Balancing problem after hypertuning HEQ5

[Ishan Mair]

Hi.

I had noticed my HEQ5  RA axis was a little stiff. So I decided to open it up and fix it i.e. hypertune. In process I used sand paper on housing and the brass worm wheel cylinder. But once completed, I noticed a few problems which make balancing the mount a hell.

1) The mount (without CW and telescope) is significantly heavy to East side on RA axis due to two both motors being placed on that one side of axis. So much that I cant balance it. As a workaround I stick about 150 grams of weight to the West flat face of mount. Is it due to smoothness of RA axis? Did anyone else face this problem after hypertuning? I mean

2) The RA clutch lock is not able to hold against a little force.  I have tried adjusting the black clutch handle and the brass screw to no effect. Did I remove too much material with sand paper? Or is it the RA lock nut that needs adjustment?

3) I've tried putting cables through Velcro and giving them a loop and then attaching to tripod legs. But the cables, however I arrange them, always seem to drag the RA axis in some orientation or the other. E.g. if its balanced with scope pointing at the meridian, its not at all balanced when its pointing horizon on east. Often I see that if I hold a cable in my hand, the RA axis is stable. As soon as the cable rests on the RA axis, it moves a lot with some speed. If such little weight of cables can cause fast movement of RA axis, is the mount stable enough to do long exposure imaging? Or have I done something wrong in hypertuning?

All this makes me take about an hour to balance my mount. All this balancing is making me crazy !!

The irony is after all the balancing trouble, I have got decent (IMHO) 5 min subs with 650 mm focal length reflector with guiding.

Here's a PHD2 log file attached.

PHD2_GuideLog_2015-03-18_024622.txt.

..Please excuse the coma. 100% cropped from nearly the center.

Thanks,

Ishan.

[steppenwolf]

I can't comment on the success or otherwise of your 'hypertuning' but:-

1. it is completely normal that you can't balance without the counterweight bar and telescope installed so there is no problem there in comparison with a non-adjusted mount.

2. try the clutch operation again when you have the mount balanced with the CW bar, weight(s) and telescope.

3. it is important that ALL the cables are brought together to the centre of the mount at the junction of the RA and DEC axes - this will ensure the centre of gravity remains constant at all pointing directions. I note that you use a 130PDS - Newtonians make fine telescopes for imaging but for good balance, they should be orientated such that the focuser points in the direction of the mount i.e. with the mount in the Park position, the focuser should be pointed at the ground - this also helps to lower the amount of counterbalance weight required to achieve balance.

[Ishan Mair]

Thanks Steve.

But I thought if both the mount motors are placed on one side of RA shaft balancing can never overcome that as the mount itself is not symmetrical.

I checked the RA clutch with as good as balance, but it still gets free with a little bit of force.

I do follow the orientation you have suggested. Next time I setup, I want put cables through intersection of both the axes. But I am facing problems routing the cables. If you could show an image or two with examples of cable routing it would be easy for me to get some idea. 

Also, from the guide log, are there any indications of possible balance issues?

Ishan.