PM

Revised Post

 

Notice that set screw that's in the collar of the cradle. I loosened it, and the counter weight shaft slide right down on it's own. Luckily. it stopped after about 8".

 

 

That set screw in the image was all that was holding the counter weight shaft in place. This can't possibly be  correct. The counter weight shaft isn't treaded, or it doesn't have threads on the end that goes into the cradle.

There was no screw, bolt, etc. through the cradle into the  end of the shaft

 

Just trying to find out how the counter weight shaft is supposed to be held in place. 

When I picked the scope up, the cradle was rotated 90 deg. So I grabbed a hold of it and turned it, not seeing any locking mechanism for the shaft rotation. 

 

All this being said, I can't see how the shaft didn't slide down upon the turning of  cradle.

 

Hopefully, someone will chime in, for either it's obvious, and I'm not getting something, or the mount isn't finished correctly, or something.

Attached Thumbnails

  • cradle set screw.jpg

Edited by icomet, 05 December 2019 - 05:25 PM.


#2 CHASLX200

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Posted 05 December 2019 - 06:56 PM

All the Cave mounts i had had a big allen bolt in the center of the shaft that held it in place.



#3 icomet

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Posted 05 December 2019 - 07:39 PM

CHASLX200,

 

Thanks for your reply. I was thinking so, for there's a hole in the cradle, but the shaft isn't tapped/threaded for some reason.

 

Just wanted to hear from CN members. 

 

I'll have to get it drilled, and the little set screw at the opposite end of the housing, which is missing, and the thread size/fine/coarse-configuration is unidentifiable. I tried, that's probably why it's missing; I'll put a "shaft lock" bolt there to stop rotation.

 

I believe that's how my DS-16 mount is set up, except the  shaft lock doesn't contact the shaft, it squeezes the housing together just above the setting circle.

 

Clear Skies.



#4 CHASLX200

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Posted 06 December 2019 - 06:27 AM

Maybe someone replaced the shaft?



#5 apfever

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Posted 06 December 2019 - 08:40 AM

Hard time following this.  So the shaft slid down 8"??  There isn't 8" of cradle.  The shaft slid out of the saddle and went 8" down through the DEC housing of the mount and stopped before it dropped out of the mount?

 

The top of the saddle is solid except for a small bolt hole, so the shaft didn't slide through the saddle?

 

 

 

 

I'll have to get it drilled, and the little set screw at the opposite end of the housing, which is missing, and the thread size/fine/coarse-configuration is unidentifiable. I tried, that's probably why it's missing; I'll put a "shaft lock" bolt there to stop rotation.

 

 

What??  What set screw at the opposite end of the housing? Do you mean the set screw in the opposite end of the DEC shaft which would be for a toe guard bolt and washer? HUH? Put a bolt WHERE to stop rotation of what?  The saddle on the shaft or the shaft in the housing or???    The saddle is shown in the first picture, then there is the shaft that goes in it, and then the DEC housing of the mount that the shaft goes through.  I'd need pictures to be sure of what is being described.

 

The shaft is usually a snug fit into the saddle, if not a press fit or even a tighter heat shrink fit. The shaft will still work fine if it slips in and out of the saddle, as long as it is not distinctly sloppy and even sloppy CAN be anchored.  One simple thing to do is to make sure the shaft is tightly bottomed all the way into the saddle, then mark the location of that set screw hole.  One way to mark the hole is to run the set screw on and off a few times, or get an accurate pencil point in there.  Drill a hole in the shaft at the mark, so a longer set screw will anchor INTO the shaft. I would not bother with glue if a shaft is any form of press fit into a saddle, but if the shaft slips in the saddle then I'd add glue in addition to the set screw going into a drilled divot in the shaft. 

 

A bolt going THROUGH the top of the saddle and INTO  a threaded hole on the END of the shaft will certainly help hold the shaft into the saddle, but it provides minimal protection against the saddle rotating on the shaft.  You need that side screw shown in the first picture to anchor the saddle against rotation ON the shaft. 

 

Ideally, you would have a hole in each end of the shaft. One would be to bolt the shaft into the saddle and the other would be for a toe guard bolt and washer to protect against a weight accidently slipping off. My Caves haven't had toe guard systems but they are a good idea and worthy permanent mod to drill and tap into the shaft end. 

