Content Preview
TB092 Rev2 Axis Home Too Close To Switch
Overview
This document describes how to correct the error message "_ axis home too close to switch "
Reason for message
In order for the unit to home to the same position at every startup the control moves the motor until it hits the
limit switch and then backs off the limit until it reaches an index pulse There is only one index pulse per
revolution of the motor If the index pulse is reached while the limit is still registering that it is tripped the motor
will keep turning until the limit is cleared and the index pulse is reached
If the index pulse comes immediately after the limit has cleared there is a possibility that during the next
homing sequence the limit will still be in tripped condition when that index pulse is reached This would cause
the home position to be one motor revolution off from the last home position thereby causing the part zero to
be off by that amount if the turns per inch is 10 then part zero will be off by approximately 100" The "_ axis
home too close to switch" error informs the operator that the home position is close enough to the limit switch
to possibly cause this situation
Adjusting the motor
By adjusting the motor the index pulse can be effectively moved further away from the limit switch to avoid
this message and more importantly allow a consistent return point for the homing sequence To adjust the
motor
1 Unbelt the motor
2 Rotate the shaft between 90 and 180 degrees
3 Re install the motor See technical bulletin #076
1 Be sure to follow guidelines for proper belt tension and pulley alignment
2 DO NOT impact the motor shaft or pulley in any way
Alternative Adjustment
The other option for adjustment moving the dog which trips the limit is not recommended because of the
possibility of moving the dog such that the motor is one revolution off from its previous state This would cause
the problem to not be resolved However if the dog is moved 05" and this does not cause the motor to hit the
hard stop the error will be corrected If this method is utilized the software travel limits will have to be reset
after the adjustment has been made
Z axis
If any of these adjustments are performed on the Z axis of an automatic tool change unit the
alignment for the tool carousel position will be affected and the G30 parameters will have to be reset
as outlined in technical bulletin #067
Document History
Rev2 Created on 2001 07 13
Rev1 Created on 2000 03 23