HEQ5 RA axis wobble

[matt_baker]

Always noticed on my HEQ5 Pro that the RA axis has a wobble even if I've dialled in the backlash as much as I could without it binding

Just wondering if anyone else has faced the same issue or know what the potential issue could be? 

It wouldn't bother me normally but I've noticed the guiding has been rather off on this axis. 

 

Matt

[michael8554]

In theory, RA is always being pushed in only one direction - slightly more, or slightly less, when guided.

So RA backlash will always be taken up.

Unlike Dec, which is guided in both directions, so Dec backlash routinely causes guide problems.

But I understand that belt-drive mounts should be "perfectly" balanced.

Which means in some positions the wind or cable drag could allow RA to "wobble" over the range of the backlash.

Whereas slight RA imbalance would prevent that.

Michael

[1parsec]

16 minutes ago, michael8554 said:

But I understand that belt-drive mounts should be "perfectly" balanced.

Michael

Rowan have never recommended that belt converted mounts should be perfectly balanced.  Not sure where this has arisen from.
Set a minimal RA East heavy imbalance to ensure the worm & worm gear clearance is working on the same side at all times.

The wobble in RA is a common issue (backlash in the worm gearing) but it may not be the reason for the guiding problems. 

Thanks, Dave.

 

 

[malc-c]

How are you detecting the wobble, and what is your definition of wobble.  Is it a spike in a PHD2 graph, is it regular such as a PE ?

 

[matt_baker]

I'm physically rocking it back and forth and it moves quite noticeably but not a ridiculous amount 

[david_taurus83]

You checked the end float play in the worm housing?

[malc-c]

If it's physically rocking then to me that sounds like a meshing issues with the gearing (worm).  End float as David has suggested and backlash adjustment should sort that out (I had a similar issue on my HEQ5 some years ago)

[matt_baker]

I've managed to fix it, last time I just wasn't patient enough with the tiny adjustments to get it almost spot on with the backlash