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Eyepiece Safety Undercuts - a Bad Idea From the Start

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#76 bbqediguana

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Posted 21 July 2019 - 12:23 PM

Be sure to patent it if you do. waytogo.gif

Two words...

 

DUCT TAPE

 

smile.gif

 

(Cause I went the Red Green school of Automotive / Home / Telescope / Mars Habitat repair!)



#77 TOMDEY

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Posted 21 July 2019 - 01:00 PM

LAST RESORT:

 

You can push the eyepiece in with a wheel-puller... and twist/pull it out with Channel Locks.

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#78 Ihtegla Sar

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Posted 21 July 2019 - 01:47 PM

I don't think I'm any more dexterous than average, I'm a guy with big hands and short, fat fingers. Typing on a virtual keyboard is a problem for me because my fingers are too big to cover just one key.

I think there's a number of factors but attitude is probably one that's relatively important.

Figuring out solutions, figuring out the best way to do something has been something I've been good at, whether it's getting a wrench on a bolt that can't be seen or working out a complicated experimental procedure in the laboratory, I seem to be good at optimizing repetitive tasks.

I'm not afraid to experiment, to think outside the box. Don points out that the real problem is not the undercuts, it's the combination of the compression rings with the undercuts. The obvious solution is to remove the compression ring and just use set screws. I have a collection of brass and nylon thumb screws for just that purpose. I wish aluminum thumb screws were readily available because they're the best.

And too, practice does help. I change eyepieces at lot and I observe a lot, an average year is 500-600 hours observing.

But I think patience and a positive attitude are factors. Consider the title of this thread. It could have have been:

"I'm FRUSTRATED with eyepiece undercuts, what are your tricks to make it easy?"

I think first step is removing any compression rings if they're part of the problem. For Shorty Barlow who has physical difficulties, I don't know if this would help. But getting past our frustration and trying to understand his specific issues could help him deal with them.

YMMV

Jon


So are you saying the real problem is compression rings? I must admit I'm not sure I see the need for those either. Scratches on eyepiece barrels don't affect performance. Maybe getting rid of the compression rings is the solution. Or copper tape. But I imagine the tape won't work well for tapered barrels.
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#79 Shorty Barlow

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Posted 21 July 2019 - 01:56 PM

Two words...

 

DUCT TAPE

 

smile.gif

 

(Cause I went the Red Green school of Automotive / Home / Telescope / Mars Habitat repair!)

I'm pretty sure duct tape's already patented lol.


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#80 Shorty Barlow

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Posted 21 July 2019 - 02:03 PM

I find that the compression rings in the visual backs of my refractors (see earlier post) aid rotating the focuser for me. With a compression ring I can loosen the screws slightly so that the diagonal nose can move freely but still have enough friction to put a grip on the nosepiece itself. 


Edited by Shorty Barlow, 21 July 2019 - 02:04 PM.

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#81 Starman1

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Posted 21 July 2019 - 03:10 PM

So are you saying the real problem is compression rings? I must admit I'm not sure I see the need for those either. Scratches on eyepiece barrels don't affect performance. Maybe getting rid of the compression rings is the solution. Or copper tape. But I imagine the tape won't work well for tapered barrels.

Correct.  Tape won't fill the groove if it is a conical taper.



#82 Starman1

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Posted 21 July 2019 - 03:12 PM

I agree. Just want to add that if nylon set screws are used, there are no worries about getting marks on the barrel.

And two 1/4" x 20tpi glass-filled nylon screws set 120° apart will easily hold a 3 lb eyepiece. 


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#83 Starman1

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Posted 21 July 2019 - 03:32 PM

A Paracorr Type 2 has 3 (!) lips inside its top that the bottom of the eyepiece barrel can run into on the way in, and the top of the brass split ring, not counting the opening itself (we always have that, no matter what kind of binding is used), so that is a minimum of 4 possible knocks on the way in.

And, the top of the eyepiece's undercut groove can hit the top opening of the Paracorr on the way in AND the brass split ring inside the top.

That makes 6 possible additional barriers to eyepiece entry in addition to the opening itself.

In my Paracorr, the two helical stabilizing screws (not the thumbscrew you loosen to turn the top) protrude INSIDE the Paracorr and create two more obstacles in entering the Paracorr with the eyepiece.

They don't touch the eyepiece after the eyepiece is inserted, but they can be hit by the eyepiece barrel on the way in.  All my eyepieces have little scratch marks on the bottom lips for that reason.

[I need to file these screws a tad shorter--I just keep forgetting to do so.]

 

The undercut groove on the eyepiece can catch on the bottom of the brass split ring and the top of the split ring groove as it is removed.

Does it often hang up?  Yes, all the time.  My eyepieces have bevels on the bottom lips of the retention grooves, and they STILL hang up when being removed.

Typically, I cannot pull the eyepiece straight out, but must wiggle it back and forth a few times to get it out, and sometimes it hangs up once or twice and the thumbscrew has to be loosened

another 1/4 turn to get the eyepiece past the brass split ring.  Removing the 1.25" Paracorr adapter sometimes takes a repetition of loosening of thumbscrews and wiggling to get it out of the Paracorr.

 

So, I got the idea of designing a non-rotating helical top for the Paracorr, with a completely smooth internal surface  It would be a one-off device, and cost about $6000, so that consideration is out.

Alternatively, the 3 lips inside the top the eyepiece hits could be rounded or beveled on their top edges, similar to how the opening of the Paracorr is now.

 

At least the bottom section is smooth and slides in and out of the focuser quite easily.


Edited by Starman1, 21 July 2019 - 03:36 PM.

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#84 Ihtegla Sar

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Posted 21 July 2019 - 04:26 PM


It's the extra loosening of screws that bugs me the most. I have a hard enough time telling left from right and clockwise from counter clockwise in the daylight due to Dyslexia, which is not something you can unlearn. Having to loosen multiple screws at odd angles in the dark and then having to figure out which of the screws is causing the problem and loosening (not tightening) that screw in the dark with out taking it all the way out takes me out of my otherwise medatative mood.

#85 Orion68

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Posted 21 July 2019 - 05:44 PM

Guess I've been lucky, no jamming of the brass ring in the undercut yet (knock on wood).

 

I have run into another issue where the brass ring gets hung up on the edge of the undercut and the eyepiece wants to rock a little even with the set screw quite tight. If I rotate the eyepiece by 90 degrees and try again that usually solves the problem. Annoying for sure.

 

My preference would be to have eyepieces with no undercut, but it wouldn't stop me from buying an eyepiece I really wanted.



#86 Starman1

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Posted 21 July 2019 - 06:34 PM

Guess I've been lucky, no jamming of the brass ring in the undercut yet (knock on wood).

 

I have run into another issue where the brass ring gets hung up on the edge of the undercut and the eyepiece wants to rock a little even with the set screw quite tight. If I rotate the eyepiece by 90 degrees and try again that usually solves the problem. Annoying for sure.

 

My preference would be to have eyepieces with no undercut, but it wouldn't stop me from buying an eyepiece I really wanted.

Cure for that is to make certain the screw presses exactly in the middle of the brass split ring.

Of course, the eyepiece could be non-round.



#87 Pezdragon

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Posted 21 July 2019 - 06:49 PM

Zero thumbscrews, zero problems from undercuts.

 

 

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#88 luxo II

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Posted 22 July 2019 - 07:52 AM

Just when I think I've seen it all... now there's a focusser design that is new :) is that a one-off or is it a commercial product ?

Edited by luxo II, 22 July 2019 - 08:06 AM.


#89 Starman1

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Posted 22 July 2019 - 08:46 AM

Just when I think I've seen it all... now there's a focusser design that is new smile.gif is that a one-off or is it a commercial product ?

The idea of a "sled" focuser, which moves the secondary and eyepiece back and forth, is not new, but dates back a long time.

Celestron had such a focuser on scopes in the '80s, and amateurs had used the idea on scopes decades before that.

The primary engineering problem is maintaining collimation as the sled moves back and forth.


Edited by Starman1, 22 July 2019 - 08:47 AM.


#90 Scott99

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Posted 22 July 2019 - 09:06 AM

Land ho!  check out the Tele Vue 2.5x Powermate

 

 

https://www.amazon.c...h/dp/B0039ZICAI

 

 

41UWQ8kZfhL._SX425_.jpg


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#91 TOMDEY

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Posted 22 July 2019 - 09:09 AM

Just when I think I've seen it all... now there's a focusser design that is new smile.gif is that a one-off or is it a commercial product ?

