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eyepiece undercuts - SOLVED

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24 replies to this topic

#1 shams42

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Posted 02 August 2015 - 08:53 AM

Here is the cheap, easy, and quick remedy to the hated eyepiece undercuts -- Prostripe Pinstripes tape. You need the 1/4" width. I bought a 40 foot roll for roughly $4 at Advance Auto Parts.

The tape applies easily and is very forgiving. It can be peeled back and reapplied repeatedly. After a few hours it gets a bit harder to remove, but is still easily removable.

The tape provides a firm surface for compression rings to tighten against. I can report that it works very well! Prior to the tape, my eyepieces would sit loose in my Binotron-27. It drove me a crazy and affected the collimation of the images. After the tape, the eyepieces sit squarely and firmly.

If undercuts bother you, you might consider doing this. It only takes a few minutes, and if you don't like it, it's easy to remove before it dries.

Attached Thumbnails

  • IMG_2110.JPG
  • IMG_2111.JPG

Edited by shams42, 02 August 2015 - 05:01 PM.

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#2 starcanoe

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Posted 02 August 2015 - 09:07 AM

This is the greatest thing since they started selling socks three at a time!



#3 shams42

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Posted 02 August 2015 - 09:23 AM

Followup: it is easily removable even after 24 hours, but it may take a sharp hobby knife to get the seam to start lifting off without tearing. Once it starts coming off, it is super easy and does not leave a sticky residue.



#4 csrlice12

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Posted 02 August 2015 - 09:29 AM

I chalk up undercuts to man's ability to take any simple answer that works (plain barrels), and mess with it till it becomes completely unworkable to those who use it, then tell the world of their great accomplishment to the point that their peers shake their heads and say, "Oh yes, marvelous, lets do some more".........yet nobody bothers to listen to the end users...........

 

.......and truthfully, undercuts are on the low end of these "improvements" in all walks of life.....



#5 Arizona-Ken

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Posted 02 August 2015 - 11:04 AM

Followup: it is easily removable even after 24 hours, but it may take a sharp hobby knife to get the seam to start lifting off without tearing. Once it starts coming off, it is super easy and does not leave a sticky residue.

Important to know in case you want to sell your eyepieces later in good condition.

 

Arizona Ken



#6 Dubboy

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Posted 02 August 2015 - 12:21 PM

Thanks for the tip, shams42...

I'll stop at Advance Auto tomorrow when I'm in town...undercuts drive me nuts!! :mad:



#7 JIMZ7

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Posted 02 August 2015 - 12:49 PM

I always avoid buying eyepieces with "undercuts". I even dropped a eyepiece because it got caught up in the diagonal.

 

 

Jim



#8 Scanning4Comets

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Posted 02 August 2015 - 01:08 PM

I've been doing this since 2013. Great solution!

 

You can also use twist lock adapters, if you prefer to go in 2 inch mode. This also negates the undercut completely.

 

Here is a 2 inch extension tube with the undercut solved.

 

CS!


Edited by Scanning4Comets, 02 August 2015 - 01:10 PM.


#9 shams42

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Posted 02 August 2015 - 01:12 PM

Jim, I agree with this sentiment but in practice this would rule out many of the best eyepieces on the market.

 

Matt



#10 Michael Covington

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Posted 02 August 2015 - 01:22 PM

Not to mention the esthetic possibilities of pinstriping the telescope!

(Not as silly as it sounds.  It could be a quick way to make several pieces of equipment from different manufacturers look like they belong together.)

 

And maybe pinstripe could also be used like a parfocalizing ring -- run it around many times until it is at least 1 mm thick.  Back when there was such a thing, I used to do this with Dymo tape.



#11 Tank

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Posted 02 August 2015 - 01:42 PM

great job

just would like to mention another option is electrical tape you can find in the dolar store



#12 Scanning4Comets

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Posted 02 August 2015 - 01:54 PM

Not to mention the esthetic possibilities of pinstriping the telescope!

(Not as silly as it sounds.  It could be a quick way to make several pieces of equipment from different manufacturers look like they belong together.)

 

And maybe pinstripe could also be used like a parfocalizing ring -- run it around many times until it is at least 1 mm thick.  Back when there was such a thing, I used to do this with Dymo tape.

 

Rubber O-rings are a better choice for parfocal rings. Less time, less hassle, and easily put on / removed in one fell swoop.


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#13 junomike

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Posted 02 August 2015 - 03:43 PM

This is excellent as there's no cutting (length wise) required.

