Altitude adjustment - EQM-35 Pro

[Denys]

Hello there,

I am trying to set up my very first mount, a Sky-watcher EQM-35 Pro. I assembled the mount and now I am trying to set the latitude to fit with the place where I live, which is around 21 degrees (southern hemisphere, if that matters...). However, I noticed that the mount does not go to positions lower than 32 degrees nor higher than 65 degrees... Anything beyond this range and the bolts become too stiff and stop turning completely... (I will try to add a picture to show how it looks like)

Now, I am not sure if I am doing something wrong, or maybe there is some sort of trick to take the mount to lower latitudes...

Has anyone faced this problem before on this mount or in any similar mount? Any help would be much appreciated!

 

[Peter Drew]

I don't know the answer but I would suggest removing both adjusting screws and then see if you can manually rock the head to 21 degrees or if there is something internally preventing full movement.       🤔

[Seelive]

According to the manual it should go down to 15'. Try removing the right hand screw (in you photo) completely and tilt the mount down by hand too see how low it will actually go. When aligning my polarscope, I was able to go a lot lower than 30' so that I could easily view through the polarscope with it being near horizontal (infact I had to remove the counterweight shaft so that it didn't hit the north tripod leg).

[Kryptic]

@Seelivebeat me to it - specs on here https://www.astroshop.eu/equatorial-with-goto/skywatcher-mount-eqm-35-pro-synscan-goto/p,57352#tab_bar_1_select say 15 to 65 degrees. Agree with taking right hand screw out completely. After that it's contact dealer \ Skywatcher

[Denys]

Just now, Peter Drew said:

I don't know the answer but I would suggest removing both adjusting screws and then see if you can manually rock the head to 21 degrees or if there is something internally preventing full movement.       🤔

Thanks for the suggestion Peter. Indeed, by removing both bolts, I can manually move it to lower angles. There is however a physical stop that prevents it from going higher than the 65 degrees.

[Peter Drew]

That sounds promising!  Next I would suggest that you manually set the mount to your latitude and then carefully replace the adjusting screws until they come into contact without disturbing the setting.       🙂

[Denys]

Thanks @Seelive and @Kryptic. Just removing the right bolt won't do, as the bolt on the left is completely stiff. If I remove both then I can indeed move it to 15 degrees. However, if I try to insert the bolts back again, they do not lock against each another... I can only lock them in position once the mount is back to 30 degrees or higher...

[Kryptic]

4 minutes ago, Denys said:

I can only lock them in position once the mount is back to 30 degrees or higher...

Clutching straws - are they both the same length?

[Denys]

Just now, Kryptic said:

Clutching straws - are they both the same length?

No. The one on the left of the image is shorter. Should they be the same length?

[Peter Drew]

That's odd,  the tab detail that is cast for adjustment purpose is internal so I would expect that the adjustment screws must contact it within the alignment limits.

[Kryptic]

2 minutes ago, Denys said:

No. The one on the left of the image is shorter. Should they be the same length?

Don't know if they should be the same. Try swapping them around perhaps? 

Edited November 19, 2020 by Kryptic

[Peter Drew]

Try swapping the adjuster screws.

[Seelive]

35 minutes ago, Denys said:

Thanks for the suggestion Peter. Indeed, by removing both bolts, I can manually move it to lower angles. There is however a physical stop that prevents it from going higher than the 65 degrees.

The design of the mount is not particularly optimised for latitude adjustment especially near the limits. Even at 53', unlike the azimuth screws, they do not appear to 'lock' against each other. I thought that it may be due to the screws being nylon tipped but I now suspect it may be due to bending of the screws (there are plenty of threads on here about replacement altitude screws for SW mounts).  I would suggest slacking off the right hand screw as far as possible, move the altitude by hand to just less than your latitude then adjust to the correct altitude by screwing the right hand screw back in. The left hand screw can then be screwed in as far as possible to 'lock' to position. When polar aligning using the polarscope, small adjustments of either screw are obvious but as I said, they never seem to solidly lock against each other as you would expect.

Edited November 19, 2020 by Seelive
Typo

[Seelive]

30 minutes ago, Denys said:

No. The one on the left of the image is shorter. Should they be the same length?

I hadn't seen this whilst I was typing my last reply.  As suggested by Peter, swap them around and see if that solves your problem (but still don't expect a 'solid' lock!)

[Denys]

Thank you guys. I tried to swap them but it didn't work.

I made a sketch that helped me understand what may be going on  ... I will upload it here, in case you want to share your thoughts as well.

If I remove the right bolt (bolts are shown in red), I should be able to turn the one on the left and move the altitude all the way to 15 degrees. However, it comes to a complete stop once it reaches 32 degrees and won't go any further... So I think that maybe the head is turning slightly off-axis (that would be the blue cylinder in the picture), in such a way that at 32 degrees the blue cylinder starts to bend the bolt on the left, and prevents me from taking it any further... If this is really what is going on, then I don't know how to solve lol

[Kryptic]

10 minutes ago, Denys said:

turn the one on the left and move the altitude all the way to 15 degrees

Yeah, but only if it's long enough (hence the swap suggestion). But if that binds up... http://skywatcher.com/contact/