Yep... here's a motorized version of that on the JMI RB-16 Binoculars. The focusing finesse, using the console push-buttons while looking through the eyepieces... is very precise and ideally-ergonomic. >>>    Tom

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#92 Scott99

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Posted 22 July 2019 - 09:19 AM

Is it just me or does a smooth barrel present a more elegant solution than the picture above?  lol.gif lol.gif


Edited by Scott99, 22 July 2019 - 09:20 AM.

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#93 Jon Isaacs

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Posted 22 July 2019 - 09:25 AM



A Paracorr Type 2 has 3 (!) lips inside its top that the bottom of the eyepiece barrel can run into on the way in, and the top of the brass split ring, not counting the opening itself (we always have that, no matter what kind of binding is used), so that is a minimum of 4 possible knocks on the way in.

And, the top of the eyepiece's undercut groove can hit the top opening of the Paracorr on the way in AND the brass split ring inside the top.

That makes 6 possible additional barriers to eyepiece entry in addition to the opening itself.

In my Paracorr, the two helical stabilizing screws (not the thumbscrew you loosen to turn the top) protrude INSIDE the Paracorr and create two more obstacles in entering the Paracorr with the eyepiece.

They don't touch the eyepiece after the eyepiece is inserted, but they can be hit by the eyepiece barrel on the way in.  All my eyepieces have little scratch marks on the bottom lips for that reason.

[I need to file these screws a tad shorter--I just keep forgetting to do so.]

 

The undercut groove on the eyepiece can catch on the bottom of the brass split ring and the top of the split ring groove as it is removed.

Does it often hang up?  Yes, all the time.  My eyepieces have bevels on the bottom lips of the retention grooves, and they STILL hang up when being removed.

Typically, I cannot pull the eyepiece straight out, but must wiggle it back and forth a few times to get it out, and sometimes it hangs up once or twice and the thumbscrew has to be loosened

another 1/4 turn to get the eyepiece past the brass split ring.  Removing the 1.25" Paracorr adapter sometimes takes a repetition of loosening of thumbscrews and wiggling to get it out of the Paracorr.

 

So, I got the idea of designing a non-rotating helical top for the Paracorr, with a completely smooth internal surface  It would be a one-off device, and cost about $6000, so that consideration is out.

Alternatively, the 3 lips inside the top the eyepiece hits could be rounded or beveled on their top edges, similar to how the opening of the Paracorr is now.

 

At least the bottom section is smooth and slides in and out of the focuser quite easily.

 

I haven't experienced the difficulties you describe with the Paracorr 2. My eyepieces are nearly all TeleVue.

 

It's possible the reason is that, as previously mentioned, I've tossed the compression ring the very first night and have been using set screws ever since.

 

There is a little rattle as the eyepiece slides in and out but there's no hang ups.

 

I tested the nylon screws I'm using. One easily holds the 31 mm Nagler. If I pull hard with the Paracorr in one hand and the Nagler in the other, it will slip the length of the safety flat.

 

Jon



#94 csrlice12

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Posted 22 July 2019 - 09:26 AM

No, no, smooth barrels might cause all kinds of havoc....dogs sleeping with cats, clear skies, wives approvving astro purchases....


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#95 25585

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Posted 22 July 2019 - 09:29 AM

For me it's not the undercuts, it's the blasted compression ring craze that popped up a few decades ago.

 

The issue with undercuts is with compression rings, undercuts were invented and gained traction largely before compression rings.  Compression rings came about because people worried about their eyepiece barrels getting scratched.  So now I have issues inserting and removing eyepieces because most of the available eyepiece holders have those things.

 

I'm not opposed to the compression ring itself.  It's the groove in the holder required to hold the ring.  I can't count how many times I've struggled to get an eyepiece into the holder because it catches on the groove *while inserting*.   For some reason, for example, my Lunt 60mm is really difficult to get my no-undercut plossls into, and constantly frustrates me as it catches on the compression ring groove.

 

I don't care about scratches on my eyepiece barrels.  Heck, we observe in the dark, right? smile.gif  However, because some do, we have compression rings, and thus the double-whammy of eyepieces getting caught while inserting into a holder, as well as the undercuts catching on the way out.  

 

IMO, blame the compression ring craze, not the undercuts,  Set screws work just fine, but everybody seems to offer primarily compression rings these days, for what is arguably an aesthetics issue.

I like the non-fiddlyness of twistlocks. Thumb screws, even those with larger heads, can chafe skin and gloves. Those thin silver ones are cruel!

