Tube rings and dovetail plates

[Mandopicker101]

Hello

I’m about to take the plunge and buy an AZ4 tripod and mount for a Celestron Powerseeker 80 OTA. The original EQ mount and tripod are shot but the tube is good. The mounting rings are a little odd in that they don’t attach to a dovetail plate but screw direct to the mount.

I’m thinking I can recycle the rings by screwing them into a dovetail. Will this work and should I opt for a longer plate?

[Louis D]

4 hours ago, Mandopicker101 said:

Hello

I’m about to take the plunge and buy an AZ4 tripod and mount for a Celestron Powerseeker 80 OTA. The original EQ mount and tripod are shot but the tube is good. The mounting rings are a little odd in that they don’t attach to a dovetail plate but screw direct to the mount.

I’m thinking I can recycle the rings by screwing them into a dovetail. Will this work and should I opt for a longer plate?

As long as the screws that held it to the mount are 1/4-20 (or possibly M6) sized, you should have no issues.  I recommend a long plate in case you use a 2" diagonal and 2" eyepieces or a 1.25" diagonal and a binoviewer.  That way, you can move the clamp point further back toward the focuser to attain forward-back balance.  If you only use a lightweight 1.25" diagonal with lightweight 1.25" eyepieces, you may not need an overly long dovetail plate.

You'll want socket head cap screws.  The length depends on the distance from the plate to threaded hole of the rings.  Surprisingly, this is not standardized.

[Mandopicker101]

On 16/05/2022 at 00:19, Louis D said:

As long as the screws that held it to the mount are 1/4-20 (or possibly M6) sized, you should have no issues.  I recommend a long plate in case you use a 2" diagonal and 2" eyepieces or a 1.25" diagonal and a binoviewer.  That way, you can move the clamp point further back toward the focuser to attain forward-back balance.  If you only use a lightweight 1.25" diagonal with lightweight 1.25" eyepieces, you may not need an overly long dovetail plate.

You'll want socket head cap screws.  The length depends on the distance from the plate to threaded hole of the rings.  Surprisingly, this is not standardized.

Thanks for some really good advice. I’ve ordered accordingly. As a bonus, the AZ4 mount includes a bracket for binoculars. I have a pair of Celestron Skymasters in need of a better mount.

[RT65CB-SWL]

Not very clear images, but the the threaded screw holes on my [SkyWatcher] 8"/21cm dovetail bar are 1/4-20 - [note: one is in the centre and one is offset from centre and hidden from view]. The larger ones at each end are not threaded. These are where fixing screws for the tube rings for a longer dovetail bar pass through to attach the tube rings. The reason I have used Jubilee/hose rings is because I cannot find tube rings that are the same diameter as the ETX105 tube... not very elegant, but it works! 

Link here for the SkyWatcher dovetail bars... https://www.firstlightoptics.com/sky-watcher-mount-accessories/skywatcher-dovetail-mounting-plates.html
or here for other brands... https://www.firstlightoptics.com/search/for/dovetail+bar/page/1/

Edited May 17, 2022 by Philip R

[Louis D]

A lot (but not all) dovetails also have threaded holes at the end to screw in safety capture (?) screws to prevent the dovetail from slipping out completely if the clamp is loosened accidentally.  The problem is, this then requires you to tip your dovetail into the clamp, which many clamps won't open far enough to allow you to do this.  I suppose you could just put one at the upper end and slide it in from the lower end.  This assumes your scope never nosedives while the clamp is loose.

[AstroMuni]

On 15/05/2022 at 19:51, Mandopicker101 said:

The mounting rings are a little odd in that they don’t attach to a dovetail plate but screw direct to the mount.

Do you have a picture? That would help us respond better

[Louis D]

@Mandopicker101Correct me if I'm wrong, but does your original scope and mount look like this at the rings?

