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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 chassis
  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. Drift align and auto guide calibration
  17. Setup EQMOD and PHD2 (moved to tutorial section)
  18. Test of auto-guiding
  19. Deep into the RA drift compensation
  20. Replacing the stepper motor driver
  21. During work

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


13, Power up and EQMOD gear ratio setup:

Installing RA and DEC clutch arms:

EQ6 Mount, Power up and EQMOD gear ratio setup

Now I need to use the clutches on the mount and I install the black arms to make the handling easier.


EQ6 Mount, Power up and EQMOD gear ratio setup

The backside of the arms, the star formed hole let you install the arm in different angles.


EQ6 Mount, Power up and EQMOD gear ratio setup

I set the arm to be in this position when clutch is open.


EQ6 Mount, Power up and EQMOD gear ratio setup

This is the closed position.


Installing driver board an cables:

EQ6 Mount, Power up and EQMOD gear ratio setup

The motor box with the three cables that shall be installed into the driver board.


EQ6 Mount, Power up and EQMOD gear ratio setup

Front panel to driver board. Note my special power cable, got tired on the connector that always jumped out. Soldered a permanent cable.


EQ6 Mount, Power up and EQMOD gear ratio setup

Backside with the PCB driver.


EQ6 Mount, Power up and EQMOD gear ratio setup

At the short side the connecters, RA, polar telescope LED and DEC.


EQ6 Mount, Power up and EQMOD gear ratio setup

Install the cables, don't mix them! The RA and the DEC connectors are of the same type.


EQ6 Mount, Power up and EQMOD gear ratio setup

Don't let the cables block the polar scope's opening.


EQ6 Mount, Power up and EQMOD gear ratio setup

Be careful when installing the panel to not squeeze any cable.


Power up:

EQ6 Mount, Power up and EQMOD gear ratio setup

Connect the serial cable with its 9 pin D-sub connector from the computer and power up.


Test DEC axis, 90 degree:

I do some small jumps with the RA and the DEC motor to verify that they work as they should. A bit more nosier than I thought, comes from the motor itself. I had to adjust the RA timing belt's tension, otherwise everything looks ok.

EQ6 Mount, Power up and EQMOD gear ratio setup

Set the DEC position to 90 degree or as close I can come.


EQ6 Mount, Power up and EQMOD gear ratio setup

Prepare for an 90 degree revolution on the DEC axis. Set the scale to 90 degree and locked it.


EQ6 Mount, Power up and EQMOD gear ratio setup

Move the DEC axis to 0 degree position.


EQ6 Mount, Power up and EQMOD gear ratio setup

Check on the scale where the DEC axis stop, at 4 degrees, not at zero as it should. That was expected because the gear box doesn't have the standard gear ratio anymore.


Setup EQMOD for a custom gear ratio:

EQ6 Mount, Power up and EQMOD gear ratio setup

I use CdC, Cartes du Ceil to control the mount through EQMOD. From CdC I can start the setup interface. Click on configure. Note the mount shall be disconnected.


EQ6 Mount, Power up and EQMOD gear ratio setup

Set "Show Advanced Options" and choose Custom from Mount options. Click the tool.


EQ6 Mount, Power up and EQMOD gear ratio setup

This is the menu where the gear ratio is setup.


Adjusting DEC axis:

We need some data to put in, this is an overview of the standrad data:

I need the figures for Total steps and Worm gear steps.

All EQ6 mounts has a worm gear of 180:1. The stepper motors has 200 steps per revolution and 64-bit micro steps. I have prepared a table to let it be easier to compare:

Type big wheel teeth small wheel teeth ratio RA gear ratio worm steps rev total steps rev
Spur gear 47 12 3.916666 705:1 50'133.33 9'024'000
Timing pulleys 60 16 3.75 675:1 48'000 8'640'000

As you see, no decimal, it's exact !

EQ6 Mount, Power up and EQMOD gear ratio setup

Here you can follow how I did the calculation of total micro steps per revolution.


EQ6 Mount, Power up and EQMOD gear ratio setup

To get the micro steps per worm gear revolution, just divide by 180.


EQ6 Mount, Power up and EQMOD gear ratio setup

Setup with these new figures.


Testing new setup:

EQ6 Mount, Power up and EQMOD gear ratio setup

This is the first time I setup a different gear ratio. Best to do a test. Move the DEC axis to 0 degree.


EQ6 Mount, Power up and EQMOD gear ratio setup

Set the DEC scale to 0 degree and lock.


EQ6 Mount, Power up and EQMOD gear ratio setup

Run the DEC axis to as close as possible to +/- 90 degree.


EQ6 Mount, Power up and EQMOD gear ratio setup

Read the DEC scale and check, yes correct.


EQ6 Mount, Power up and EQMOD gear ratio setup

Not much left to do now for a first outdoor test. I have noted some noises that maybe can cause a problem later. When moving the axis all the revolution round it in some places makes some oscillation sound, it sounds like the timing belt act as a string. But I don't think it have too high tension, more like the belt isn't perfect centered on the pulleys. Sorry to know there are so difficult to see what's going on inside.

Maybe the timing belt will rip off later, but now I must do some outdoor test before I take it apart again, if necessary. I could of course have made a new panel and mount the stepper motors on, let them have the pulleys on outside instead, much better overview.

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To page XIV, Hang up the telescope and calibrating parking point

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