The easiest and most certain method of achieving alignment and smooth operation recognises that the tops of the screws float. This means that the constraints are the travelling arms (not adjustable) and the motor mounts (adjustable).
Try this
1) Release the four M6 screws fastening the motor bracket to the frame for each motor. The base of the lead screw is now adjustable in the X-Y plane.
2) Wind the lead screws through the nuts. Wind enough through so that the screw can be fully inserted into the coupler. Tighten the coupler capture screw.
3) Rotate the lead screws to move the travelling arms down to make light contact with the coupler. Move the motor mounts around to allow that travel to the point of contact. The motor and the lead screw nut are now aligned.
4) Wind the screws to move the travelling arms up and down 100 mm or so to confirm that travel is free and unrestricted.
5) Tighten the motor mount M6 screws.
6) Wind the arms up to the top (minimum z) to confirm that all is well.
February 4. Using a Moore and Wright Engineers Square to DIN 875 Grade 0 each of the twelve corner brackets in my kit were absolutely square - no daylight. They are good enough to do what is required of them here.
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The easiest and most certain method of achieving alignment and smooth operation recognises that the tops of the screws float. This means that the constraints are the travelling arms (not adjustable) and the motor mounts (adjustable).
Try this
1) Release the four M6 screws fastening the motor bracket to the frame for each motor. The base of the lead screw is now adjustable in the X-Y plane.
2) Wind the lead screws through the nuts. Wind enough through so that the screw can be fully inserted into the coupler. Tighten the coupler capture screw.
3) Rotate the lead screws to move the travelling arms down to make light contact with the coupler. Move the motor mounts around to allow that travel to the point of contact. The motor and the lead screw nut are now aligned.
4) Wind the screws to move the travelling arms up and down 100 mm or so to confirm that travel is free and unrestricted.
5) Tighten the motor mount M6 screws.
6) Wind the arms up to the top (minimum z) to confirm that all is well.
The grub screw is located at the end of the shaft/gear away from the motor body. The clearance between the gear and the motor body is 1 - 2 mm.
February 4. Using a Moore and Wright Engineers Square to DIN 875 Grade 0 each of the twelve corner brackets in my kit were absolutely square - no daylight. They are good enough to do what is required of them here.