Mount Damage?

[Clarkey]

Due to my own idiocy, I managed to jam my HEQ5 against the door of my recently finished observatory. Seeing my guiding going to pot, I went and unjammed it after a few minutes, but the tracking now seems worse that it was previously. What I am wondering is, what have I damaged? Normally when adjusting the backlash, the motor whines, but in this case the mount was clicking. This makes me thing the gears were 'jumping'. If this is the case, I suspect I am likely to need a new worm and gear wheel in one or both axis.

I was wondering two things; Firstly, has anyone done anything similar and what damage was done? Secondly, if I do need new gear wheels, where is the best place to source them?

On another point - if you ever build an observatory make sure it has spring loaded doors.☹️

 

[NGC 1502]

When the door jammed on the EQ mount could it have been shifted away from polar alignment?  It wouldn’t take much to cause tracking errors.  You’ve said the mount was clicking. Is it possible that cogs have been moved out of line?  Can they be adjusted?

Hoping you sort it.

[tooth_dr]

I found my eq6 occasionally jammed up against the pier mid or end session, and on one occasion I found my 300p resting on a wall of the observatory at some point during the night. No ill effects noted.  Coming to stop at sidereal speed isn’t likely to cause any issues.  And the motors should stall, and wouldn’t have enough power to strip gears.  Does it manually move and feel ok?

Unless it was slewing when it jammed?  Or something got stuck and then twisted when you unjammed it?

On your other point - make a door that opens out 👍🏻

 

[Clarkey]

8 hours ago, tooth_dr said:

make a door that opens out

It did originally but it jammed the roof opening so I modified it. I had planned the design but for a number of reasons I had to make a number of modifications, this being one of them. Hindsight is a wonderful thing.

 

8 hours ago, NGC 1502 said:

polar alignment

Good point. I had to do a modification to a pier extension which is all held by the central bolt. So yes, it might have moved.

[Starflyer]

Steppers click when they stall, I doubt any damage has been done to the gears.

[Grant]

This is a pretty common occurrence and happens to all of us at some point or another - I think you would have to be quite unlucky to have done any serious or permanent damage!

[Clarkey]

I am following up on this post as my worst fears have been realised. Previously I could consistently guide to 0.6 - 0.7" rms and the mount was pretty stable when guiding - only minor corrections required. Now I am lucky if I can get close to 1" and more often 1.5" or worse. The mount motion is just so erratic. It guides ok for a while then seems to throw a complete wobbler and be all over the place. Since the 'incident' I have opened up the mount and checked for any (obvious) damage and can find none. This mount has just had new bearings throughout and a complete strip-down and rebuild. I have recalibrated and reduced the backlash as much as I can without binding and also done the usual guiding assistant etc.

So, the question is - does anyone know what might be causing this random behaviour? The only thing I can think of is that the worm drive has been very slightly bent - but that would be a consistent pattern, which this is not.

[markse68]

Did you change the worm bearings? They would take a lot of axial force when the mount jammed. Would click too if damaged

Mark

[LDW1]

If there is damage you are worried about why don't you show some photos of it ?

[1parsec]

The jam up may have moved the worm-wheel mesh and it might now be too tight  causing the bad tracking & guiding effects you're now seeing. 
You need the smallest amount of backlash (free play )in the mesh.

This explains the worm wheel adjustment procedure - https://www.astro-baby.com/EQ6 rebuild guide/EQ6 worm alignment.htm

 

[Clarkey]

9 hours ago, markse68 said:

Did you change the worm bearings? They would take a lot of axial force when the mount jammed. Would click too if damaged

Only prior to the jamming incident. Because I could not get metal bearings of the right size at the time, I used some ceramic ones. I'm not sure whether these are more susceptible to damage from lateral forces?

7 hours ago, LDW1 said:

If there is damage you are worried about why don't you show some photos of it ?

As I said above, there is no visual damage to photo. I took a screen print of the guiding trend last night to post on here, but for some reason when I came to paste it into the thread, it was no longer on the clipboard. In hindsight, I should have put the full logging on PHD2 so I could load the details. I do know the RA seems to be worse - but both axis are pretty bad. 

 

11 minutes ago, 1parsec said:

The jam up may have moved the worm-wheel mesh and it might now be too tight  causing the bad tracking & guiding effects you're now seeing. 
You need the smallest amount of backlash (free play )in the mesh

I've readjusted the backlash a number of times - both recently and many times in the past. I even took the belts off and drove the worm by hand to determine the point that it started to bind. From the backlash calculation it is about 500 milliseconds which is probably about 'normal' for an HEQ5 - or normal for mine.

 

[markse68]

“ ceramic bearings have load ratings 25 to 35 per cent lower than steel bearings. As the material is much harder, it is also more brittle. Therefore, when put under too much pressure, ceramic material may crack while steel is more likely to suffer indentations.”

that’s where I’d look

Mark

[david_taurus83]

When you say "jammed" do you mean it just tracked into the observatory? Or slewed or you moved it with force? I would be very surprised if it damaged any gears as it should just slip on its clutch. With the clutch tightened you should still be able to move the mount if you pull on the counterweight bar.

[newbie alert]

On 13/11/2022 at 22:54, Clarkey said:

Due to my own idiocy, I managed to jam my HEQ5 against the door of my recently finished observatory. Seeing my guiding going to pot, I went and unjammed it after a few minutes, but the tracking now seems worse that it was previously. What I am wondering is, what have I damaged? Normally when adjusting the backlash, the motor whines, but in this case the mount was clicking. This makes me thing the gears were 'jumping'. If this is the case, I suspect I am likely to need a new worm and gear wheel in one or both axis.

I was wondering two things; Firstly, has anyone done anything similar and what damage was done? Secondly, if I do need new gear wheels, where is the best place to source them?

On another point - if you ever build an observatory make sure it has spring loaded doors.☹️

 

I'd be quite surprised if you had damaged the worm or it's ring gear.. if it's clicking I'd fish out the gear, turn it by hand and you should hear it click if there's any damage.. then if it's not showing any signs of damage to check the worm or the bearings the only way is to take it apart... I'd be really surprised if they were

[Rob]

Sorry to hear this. If it were me I would re strip down, and swap those ceramic bearings out anyhow. I did my Heq5 this year and purchased the best I could for bearings. Mine had various issues.. including having to rubber mallet off the RA bearing. It was a horror show. Needless to say once all back together and set its now running like a dream. 
 

you will get to the bottom of it I’m sure!. Good luck.

Rob

[Craig a]

On 15/12/2022 at 11:00, Rob said:

Sorry to hear this. If it were me I would re strip down, and swap those ceramic bearings out anyhow. I did my Heq5 this year and purchased the best I could for bearings. Mine had various issues.. including having to rubber mallet off the RA bearing. It was a horror show. Needless to say once all back together and set its now running like a dream. 
 

you will get to the bottom of it I’m sure!. Good luck.

Rob

My neq6 had the rubber mallet treatment too for an hour 😂

But all is well once back together and tuned backlash it’s running great