Finder guiding issues with a Lodestar

[Ivor]

I'm struggling to get the RA axis back on, before I take the DEC section apart again can someone confirm whether the two copper bits for the RA and DEC are the same size?

Thanks

[MarkS]

Which copper bits?

Here's the rebuild guide:
http://www.astro-baby.com/EQ6%20rebuild%20guide/EQ6%20RA%20rebuild.htm

[Ivor]

The brass worm gear, section 5 picture 1

[MarkS]

I've no idea.  My guess is that they're identical, in order to keep down manufacturing costs.

I found it very tight to reassemble the RA axis - it is essential that the shaft goes in absolutely straight otherwise there is a risk the brass gear can jam against the walls of its housing.

So I put the taper bearing in first and then ensured the spindle went through the centre of the taper bearing as the mount base was installed onto the RA axis.  This ensures the spindle plus the brass gear go in perfectly straight. 

Mark

[Ivor]

Thanks, I thought the same. I took the same approach as you I just struggle to get it to go the last 1 cm and be flush with the worm housing.

I shall put the brass section in the freezer ( in a air tight container) for a bit and try again.

[Ivor]

I'm  still struggling to get the base back on the EQ6 I must be doing something silly but I just can't see what it is. I've checked the RA & DEC worm gear are identical so I'm at a lost as to why there is a depth discrepancy between the hole in the mount and the height in the worm gear. I can't see how you can put this together wrong so I'm perplexed as to why this has occurred.


RA worm gear depth


mount base depth


mount depth flush

Any thoughts?

[Rocket Pooch]

That looks a complete mess, how did the brass get that scored?

[MarkS]

The scoring is probably from the clutch mechanism so it shouldn't be a worry.

Have you got an RA Scale ring lying around somewhere? My guess is that you might be omitting it!  I would think that takes up most of the depth difference you are seeing.

Mark

[Ivor]

That looks a complete mess, how did the brass get that scored?

That just grease it cleans up nicely.

Have you got an RA Scale ring lying around somewhere? My guess is that you might be omitting it!  I would think that takes up most of the depth difference you are seeing.

Thanks, knew I forgetting something simple, I should stop trying to do this late at night but I want to look at Mars while there is a gap in the cloud.

[Ivor]

I've got the mount back together but not tighten everything up yet, it all moves smoothly and feels controlled not at all sloppy. If I put a 5kg counterweight on and from horizontal let go it will swing past the vertical once then return to the vertical and rest. Is this what I should expect?

[Ivor]

OK I've got there in the end, Graham at AstroTec was a great help lending me a homemade part to sort out a problem with the worm nut.

There is minimal backlash in Dec which I can't seem to tune out and in RA I've got the sloop down to <1mm but I get a strange clicking sound you can hear it in the video below at 10-11 secs and 24-30 secs.

http://vimeo.com/92186320

Any thoughts what it could be?

[Carole]

Is this the same problem as Fay's?  Also I think the link I posted up for Fay was this same guy for mending mounts.

Sorry I can't help Ivor, no good at this sort of thing.

Carole

[Ivor]

Well at long last I got to test my rebuilt mount, it is lovely and quiet in comparison to before except for one of the worm bearing which I commented on above. The mount appears to move smoothly however the RA axis is stiffer than before when the clutch is off which would make balancing the scope difficult if I didn't already know the right spot.

I guided whilst imaging M13, the log file can be accessed here https://drive.google.com/file/d/0B4aWTDNICIFvV1VLUHJMUTZadEU/edit?usp=sharing

I'd set the max duration 1000ms and during the two hours of imaging it hit that 109 times the larger subsequent adjustments push the average guiding up and I'm getting error 2 and 4 which appears to collates to a lower star mass but I can't find any reference to what they actually mean. There were a few clouds so I'm not sure it that is the problem.

Max pixel peak to peak error is 15.93, which is better than before but I'm not sure how to judge the overall guiding due to the errors and 1000ms issues. The image still have some elongation in the stars but it is better than before.





Another couple of nights is needed to tweak the parameters however I like to get to the bottom of the errors codes as well, I'm worried there is a problem with the camera.

[MarkS]

Unable to access the log files (from work).  Have you done one with the guiding switched off so the PE of the mount can be graphed?  I remember the previous one was very erratic (see graph earlier in this thread).

Error code 2 is where the S/N ratio of the guide star has dropped too far to be used.

Mark

[Ivor]

No not yet, that's part of the next session, it was just nice to image again I'd almost forgotten what I brought the telescope for. 

Any thoughts about the error 4?