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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!


10, Installing RA timing belt and motor:

Put on the grease:

EQ6 Mount, Installing timing belts and motors

This is the Lithium grease I bought, not white as usual.


RA shaft grease:

EQ6 Mount, Installing timing belts and motors

I put grease on the shims, RA shaft. Clean the surfaces very carefully before.


EQ6 Mount, Installing timing belts and motors

Grease on the worm gear. I cleaned the worm teeth very carefully before.


EQ6 Mount, Installing timing belts and motors

Grease on the worm drive.


EQ6 Mount, Installing timing belts and motors

I also dropped grease in the four holes that hold the RA lid.


EQ6 Mount, Installing timing belts and motors

I was not sure if I should have grease at the joint. But at last I put on the grease, it protect the surface from oxidation to some degree and maybe some water protection too.


EQ6 Mount, Installing timing belts and motors

Grease on the adjusting screws for the worm gear, one on the back side too.


Installing RA stepping motor:

EQ6 Mount, Installing timing belts and motors

The screws and washers for the bracket that holds the stepper motors.


EQ6 Mount, Installing timing belts and motors

After some work I got the motor in place. The belt drive can be seen through the opening. It will maybe be a problem how to find the correct tension for the timing belt.


DEC shaft, grease and shims:

EQ6 Mount, Installing timing belts and motors

DEC shaft, upper shims, worm gear, lower shims and scale. The DEC shaft is different, must be installed before the DEC motor and belt drive is installed.


EQ6 Mount, Installing timing belts and motors

The shims can sometimes "glue" together, especially the thin ones. Check that it's only one. Warning, the thin shims can be very sharp, don't cut your fingers !


EQ6 Mount, Installing timing belts and motors

The top shims is placed above the worm gear, tested out with try and error. I started with a 0.5 mm shim but had to add more later.


EQ6 Mount, Installing timing belts and motors

On top of this I place the DEC lid and then the worm gear. Then I place the lower shims, these I already have figure out what size, 0.6 mm, one 0.5 mm and one 0.1 mm.


EQ6 Mount, Installing timing belts and motors

Ready for a first test if I got the shims correct.


EQ6 Mount, Installing timing belts and motors

RA and DEC shaft assembled together.


EQ6 Mount, Installing timing belts and motors

Checking the clearance, 0.3 mm at worst place, little bit too much. But I have not tighten the tapered ball bearing at the other end yet. When I did that the scale was still a bit loose, but when rotating it it got stuck. It's not even, needs more space.


DEC shaft, shims try and error:

EQ6 Mount, Installing timing belts and motors

It was not easy to get out the old shims, used two small screw drivers. Maybe magnets had been better. Now I test with 0.3 mm shims (which was wrong).


DEC coupling lock screw:

EQ6 Mount, Installing timing belts and motors

Now I thought it will be correct and never had to open the mount again (but I was wrong). Then I must install the lock to the DEC coupling. The brass "washer" to the left can maybe be difficult to install afterwards, that's why it must be installed now.


EQ6 Mount, Installing timing belts and motors

You put in the washer from inside here. Put some grease on the brass worm gear where the clutch attach.


EQ6 Mount, Installing timing belts and motors

Put on grease on the same places as I did on the RA shaft, set some grease on the brass gear where the coupling's brake pad set in on the cylinder, hidden on the other side.


EQ6 Mount, Installing timing belts and motors

I found the best method to assembling them together was to let the DEC shaft stand up and then thread the RA shaft over it. Take it very slowly and do not use pressure, small small movements until they glide in place. Put on grease on the DEC shaft surfaces too where the roller bearing attach.


EQ6 Mount, Installing timing belts and motors

Don't forget to put back the lower shims once again, still 0.6 mm (in my case). Note: this is individual for every mount, you must measure it out for your own mount. It's wise to use rubber gloves, very greasy work.


EQ6 Mount, Installing timing belts and motors

Now the clearance has decreased to 0.1 mm.


DEC tapered ball bearing:

EQ6 Mount, Installing timing belts and motors

Before get the tapered ball bearing in place, clean very carefully and put on grease. Fill the tapered ball bearing with grease too.


EQ6 Mount, Installing timing belts and motors

The tapered ball bearing can be hard to get in place, be careful. After you had got it in place and have about 10 mm thread free, screw on the stop (the big white nut above) and use it to push the tapered ball bearing in place. If it resist something maybe is wrong, take it apart and look if something is in wrong position or bad.


DEC degree scale:

EQ6 Mount, Installing timing belts and motors

This time the scale got stuck. To small clearance. It feels like something is wrong.


EQ6 Mount, Installing timing belts and motors

Check the surfaces here if something is protruding. I have already before nailed it flatter.


EQ6 Mount, Installing timing belts and motors

Here I have found something that is not correct. When following the scale around there are some places where it's higher than the inner edge (ring).


EQ6 Mount, Installing timing belts and motors

I found that I had missed to clean it from dirt in the dig here and at other places.


EQ6 Mount, Installing timing belts and motors

Scratching it clean, I also removed some paint. Later I also noticed the the scale ring was not perfect flat. Couldn't do anything about that and it doesn't affect the function. I solved it by increasing the top shim to 0.4 mm.

My mount has always been very stiff, even when the clutches are free. I have always thought it was the grease that had aged. Maybe this paint and dirt was the problem. It could also be that the plastic shims that had been thinner under the pressure. A stiff mount is difficult to get in proper balance, when tracking these roller bearings are locked and the two others are in work.


EQ6 Mount, Installing timing belts and motors

Nice to see the mount a bit more assembled. Next time I can install the DEC motor and timing belt drive.

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