 

Please show a picture of any bolt missing in the DEC mount housing, that would be a shaft lock for DEC rotation. Perhaps a link to the previous thread on this scope?



#6 icomet

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Posted 06 December 2019 - 01:16 PM

<p>Here's some images of the shaft, both ends w/o threaded holes.&nbsp;</p>
<p>Images of the cradle with the hole for attachment to end&nbsp; of the shaft, I presume.</p>
<p>Image of the part of the housing that the c-wt shaft slides into with a small hole on</p>
<p>&nbsp; &nbsp;the other end opposite the cradle that didn't have a set screw in it.</p>
<p>&nbsp;</p>
<p>The c-wt shaft can slide with ease into the housing. Hence, when I removed the&nbsp; &nbsp; &nbsp;&nbsp;</p>
<p>cradle by only loosing that set screw on the collar, there was no center bolt, and can't be, no threads,</p>
<p>the shaft slid out of the housing.</p>
<p>&nbsp;</p>
<p>Having a&nbsp; &quot;keeper&quot; on the other end for the counter wt. is a good idea.&nbsp;</p>
<p>How about keeping the counter wt. shaft in place, a little better, referring to my situation.</p>

Attached Thumbnails

  • cave cradle 1.jpg
  • cave cradle 2.jpg
  • shaft 1.jpg
  • S 2.jpg


#7 icomet

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Posted 06 December 2019 - 01:19 PM

Sorry about the text in previous post.

 

Some  more images.

Attached Thumbnails

  • housing 2.jpg
  • housing 1.jpg


#8 apfever

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Posted 06 December 2019 - 05:06 PM

You already have a hole in the end of the shaft that goes into the saddle. That will make drilling a different size hole easier if you need to do so.  I'd drill the end of the shaft using the existing hole as a guide and then tap the hole for threads so it could be bolted into the saddle through that top hole in the middle of the saddle. The hole in the saddle is recessed so the head of a bolt won't interfere with the tube. See if you can determine if the paint is original and if it looks like a bolt was ever installed in that recessed hole in the saddle.  I would still drill at least a divot into the side of the shaft so the side set screw in the saddle has a solid imbed into the shaft. 

 

Thread the hole in the end of the shaft or drill and thread if needed, to accept a PRE CHOSEN bolt with a head that will recess into the hole in the middle of the saddle. 

Tighten that end bolt (after making one work) just enough to hold the shaft seated, and mark the side of the shaft for a divot to take the side set screw.

Put some glue on the assembly (NOT instant super glue) that will give at least a few minutes of work time. 

Insert the shaft into the saddle, line up that side set screw with the divot, and install both the side set screw and the end bolt.

Tighten both side screw and end bolt alternating, so they seat simultaneously. 

Tighten each till you think you might break something if you tighten more - then don't. (your comfort factor on this step)

 

I'm not so sure that hole in the DEC housing is for a shaft lock. It's not in a convenient location. It would typically be on the other side around the circumference. Any kind of set screw in that location would be asking for a bad galling into the shaft at a location that bears support around the shaft. I think there would be another form of locking the DEC motion. 


Edited by apfever, 06 December 2019 - 05:09 PM.


#9 icomet

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Posted 06 December 2019 - 05:25 PM

I'll take all into consideration. Thanks.

 

I appreciate the thought of the position of that set screw that is located in a weight bearing location.

 

What ever it was used for, it shouldn't be put in that location.

 

Thanks to all who replied.

 

I've got what I needed to hear to go  ahead a correct a couple of things.

 

Clear Skiess.


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#10 rolo

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Posted 07 December 2019 - 08:27 AM

Its possible that's not the original counterweight shaft and they didn't tap and thread the hole. Cave shafts were made of carbon stainless steel and would rust and pit. I replaced mine with better quality stainless. 


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#11 CHASLX200

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Posted 07 December 2019 - 08:36 AM

Its possible that's not the original counterweight shaft and they didn't tap and thread the hole. Cave shafts were made of carbon stainless steel and would rust and pit. I replaced mine with better quality stainless. 

That is what i was thinking. Never saw a set screw like that to hold a shaft on a Cave mount. Scary to think with the heavy weight added the shaft could come out and the OTA flops to the ground hitting one of the legs.


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#12 rolo

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Posted 07 December 2019 - 03:02 PM

That would be a disaster!




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