How I dealt with the undercuts

[markse68]

41 minutes ago, Don Pensack said:

The amount the Parallizer is shoved sideways in the focuser matches the amount of sideways movement the other way by the thumbscrew in the Parallizer, so it is centered.

I wrote some illustrated instructions for the use of the Parallizer.

The Howie Glatter Parallizer.docx 75.4 kB · 1 download

it does cancel yes but doesn’t the precision depend entirely on tolerances of the different parts?

ps I’d argue that the 45deg clamping screw is more for applying clamping pressure in the middle of the barrel than for pushing the ep down- clamping at the top of the barrel has less mechanical advantage and the bottom of the ep barrel could lift off the parallelising ridges defeating the design. The outer parallelising edges don’t have that advantage of course though.

Mark

Edited August 28, 2021 by markse68

[JeremyS]

My war against the undercuts continues 

[JamesF]

1 minute ago, JeremyS said:

My war against the undercuts continues 

When the daily comics start printing stories about "Undercutgate", I'll know it's got really serious.

James

[JeremyS]

There we are: hopefully the nightmares are over 🤞🏻

All my 1.25-inch Tele Vues have rings installed. Takes a few seconds to attach each one.

Wish I’d done this before.

[Don Pensack]

Unfortunately, where you have positioned your rings means that in some focusers and adapters and star diagonals, the thumbscrews will press on the edge of the undercut and probably tip the eyepieces.

There is a cure for that, however: add barrel extenders to all the eyepieces and place the parfocalizing rings in the middle of the undercut.  You could keep all the eyepieces parfocal that way,

albeit at a somewhat inward movement of the focuser.

[JeremyS]

1 hour ago, Don Pensack said:

Unfortunately, where you have positioned your rings means that in some focusers and adapters and star diagonals, the thumbscrews will press on the edge of the undercut and probably tip the eyepieces.

There is a cure for that, however: add barrel extenders to all the eyepieces and place the parfocalizing rings in the middle of the undercut.  You could keep all the eyepieces parfocal that way,

albeit at a somewhat inward movement of the focuser.

Using them in the Tak prism diagonal. This has a compression ring. Seems fine. Best thing is I only need a small turn of the locking ring to engage the barrel (similar to what I need with EPs with no undercuts)

Edited August 28, 2021 by JeremyS

[Tiago Ferreira]

Different needs, different tools. For my fully 2" needs, APM Fastlock.

 

 

[Zermelo]

On 26/08/2021 at 20:41, JeremyS said:

Good luck John. At least they don’t contain any of that self vaporising and dissolving fluorite stuff 🤣👍🏻

"Your mission, Jim, should you choose to accept it, is to complete the Messier Marathon before dew sets in.
This objective will self-destruct in ten seconds ..."

(younger readers :- substitute a picture of Tom Cruise)

 

 

[johninderby]

And yoinger readers may not know what one of these is and the relavance to the above photo.. 😁

Edited August 31, 2021 by johninderby

[Louis D]

Found a good clip of the self-destructing tape for our younger contributors:

 

[John]

8 minutes ago, Louis D said:

Found a good clip of the self-destructing tape for our younger contributors:

 

Ohh, that takes me back !

 

[johninderby]

Errrr….what was this thread about? 😁

Good old SGL thread going off topic….love it.👍🏻

Edited August 31, 2021 by johninderby

[Deadlake]

14 minutes ago, johninderby said:

Good old SGL thread going off topic….love it

Have I got the correct url, this is not CN 😀

One solution is to buy Takahashi, APM,  Nikon or Baader (from memory). Then no pesky undercuts. 

 

[JamesF]

28 minutes ago, Louis D said:

our younger contributors

They're the ones who never really got on with watching this new-fangled television thing and just stuck with listening to the radiogram?

James