My astronomy project:
EQ6 Mount, dismantling / rebuilding

Contents:

1. Introduction and Disassembling
2. Internal gearbox alternatives
3. Needed belt length, measurements
4. New timing belt and pulleys has arrived
5. Lids to worm gear adjusted
6. Lathe of 60 teeth pulley
7. Installing 60 teeth pulleys
8. RA and DEC shaft shims
9. Test installing timing belts and motors
10. Installing RA timing belt and motor
11. Installing DEC timing belt and RA shaft into chassi
12. Testing and adjusting
13. Power up and EQMOD gear ratio setup
14. Hang up the telescope, balancing and calibrating parking point
15. Fine adjusting RA and DEC worm gear play
16. Test of auto-guiding
17. Deep into the RA drift compensation
18. During work

Note:
I take no responsibility or liability for what are written here, you use the information on your own risk!

15, Fine adjusting RA and DEC worm gear play:

I'm playing around with the controls of EQMOD and move the telescope to different directions to test that it works and also let the grease move out in all corners. After a while I felt that the play in RA and DEC worm gears was a bit high, at least in some directions. I thought it's best to investigate it now when I 'm having the mount indoors. I also found the telescope flex a bit in its holders.

Before I start examine the play in the worm gears I adjust the axial play of the the worm drives shaft to be tight with no play. I must only have a play at one place at the same time. Later I loosen these axial play adjusters a bit.

Checking RA worm gear play:

The EQ6 mount is no wonder of precision. The worm gear are not fixed at the shaft with a conical mount, that can introduce some eccentricity. This cause the play of worm gear to be different in different directions. I can only adjust the play to zero in the direction where it has its minimal play.

Here I have moved the DEC shaft to point left, only rotate the RA axis. It's also here that I found that the RA worm gear play is very small, but I check the other directions first before I do any adjustments.

Moved the mount to upward position. Found a small play in the RA worm gear in this direction.

Moved the telescope to the right. Found some bigger play in this direction. Moved back to the left position where I had the minimal play and adjust the RA worm gear play to be zero. Maybe this cause problem later when the mount is outdoors in the cold.

To do this I had to loosen the four lid holder's screws (vertical arrows) and then adjust the slider with the two opposite Allen screws (horizontal arrows) to have the worm gear tighter.

Checking DEC worm gear play:

Did the same procedure for the DEC axis. Moved the telescope to point left. Very low play in DEC worm gear in this direction.

Moved the telescope to point upwards, very low play in DEC in this direction.

Moved the telescope to the right, also in this direction very low play. Not much difference in different directions. I adjusted the DEC worm gear play in this direction to be zero.

Adjusting the RA and DEC worm drive axial play:

Now I loosen the axial play adjuster, not much, only just before I can feel a play.

Searching for flex:

I can feel that there are not only the play in worm gears that cause problems. When grabbing the telescope and bend it I feel it flexes in RA direction. After some investigating I found part of the flex in the top dovetail saddle. I have had problem with this before, have to after tighten the three Allen screws, very hard without braking them apart.

I also found the the dovetail rail flex a bit in the upper screw mount. Tighten the upper screw in photo above hard.

Even the lower dovetail rail screw mount flex a little, tighten it harder. I also use this screw to hold the mounting bracket for the focuser driver and control panel.

I was almost to close this project and start using the equipment, but then I got an idea. Can I add a mechanical stop that let the telescope be in correct position in the dovetail top saddle, the position where it is in balance?

Looking in my boxes and found this big washer, almost exactly the dimension I need.

Replaced the 1/4" 20 mm bolt with a 25 mm bolt and installed the washer.

Perfect, so much easier for me when installing the telescope on the mount outdoors in the darkness, always in correct place.

After this the mount is very stable and more easy to handle, never been that good earlier. But for sure I have to loosen and open the play in the worm gears later when the mount is outdoors in the cold. I will now take a break here, must do some outdoors test on real objects to see how it behave.

I have started with the altitude adjusting problem. Now in the beginning I only collect information. You can follow it here: EQ6 Wedge rebuilding.

Wish me clear sky !