[doublevodka]

If it's like the above then you should be good, as mentioned get a longer dovetail bar if you can. It'll help with positioning and also stop the tube from flexing so much. I've got an old cheap achro with a dovetail bar screwed to the OTA and it takes ages to settle, not because of the mount, but because of the flex in the tube.

Also if it is on an EQ1 mount as above, you may be able to salvage and sell the counterweight and bar, I understand it's the right type for people doing the eq mod on AZ-GTI mounts, might help pay for the dovetail  

[AstroMuni]

@Louis DThe OP has said the rings screw into the OTA, so assuming its different

[Mandopicker101]

16 hours ago, Louis D said:

@Mandopicker101Correct me if I'm wrong, but does your original scope and mount look like this at the rings?

Exactly this. New kit arriving tomorrow or Friday!

[Louis D]

On 15/05/2022 at 13:51, Mandopicker101 said:

The original EQ mount and tripod are shot but the tube is good. The mounting rings are a little odd in that they don’t attach to a dovetail plate but screw direct to the mount.

 

8 hours ago, AstroMuni said:

@Louis DThe OP has said the rings screw into the OTA, so assuming its different

Nope, OP said the rings screw to the mount as highlighted above.

3 hours ago, Mandopicker101 said:

Exactly this. New kit arriving tomorrow or Friday!

Further, OP confirms that's the mount.

@Mandopicker101BTW, make sure to let us know how you get on with all your new kit.  It's good that you're breathing new life into an older scope.

[Mandopicker101]

So it’s delivery day. Scope mounted onto AZ4. The bar is…large but I’m thinking future upgrade and the difference from medium to large was minor. I had a bunch of M6 bolts from, er, mountain bike brake callipers. These fit perfectly. Rings went onto the dovetail fine.

A quick lunchtime spell with a solar filter showed the sun in great clarity and stability. Focus and the setup stops quivering quickly. So far so good…

I ought to have sprung for the steel tripod though…

 

[Pixies]

Looking good.

If you do decide to to go for a smaller bar, FLO's Astro Essentials small dovetail bar is useful, as it has a slot rather than individual holes and means you can adjust the gap between the rings as you see fit. It's still 18cm long, though. For balancing, you could loosen the rings and slide the scope rather than slide the dovetali bar in the mount.

Here's a quick question for readers (sorry to jump into your thread). Do people prefer to store the mount with rings attached, and place the scope into the rings. Or keep the rings/bar attached to the scope and place the whole thing into the mount?

[AstroMuni]

18 hours ago, Louis D said:

Nope, OP said the rings screw to the mount as highlighted above.

22 hours ago, Mandopicker101 said:

You are correct. Misread

[AstroMuni]

3 minutes ago, Pixies said:

Do people prefer to store the mount with rings attached, and place the scope into the rings. Or keep the rings/bar attached to the scope and place the whole thing into the mount?

Latter. Rings & bar remain attached to scope

[Louis D]

1 hour ago, AstroMuni said:

Latter. Rings & bar remain attached to scope

The bar also makes for a nice handle to lift the scope out of storage if it is stored in a tightly fitted, foam lined case.

[Louis D]

2 hours ago, Mandopicker101 said:

Focus and the setup stops quivering quickly. So far so good…

I ought to have sprung for the steel tripod though…

Try putting vibration suppression pads under each tripod foot to settle the vibrations more quickly if needed.

Be careful to avoid over tightening the clamp on the lower leg section.  One used tripod similar to yours I looked at had split the ring around the tube to where it wouldn't tighten at all, so the legs had to be used all the way retracted.

Edited May 19, 2022 by Louis D

[Mandopicker101]

5 hours ago, Louis D said:

Try putting vibration suppression pads under each tripod foot to settle the vibrations more quickly if needed.

Be careful to avoid over tightening the clamp on the lower leg section.  One used tripod similar to yours I looked at had split the ring around the tube to where it wouldn't tighten at all, so the legs had to be used all the way retracted.

Yes this is where the tripod with the cheapo EQ1 failed. Not making that mistake again…