Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Skywatcher's small equatorial wedge improvement solution

  • Please log in to reply
5 replies to this topic

#1 Fred76

Fred76

    Ranger 4

  • -----
  • topic starter
  • Posts: 350
  • Joined: 25 Nov 2008
  • Loc: Normandy, France

Posted 31 March 2020 - 08:05 AM

Hi all, with the Covid19 confinement, I had some time to look for solutions to improve the lightweight and cheap Skywatcher's small equatorial wedge I use with a Star Adventurer Mini. Some also use it with their Star Adventurer or alternative portable mounts.

 

The main weakness of this wedge is the altitude locking lever. There is quite a big gap between the altitude worm support and the flancs of the mount. When you lock the altitude lever, the Polaris moves sideways in the finder... and the polar alignment is quite difficult to adjust.

 

 image.png.63dabb1a22ea39f4c34930c2d7a108

 

 

I wrote a tutorial here, but it is in french. I will try to extract the main ideas below so that you will be able to improve the accuracy of this wedge. I tried to reduced the images to the minimum for the sake of your bandwidth.

 

Step 1 : unscrew completely the altitude lever :

 

image.png.ec168d1ba59a9f5aa55b672e4cd991

 

Step 2 : extract the axis screw and don't loose the small washer :

 

image.png.3baa3b9b119608b74b7dd90733fddeimage.png.67e41968dd7d68d90489e1be56a928image.png.a82998f1307df839682dbbf004d486

 

Step 3 : remove the altitude insert. There are two plastic washers. Just find some plastic sheet slightly thicker than those washers and cut a replacement washer from it, thick enough so that the gap is completely filled. Insert your new washer(s) and pieces back in place. It has to be quite difficult to put the washer, be patient ! If it is too easy, the gap is not filled enough. On my wedge, the washers were 0.50 and 0.25 mm thick (you may find other thicknesses), and I replaced the 0.25 mm one by a 0.60 mm cut from a plastic book cover.

 

image.png.6937e6c64fa699cd665a9d4c051be1image.png.226f7a88b819ab622da1cadbe54c5f

 

 

Now, on my Skywatcher equatorial wedge, the Polaris star doesn't swing sideway anymore when I tighten the altitude lever. Note that there is no need to overtighten this lever. Be gentle and it will last long !

 

 

Note : Be also very carefull with this small screw on the altitude knurled screw, it can unscrew by itself and if you loose it in the grass at night, you can go back home ! Use some thread lock to secure it :

image.png.d5ff4304cef11c8798c49196120dda


Edited by Fred76, 31 March 2020 - 08:31 AM.

  • eros312, Xeroid, cookjaiii and 1 other like this

#2 Shopaholic

Shopaholic

    Vostok 1

  • *****
  • Posts: 104
  • Joined: 10 Oct 2017
  • Loc: East Bay, California

Posted 03 April 2020 - 05:23 PM

Fred,  you are a genius, did the modification and there is no play and feels tight and moves smoothly. Will check later tonight and see how effective it is. Thanks!


  • Fred76 likes this

#3 Fred76

Fred76

    Ranger 4

  • -----
  • topic starter
  • Posts: 350
  • Joined: 25 Nov 2008
  • Loc: Normandy, France

Posted 04 April 2020 - 05:28 PM

Fred,  you are a genius, did the modification and there is no play and feels tight and moves smoothly. Will check later tonight and see how effective it is. Thanks!

Hi ! I'm happy that you're happy ! What is your feedback after testing ?


Edited by Fred76, 04 April 2020 - 05:29 PM.


#4 Fred76

Fred76

    Ranger 4

  • -----
  • topic starter
  • Posts: 350
  • Joined: 25 Nov 2008
  • Loc: Normandy, France

Posted 07 April 2020 - 08:01 AM

I present you another slight tuning that solves the problem of azimut setting inaccuracy.

 

Here is the original page (in french).

 

 

1) unscrew the two screws that hold the wedge to its base :

image.png.80dfaee916c53e2991bd01fd349e10

 

2) You will have access to the azimut setting pole, which will be loose over time, this is the problem :

image.png.9a9bec91e847ba5465ac1102d59225

 

3) Gently hold the steel pole with a plier and firmly tighten the x-screw

image.png.35cbfffc66c2e52f7217ca028d88a9

 

That's it, put everything back and you are done. Don't tighten the two screws of step 1) too much or the base will not be able to rotate...


Edited by Fred76, 07 April 2020 - 08:02 AM.


#5 Kevin_A

Kevin_A

    Ranger 4

  • *****
  • Posts: 323
  • Joined: 22 Aug 2018
  • Loc: Belmont, Ontario

Posted 07 April 2020 - 09:35 AM

I did all that awhile back and like you said... it greatly improves it. I also used vice grips and clamped my base slightly and carefully (as it is cast metal) as it was not parallel.. more open at the top as my shim would only go down half way. Once clamped and straightened i then used an additional thinner plastic washer (made from cutting a disk out of a clear plastic clamshell package) and its real tight now. Thanks for posting pics for everyone as people will appreciate your effort as it makes a big difference to this mount! I also adjusted the worm mesh by feel and sound to help with tracking and get around +/- 6 RMS now unguided and +/- 2 guided.



#6 Fred76

Fred76

    Ranger 4

  • -----
  • topic starter
  • Posts: 350
  • Joined: 25 Nov 2008
  • Loc: Normandy, France

Posted 22 April 2020 - 10:37 AM

 I also adjusted the worm mesh by feel and sound to help with tracking and get around +/- 6 RMS now unguided and +/- 2 guided.

How did you fine tuned the worm mesh ?




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics