Im seeing a lot of flex and play in the Dec. axis under load.

I noticed the dec axis is always very stiff, I figured this is how the new ones are.

Tonight for the first time, after shining a flashlight onto the gap that separates the moving top part of the Dec. plate and the Dec. body, I can see a gap opens up on top and it sticks to the Dec. body on the bottom.

When I flip the mount, the opposite happens. The previously bottom side that was touching the Dec. body now opens up.

Basically, there is a bit of play in the axis. This is not the top plate that comes off but the actual dec axis.
The top plate is bolted on.


The OTA is a CDK14 with camera weighing 70lbs.

Photos attached showing the dec axis play:

After you flip the mount, the gap opens in the opposite direction:

I suspect this is the reason I was having a lot of trouble with unguided imaging. 

My models always had this characteristic and worse on one side (East) with a steady drift in the points error.

I went through 3 different telescopes and several focusers with all of them having pointing models that looked similar.

Any feedback would be great.

1. Is there something I can tighten?
2. More importantly, is there a risk of the telescope falling off?

Thanks,

Rouz

Also, with the scope off to one side, the dec clutches are almost impossible to loosen.

This indicates the dec bearing play allows the load to be transferred to the dec clutch knobs.

Is this a similar issue posted here with the RA axis of the 1600?


https://www.youtube.com/watch?v=9WVpiZHDGjY&t=137s

Hi Rouz

What you describe sounds like the tapered roller bearings that support the Dec axis are not properly seated. This is something that George or Howard would have to confirm, but if that is your problem then I expect that there should be an adjustment nut that you can tighten to get them to seat properly. If I had to guess, it is probably under the Declination top plate.

If you have never adjusted a tapered roller bearing before, it is not particularly difficult, but you want to avoid overtightening them. Your goal is to adjust them until they are fully seated and no more.

Unless you are comfortable working with mechanical assemblies, I suggest that you wait until you can talk to George or Howard to get specific instructions on how to get to the bearing adjustment nut.

Mike

Hi Mike,

That's good news, thank you for the reply. I suspected something needs tightening.
Shipping the mount from Canada and back is a major concern because of the cost and meaning I'll be out of commission for a while.

I'm typically very comfortable with mechanical parts, so if there are instructions I should be able to do it myself. I'm really tempted to take it apart but will wait for confirmation before I touch anything.

Thanks,


Rouz

Good luck with it Rouz

If you are able to do the adjustment yourself, it would be great if you could take some pictures of the procedure and post them on the forum.

Mike

Hi Roland,

Thank you for the reply.

I opened the top plate and tightened all the 8 bolts. They were pretty tight, got another 1/12 turn maybe. Did the same on the RA axis, it got a bit more,  1/6 turn each.

I did notice that when I loosen the clutches, the gap opens up more. So the clutch knobs are load bearing, didn't know that and would only finger tighten them.

So its fine to fully tighten the clutch knobs, I will try that with an Allen key.
Should they be lightly tightened or considerably?  (My knobs have those tiny spring loaded balls on the tips).

With the clutches that tight, will it still slip if it bumps into anything?



Thanks,

Rouz

--
Roland Christen
Astro-Physics

Ok, got it.
Will try that.

Thanks,

Rouz

• I tightened the 8 Dec and Ra bolts. they were pretty tight to begin with.
•  
• I then tightened the clutch knobs all the way down with an Allen key.
•  
• The gap on the dec axis no longer opened up and the Dec' plate was parallel  to the axis which is good news.
•  
• However, making a model (same points as before) showed the error to much worse.

I did change the camera configuration so the balance was off:

1. I'm not sure if the balance being off caused such a larger error? (will rebalance and try again)
2. Can I have overtightened the 8x bearing bolts?

--
Roland Christen
Astro-Physics

Thanks Roland for putting my mind at ease yet again!
No I just used a short Allen key and no Moose.

The model error getting worse was probably due to the poor valance then, its fine balanced now and I will wait for another clear night.

Glad we don't need a moose. If we did, given AP's culture, the company would start shipping a new moose with each mount.

I remember my old Losmandy single clutch knob needed a moose to tighten. And I though I was strong with my weightlifting training!

But I always thought hand tightening those delicate spring tipped AP clutch knobs was enough. Glad I got confirmation here.

--
Roland Christen
Astro-Physics