 

For 1.25" eyepieces, using a smoother barrel converter to 2" is one option - a Howie Glatter Parallizer or Clicklock. For 2" eyepieces, fewer in number but heaviest, keeping secure is more important than keeping centered.

 

But I worked for almost 40 years where standard equipment had to be used. Not ideal ergonomically for everyone, but we adapted, developed skills and drills to cope with often outdated and awkward (so cheap but rugged) kit and equipment. This undercut issue, I can understand for some, but needs thinking around rather than getting stressed over.



#96 Jeff Morgan

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Posted 22 July 2019 - 10:05 AM

I like the non-fiddlyness of twistlocks. Thumb screws, even those with larger heads, can chafe skin and gloves. Those thin silver ones are cruel!

 

For 1.25" eyepieces, using a smoother barrel converter to 2" is one option - a Howie Glatter Parallizer or Clicklock. For 2" eyepieces, fewer in number but heaviest, keeping secure is more important than keeping centered.

 

 

Yes the ClickLock is fast, secure, and should be fine for gloved hands. Maybe even boxing gloves lol.gif

 

Do the twistlock collets (like ClickLock) have the same centering property as the Parallizer?

 

If so, I have another surplus piece of astro gear. 



#97 Starman1

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Posted 22 July 2019 - 10:22 AM

Yes the ClickLock is fast, secure, and should be fine for gloved hands. Maybe even boxing gloves lol.gif

 

Do the twistlock collets (like ClickLock) have the same centering property as the Parallizer?

 

If so, I have another surplus piece of astro gear. 

The Parallizer has the unique design that shoves the eyepiece off center one way, but shoves the adapter the opposite direction when it is tightened down and guarantees registration parallel to the focuser.

It centers the eyepiece because of equal but opposite shoves.  Collimation tools and 1.25" eyepieces will be held in the center of the focuser. [2" eyepieces will not, however, in a typical focuser.]

 

The Twist lock adapters do definitely hold the eyepiece in the center of the adapter, but the outer surface of the adapters is a smooth cylinder and gets shoved off center by the thumbscrew that holds the adapter in place.

That's actually not a bad thing, since it means the 1.25" eyepiece will be exactly the same amount off-center that the 2" eyepieces will be.  And if the collimation tool(s) is used in such an adapter, you will be aligning to the center of the eyepieces instead of the center of the focuser.

 

Now, should you use a twist-lock adapter in a 2" Baader Click-lock, then both 2" and 1.25" eyepieces will be held in the center of the focuser or diagonal.  The Glatter Parallizer adapter is incompatible with Baader Click Locks, as it defeats the design.


Edited by Starman1, 22 July 2019 - 10:23 AM.

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#98 25585

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Posted 22 July 2019 - 10:46 AM

I have noticed both interchangeable size stems for the TV Apollo eyepiece have undercuts. If they have no optic inside, perhaps TV could make a smooth stem, at least in one size as an optional accessory.

 

https://www.widescre...-eyepieces.html



#99 Jeff Morgan

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Posted 22 July 2019 - 10:49 AM

Thanks!

 

I could have been a little more accurate in my terminology. Instead of "centering" (which other products like HoTech also do) I should have said "paralleling".

 

Sounds like I'd better hang on to the Parallizer.


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#100 25585

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Posted 22 July 2019 - 11:06 AM

The Parallizer has the unique design that shoves the eyepiece off center one way, but shoves the adapter the opposite direction when it is tightened down and guarantees registration parallel to the focuser.

It centers the eyepiece because of equal but opposite shoves.  Collimation tools and 1.25" eyepieces will be held in the center of the focuser. [2" eyepieces will not, however, in a typical focuser.]

 

The Twist lock adapters do definitely hold the eyepiece in the center of the adapter, but the outer surface of the adapters is a smooth cylinder and gets shoved off center by the thumbscrew that holds the adapter in place.

That's actually not a bad thing, since it means the 1.25" eyepiece will be exactly the same amount off-center that the 2" eyepieces will be.  And if the collimation tool(s) is used in such an adapter, you will be aligning to the center of the eyepieces instead of the center of the focuser.

 

Now, should you use a twist-lock adapter in a 2" Baader Click-lock, then both 2" and 1.25" eyepieces will be held in the center of the focuser or diagonal.  The Glatter Parallizer adapter is incompatible with Baader Click Locks, as it defeats the design.

Don, do you then recommend a Clicklock for collimating a Newtonian with a 2" HG laser & Tublug.




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