TECHNICAL REFERENCE
471
June 1999
96-8000
SPINDLE ORIENT SWITCH
[Top rear of transmission]
Note: This switch does not exist on machines that have a Vector Drive.
A normally-open switch that is held closed is used to sense when the pin drops in to lock the spindle. When
the pin drops the switch opens, indicating orientation is complete.
The normally-closed side of the same switch that is held open, is wired to the spindle drive and commands it
into a "Coast Stop" condition. This is done to ensure the spindle motor is not powered when the pin is locking
the spindle.
X, Y, AND Z LIMIT SWITCHES
Prior to performing an POWER UP/RESTART or an AUTO ALL AXES operation, there are no travel limits.
Thus, you can jog into the hard stops in either direction for X, Y, or Z. After a ZERO RETURN has been per-
formed, the travel limits will operate unless an axis hits the limit switch. When the limit switch is hit, the zero
returned condition is reset and an AUTO ALL AXES must be done again. This is to ensure that if you hit the
limit switch, you can still move the servo back away from it.
The limit switches are normally closed. When a search for zero operation is being performed, the X, Y, and Z
axes will move towards the limit switch unless it is already active (open); then they will move away from the
switch until it closes again; then they will continue to move until the encoder Z channel is found. This position
is machine zero.
Auto search for zero in the Z-axis is followed by a rapid move from the limit switch position down to the tool
change position. This makes the Z-axis a little different from the other axes. The position found with the limit
switch is not machine zero but is the position used to pull tools out of the spindle. Machine zero for Z is below
this by Parameter 64. Be careful during the Z zero search and stay clear of that rapid move.
What Can Go Wrong With Limit Switches?
If the machine is operated without connector P5, a LOW LUBE and DOOR OPEN alarm will be generated. In
addition, the Home search will not stop at the limit switch and will instead run into the physical stops on each
axis.
If the switch is damaged and permanently open, the zero search for that axis will move in the negative direction
at about 0.5 in/min until it reaches the physical travel stops at the opposite end of travel.
If the switch is damaged and permanently closed, the zero search for that axis will move at about 10 in/min in
the positive direction until it reaches the physical stops.
If the switch opens or a wire breaks after the zero search completes, an alarm is generated, the servos are
turned off, and all motion stops. The control will operate as though the zero search was never performed. The
RESET can be used to turn servos on but you can jog that axis only slowly.
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