Definitely handy for BV users who experience merginging issues.

 

Mike


Edited by junomike, 02 August 2015 - 03:44 PM.


#14 RichA

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Posted 02 August 2015 - 05:41 PM

great job

just would like to mention another option is electrical tape you can find in the dolar store

Tape is ok as long as the diagonal uses a cinch brass ring to secure eyepieces.  If it just uses set screws, tape is likely not a great option.


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#15 Jeff Morgan

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Posted 02 August 2015 - 10:47 PM

 
 

Followup: it is easily removable even after 24 hours, but it may take a sharp hobby knife to get the seam to start lifting off without tearing. Once it starts coming off, it is super easy and does not leave a sticky residue.

 

Be extremely careful with that knife!

 

I have been using Trim-Brite tape (available in auto parts stores) to repair eyepieces with the undercut defect. I don't know if this solution is better or worse than the tape of this thread. But in time, tape solutions will exhibit wear and need to be replaced.

 

So, I took an X-acto knife to one of my eyepieces and discovered that the "hard" chrome finish of Tele Vue eyepieces is in fact very easy to scratch. One slip of the knife will cut a veritable canyon across the barrel of the eyepiece.

 

Better to take a cloth dampened in acetone and allow it to attack the glue on the tape. The tape substrate will then lift easily away.

 

Repaired Undercut Defect.jpg
 



#16 FirstSight

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Posted 03 August 2015 - 01:55 AM

I'm one of the very few nuts, not bothered by undercuts

But should one night, to my surprise I find

the undercuts are driving me, out of my mind

Thanks for showing me the way to escape, using some cheap pinstripe tape.

 

- Chris the starving poet


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#17 shams42

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Posted 03 August 2015 - 07:00 AM

Undercuts weren't a big issue for me until I got my Binotron. Undercut barrels will simply not be held securely by the self-centering diopters. Drove me nuts.

 

Hey Chris I don't know if you remember me - my name is Matt McBee - but we did a lot of observing together at Big Woods back in 2010. You showed me the Veil for the first time in your 12 inch scope.



#18 Lt 26

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Posted 03 August 2015 - 09:18 AM

My quick and simple fix for 1.25" under eyepieces is in the diagional. Remove the brass compression ring and fill gap with 3 layers of neatly trimmed electrical tape. Polish and round over set screw.

I have tried several fixes over the years. This is the best I have found yet. No worries about that brass ring getting unseated.

Dereck

#19 AJ

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Posted 03 August 2015 - 10:38 AM

Anybody have an idea how to "fix" Explore Scientific eyepieces' wide tapered undercut?



#20 junomike

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Posted 03 August 2015 - 12:16 PM

Anybody have an idea how to "fix" Explore Scientific eyepieces' wide tapered undercut?

The only sure way is to replace the barrel.  Gary had some  fabricated for the ES 24mm as well as 20mm I believe along with the Hyp Zoom.

Anothr CN'er used Al putty (or similar) to build up the surface but tthis involves grinding.

 

Mike



#21 Scanning4Comets

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Posted 03 August 2015 - 02:57 PM

Anybody have an idea how to "fix" Explore Scientific eyepieces' wide tapered undercut?

 

I used electrical tape around the tapered undercut. It is harder to get on there correctly because of the taper, but it can be done.

 

The leftover "goo" from the tape is easily removed with pure rubbing alcohol.



#22 JimMo

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Posted 03 August 2015 - 03:20 PM

I use Televue 2" extension barrels on all of my dual barreled eyepieces.  For some reason Televue didn't put undercuts in them.   :grin:   My 17 and 21 still have the undercuts but they are tapered and have never given me any problems.



#23 JayinUT

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Posted 03 August 2015 - 03:25 PM

Good thread with lots of good ideas. Thanks! 



#24 vkhastro1

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Posted 03 August 2015 - 04:14 PM

I only had the smooth barrel replacements made for the Baader Hyperion Zoom Mk III eyepiece.

A very successful undertaking with the new owners of the smooth barrel replacements being very pleased.

 

I did have another post to see if there was enough interest in fabricating smooth adapters for the ES 24 68* and ES

20/16 68* eyepieces ( a different adapter would be needed for the fore mentioned eyepieces ).

I did not receive enough interest to make it cost effective for the prospective purchasers.



#25 Lt 26

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Posted 03 August 2015 - 06:33 PM

That is what I like about the dual barrel Ehhos. Smooth barrel 1.25" and can be used as a 2" smooth barrel with extension or have your 2" undercut.


Dereck


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