Yamaha YK-X Series User Manual page 108

CHAPTER 4 Adjustment
6) Remove the cover. (See Fig. 4-10.)
WARNING
If the ball screw comes off the Z-axis motor, the Z-axis drops causing a hazard-
ous situation. Always prop up the Z-axis with a support stand or the like.
7) Prop the spline or end effector with a support stand to prevent the Z-axis
from dropping.
8) Lift up the Z-axis lower end damper. If this is difficult, insert a screwdriver
between the damper and the holder, and pry up the damper. (See Fig. 4-11 (a).)
9) Put a mark to indicate the current flange position with respect to the motor
shaft. Fit the spanner (wrench) to the flat surfaces of the flange and loosen
the bolts. This allows the ball screw to rotate freely independent of the Z-axis
motor.
10) Rotate the flange with respect to the motor shaft. (See Fig. 4-11 (b).)
Rotating the flange 30 degrees changes the machine reference value by 33%.
The machine reference value decreases by rotating the flange clockwise as
viewed from top, while it increases by rotating the flange counterclockwise.
Determine the flange position based on the Z-axis machine reference value
you made a note of, so that the machine reference value is within 33 to 67%.
11) Tighten the bolts a little at a time in a diagonal pattern. The tightening torque
should be 2.0Nm (20kgfcm). The bolts can be inserted into 10 holes among
12 through-holes.
12) Go outside the safeguard enclosure.
13) Check that no one is inside the safeguard enclosure, and then turn on the
controller.
14) Perform the Z-axis absolute reset.
To perform the Z-axis absolute reset, see "3-3 Absolute reset procedures" in
Chapter 4.
After absolute reset is complete, check that the adjustment machine
reference value is within the tolerance range (33 and 67). If the adjustment
machine reference value is outside the tolerance range (33 to 67), then repeat
the procedure from 4) to readjust it.
4-28