Jump to content


Photo

Old SP-C8 Tube with an AVX mount?

  • Please log in to reply
15 replies to this topic

#1 wilki24

wilki24

    Lift Off

  • -----
  • Posts: 11
  • Joined: 07 May 2012

Posted 16 July 2014 - 04:32 PM

I've been digging around the forums for a couple of hours now, but I can't seem to figure out how I can attach my 1986-era Super Polaris C8 tube to a new Celestron Advanced VX mount.

Looking to how my C8 tube attaches to the SP, the dovetail bar is bolted on top of the mount, and the part that the dovetail slides into is mounted on the tube, which seems to be exactly the opposite of how the AVX seems to work.

Is there some way to do this?

Thanks!

Edit: Adding photo: http://i.imgur.com/P2Jsq66.png

#2 wilki24

wilki24

    Lift Off

  • -----
  • Posts: 11
  • Joined: 07 May 2012

Posted 16 July 2014 - 05:18 PM

After some more research, I'm looking at the options available here:

http://admaccessorie...uctgallery3.htm

The screws on the back of my C8 are 2.5 inches apart, and it's 12 inches from the centerline of those to the flat screw in the front.

I need to take this C8 apart and clean/align it anyhow, so I wouldn't mind drilling some holes, if necessary.

I'm just not sure what to buy at this point. Any help would be appreciated.

#3 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15697
  • Joined: 06 Jul 2007

Posted 16 July 2014 - 05:19 PM

There is no need to drill anything. A Vixen compatible dovetail will go right on. Before you take anything apart or drill anything, you might enlist the help of an experienced amateur from your local club. ;)

#4 wilki24

wilki24

    Lift Off

  • -----
  • Posts: 11
  • Joined: 07 May 2012

Posted 16 July 2014 - 05:53 PM

I assume you're referring to something like this:
http://admaccessorie...s_Dovetails.htm

However, my holes are 2.5" apart, but the product page says that the blocks have a hole spaces of 1.75".

I've found a few examples of people adding vixen dovetails to old C8 tubes, but none look like mine.

#5 jimbo728

jimbo728

    Mariner 2

  • -----
  • Posts: 246
  • Joined: 05 Nov 2013
  • Loc: Central NH

Posted 16 July 2014 - 07:22 PM

You need to remove all of the SPC8 mounting hardware. Your OTA will accept a Vixen dovetail right to the tube.You need not drill.
Jim

#6 wilki24

wilki24

    Lift Off

  • -----
  • Posts: 11
  • Joined: 07 May 2012

Posted 16 July 2014 - 08:21 PM

Ok, I took the old mounting hardware off, and there were no other holes underneath. However, rotating the scope a little I did find this set of bolts, which are exactly 1.75" apart in the back, with a corresponding bolt in front.

This looks like exactly what I need:
http://admaccessorie...s_Dovetails.htm

Back:
http://i.imgur.com/feQuqWe.png

Front:
http://i.imgur.com/qJHBXO9.png

Thanks everyone for the advice!

I've had this scope since I was 12 years old, and I'm very excited to finally have tracking capability with it.

#7 jrcrilly

jrcrilly

    Refractor wienie no more

  • *****
  • Administrators
  • Posts: 33887
  • Joined: 30 Apr 2003
  • Loc: NE Ohio

Posted 16 July 2014 - 08:27 PM

A less expensive way would be to buy a double-male Vixen plate from ADM or Losmandy (either is less expensive than a C8 dovetail) to mate the mount's saddle to the existing hardware on the OTA. The Losmandy version appears to have more "rise" to avoid any inreference with mount hardware.

#8 Nippon

Nippon

    Viking 1

  • *****
  • Posts: 975
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 20 July 2014 - 08:43 AM

I put a VC8 ADM dovetail on my old orange tube. It has threaded holes 1.75 apart on the rear cell and a single threaded hole on the front cell. The dovetail comes with radius blocks and hardware. I can use my old C8 on any mount that uses a Vixen style dovetail.

Attached Files



#9 jimbo728

jimbo728

    Mariner 2

  • -----
  • Posts: 246
  • Joined: 05 Nov 2013
  • Loc: Central NH

Posted 20 July 2014 - 02:24 PM

Nippon, Great set up.Your little buddy seems to like it too! Great shot! I have an old orange tube I might defork to ride an ASGT G5 mount.
Jim

#10 Nippon

Nippon

    Viking 1

  • *****
  • Posts: 975
  • Joined: 22 Oct 2009
  • Loc: Central Florida

Posted 20 July 2014 - 02:45 PM

I have the original fork mount and triangle lock tripod. The drive motors work fine and I love the looks of my OT C8 on the fork mount. But as far as enjoying an observing session the old fork can't compete at all with the AVX mount. It is so much steadier and you can actually observe stuff near the pole. Deforking the OTC8 was the best thing I ever did to it. Don't think my little buddy cares except perhaps she gets more pets during slews.

#11 Geo.

Geo.

    Mercury-Atlas

  • *****
  • Posts: 2954
  • Joined: 01 Oct 2008
  • Loc: Upstate NY

Posted 21 July 2014 - 05:05 PM

At the surface of the cell they are 1.75" on center. all C8s until the late 90s were drilled this way. Look at the holes at 12 o'clock they are 1.75 OC, too.

Attached Files



#12 rainman64

rainman64

    Sputnik

  • -----
  • Posts: 28
  • Joined: 02 Apr 2014

Posted 21 July 2014 - 08:36 PM

Will the ADM kit work on an Ultima 8?

I can't believe Celestron does not offer a vixen dovetail, for the older 8's.

#13 Geo.

Geo.

    Mercury-Atlas

  • *****
  • Posts: 2954
  • Joined: 01 Oct 2008
  • Loc: Upstate NY

Posted 22 July 2014 - 08:03 AM

Will the ADM kit work on an Ultima 8?

I can't believe Celestron does not offer a vixen dovetail, for the older 8's.


Well, they used to have a nicely made bar with flanges like their D bar. The rear screw holes were in the flanges. It had a steel wear strip to deal with the CG-5's clamping bolt. I've only seen one on an early G-8. Soon after that the OTA's intended for German mounts were specially drilled for the Synta bar and lost the fork mount trunion holes. Saw an ad for this type of bar at one of the UK sellers a few years ago.

The Ultima 8 has the same 1.75" mounting points as the earlier C8s, as does my Nexstar 8GPS OTA and my 1971 C8. Celestron has offered several accessories over the years that use these holes.

#14 jrcrilly

jrcrilly

    Refractor wienie no more

  • *****
  • Administrators
  • Posts: 33887
  • Joined: 30 Apr 2003
  • Loc: NE Ohio

Posted 22 July 2014 - 09:52 AM

Will the ADM kit work on an Ultima 8?


I just installed the ADM bar on my Ultima 8 outreach scope. No problems.

#15 rainman64

rainman64

    Sputnik

  • -----
  • Posts: 28
  • Joined: 02 Apr 2014

Posted 22 July 2014 - 10:19 AM

Thanks!
I just ordered it directly from ADM.
What was your turnaround time from your order?

#16 jrcrilly

jrcrilly

    Refractor wienie no more

  • *****
  • Administrators
  • Posts: 33887
  • Joined: 30 Apr 2003
  • Loc: NE Ohio

Posted 22 July 2014 - 10:31 AM

Thanks!
I just ordered it directly from ADM.
What was your turnaround time from your order?


He shipped right away and I had it in a few days. He's only a couple hundred miles away, though.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics