7.4.2 Zero Point at Positive Direction

Purpose: When zero point at positive direction, the positive pitch and negative pitch error's setting.

If for example Z axis zero point at positive direction, the distance is larger then 450 mm, can be split into 18 sectors, each sector length (screw pitch error compensation distance) 25 mm, each move would stop for 3 seconds, provide laser measurement time. While conducting compensation to the two terminals of the distance, there are over 2 mm distance that can be used to cancel backlash.

INCON-M84/M86/M86R with pitch error and negative pitch error example:

; (Zero Point at positive direction), please do manual homing first

; Sector Length= 25 mm, 18 sectors. (The traverse is larger than 450 mm)

; at each side terminal has 2 mm for eliminate backlash

;

; Main program

G90 G28 Z0 ; return to machine zero point

G91 G1 Z2. F2000 ; move backward -2 mm for eliminate backlash

G4 P1

G1 Z-2.

M97 P0001 L18 ; call subroutine 18 times

G91 G1 Z-2. ; move backward 2 mm for eliminate backlash

G4 P1

G1 Z2.

M97 P0002 L18 ; call subroutine 18 times

M30

;

; Second , third types of value combine to use movement sub program

O0001

G91 G1 Z-25. ; move backward -25 mm

G4 P3 ; every sector dwell 3 seconds

M99

;

O0002

G91 G1 Z25. ; move forward 25 mm

G4 P3 ; every sector dwell 3 seconds

M99

Because zero point at positive direction, measurement received value should be negative, the compensation value of each axis should be as following:

1.	Positive pitch measurement: start from home to travel - 450 mm's error value, please set "Machine Parameter → Pitch Error Table → Z Axis".

No.	CNC Controller Machine Position	Laser Detection Measured Position	Absolute Error Compensation Value	Incremental Error Compensation Value
0	0（Zero Point）	0	0	0
1	-25.000	-25.001	-1	-1
2	-50.000	-50.002	-2	-1
3	-75.000	-75.005	-5	-3
4	-100.000	-100.007	-7	-2
..	......	......	..	..
17	-425.000	-425.014	-14	..
18	-450.000	-450.015	-15	-1
19	..	..	0	0

2.	Negative pitch measurement: start from home to travel - 450 mm's error value, please set "Machine Parameter → Advanced → Reverse Pitch Error Table → Z Axis".

No.	CNC Controller Machine Position	Laser Detection Measured Position	Absolute Error Compensation Value	Incremental Error Compensation Value
0	0（Zero Point）	0	0	0
1	-25.000	-25.002	-2	-2
2	-50.000	-50.004	-4	-2
3	-75.000	-75.008	-8	-4
4	-100.000	-100.011	-11	-3
..	......	......	..	..
17	-425.000	-425.015	-15	..
18	-450.000	-450.017	-17	-2
19	..	..	0	0

When filling in pitch compensation table, must first fill in home position (in this example it is 18) then place in the compensation value from 18 moves forward (The 18's need fill in 0).

1. Use absolute error compensation value, fill in as following:

(1) Positive pitch error table - Z axis:

"Z Axis Pitch Error Table" Setting (User Absolute Error Compensation)

(2)	Reverse pitch error table - Z axis (sector length and zero point use pitch error table setting):

"Z Axis Reverse Pitch Error Table" Setting (User Absolute Error Compensation)

2. Use increment error compensation table filling as below:

(1) Positive pitch error table - Z axis:

"Z Axis Pitch Error Table" Setting (User Increment Error Compensation)

(2)	Reverse pitch error table - Z axis (sector length and zero point use pitch error table setting):

"Z Axis Reverse Pitch Error Table" Setting (User Increment Error Compensation)