I;m experiencing the same issue i.e. Z axis drops and ruins a piece and/or breaks a bit after changing a bit or running a new toolpath with the same bit after setting Z zero with a touchplate. I’m using Carveco Maker with the Grbl inch post processor and I see nowhere in the post processor a G28 command. I’m also using GSender with the Grbl firmware on my LongMill MK2. Limit switches are installed and are working properly.

The post processor is below:

;

; Grbl configuration file - with Arc Support

;

; History

;

; Who When What

; === ======== ========================================

; LA 02/03/20 Written

; LA 03/06/21 Added 4 dec places

;

DESCRIPTION = “Grbl (inch) (*.gcode)”

;

FILE_EXTENSION = “gcode”

;

UNITS = INCH

;

; Carriage return - line feed at end of each line

;

END_OF_LINE = “[13][10]”

;

; Block numbering

;

LINE_NUM_START = 0

LINE_NUM_INCREMENT = 10

LINE_NUM_MAXIMUM = 999999

;

; Set up default formatting for variables

;

; Line numbering

FORMAT = [N|@|N|1.0]

; Spindle Speed

FORMAT = [S|@|S|1.0]

; Feed Rate

FORMAT = [F|#|F|1.1]

; Tool moves in x,y and z

FORMAT = [X|#|X|1.4]

FORMAT = [Y|#|Y|1.4]

FORMAT = [Z|#|Z|1.4]

; Arc Centre Coordinates

FORMAT = [I|@|I|1.4]

FORMAT = [J|@|J|1.4]

; Home tool positions

FORMAT = [XH|@|X|1.4]

FORMAT = [YH|@|Y|1.4]

FORMAT = [ZH|@|Z|1.4]

;

; Set up program header

;

START = “T1”

START = “G17”

START = “G20”

START = “G90”

START = “G0[ZH]”

START = “G0[XH][YH]”

START = “[S]M3”

START = “G04P6”

;

; Program moves

;

RAPID_RATE_MOVE = “G0[Y][Z]”

;

FIRST_FEED_RATE_MOVE = “G1[Y][Z][F]”

FEED_RATE_MOVE = “[Y][Z]”

;

FIRST_CW_ARC_MOVE = “G2[Y][I][J][F]”

CW_ARC_MOVE = “G2[Y][I][J]”

;

FIRST_CCW_ARC_MOVE = “G3[Y][I][J][F]”

CCW_ARC_MOVE = “G3[Y][I][J]”

;

; End of file

;

END = “M5”

END = “G0[ZH]”

END = “G0[XH][YH]”

END = “M2”

Below is the last Gcode file that I had the problem with.

Note: Machine was at the zero location as defined by G56 and a new bit was inserted and zeroed via the touch plate, and zero was confirmed in Gsender.

T1

G17

G20

G90

G0Z1.0000

G0X0.0000Y0.0000

S14000M3

G0X-15.6250Y-4.7500Z0.0400

G1Z-0.2953F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

X-8.1788

X7.8553Y-5.5000

X8.2303

X14.8750Y-5.5000

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

Y0.1190

Y4.7500

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

X6.9685

X-8.3788Y5.5000

X-8.7538

X-14.8750

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

Y-0.3541

Y-4.7500

G1Z-0.3415F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

X-8.1788

X7.8553Y-5.5000

X8.2303

X14.8750Y-5.5000

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

Y0.1190

Y4.7500

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

X6.9685

X-8.3788Y5.5000

X-8.7538

X-14.8750

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

Y-0.3541

Y-4.7500

G1Z-0.3878F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

X-8.1788

X7.8553Y-5.5000

X8.2303

X14.8750Y-5.5000

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

Y0.1190

Y4.7500

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

X6.9685

X-8.3788Y5.5000

X-8.7538

X-14.8750

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

Y-0.3541

Y-4.7500

G1Z-0.4341F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

X-8.1788

X7.8553Y-5.5000

X8.2303

X14.8750Y-5.5000

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

Y0.1190

Y4.7500

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

X6.9685

X-8.3788Y5.5000

X-8.7538

X-14.8750

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

Y-0.3541

Y-4.7500

G1Z-0.4804F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

X-8.1788

X7.8553Y-5.5000

X8.2303

X14.8750Y-5.5000

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

Y0.1190

Y4.7500

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

X6.9685

X-8.3788Y5.5000

X-8.7538

X-14.8750

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

Y-0.3541

Y-4.7500

G1Z-0.5266F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

X-8.1788

X7.8553Y-5.5000

X8.2303

X14.8750Y-5.5000

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

Y0.1190

Y4.7500

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

X6.9685

X-8.3788Y5.5000

X-8.7538

X-14.8750

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

Y-0.3541

Y-4.7500

G1Z-0.5729F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

G0Z-0.5710

G1X-8.1788F30.0

G1Z-0.5729F10.0

G1X7.8553Y-5.5000F30.0

G0Z-0.5710

G1X8.2303F30.0

G1Z-0.5729F10.0

G1X14.8750Y-5.5000F30.0

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

G0Z-0.5710

G1Y0.1190F30.0

G1Z-0.5729F10.0

G1Y4.7500F30.0

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

G0Z-0.5710

G1X6.9685F30.0

G1Z-0.5729F10.0

G1X-8.3788Y5.5000F30.0

G0Z-0.5710

G1X-8.7538F30.0

G1Z-0.5729F10.0

G1X-14.8750F30.0

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

G0Z-0.5710

G1Y-0.3541F30.0

G1Z-0.5729F10.0

G1Y-4.7500F30.0

G1Z-0.6192F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

G0Z-0.5710

G1X-8.1788F30.0

G1Z-0.6192F10.0

G1X7.8553Y-5.5000F30.0

G0Z-0.5710

G1X8.2303F30.0

G1Z-0.6192F10.0

G1X14.8750Y-5.5000F30.0

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

G0Z-0.5710

G1Y0.1190F30.0

G1Z-0.6192F10.0

G1Y4.7500F30.0

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

G0Z-0.5710

G1X6.9685F30.0

G1Z-0.6192F10.0

G1X-8.3788Y5.5000F30.0

G0Z-0.5710

G1X-8.7538F30.0

G1Z-0.6192F10.0

G1X-14.8750F30.0

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

G0Z-0.5710

G1Y-0.3541F30.0

G1Z-0.6192F10.0

G1Y-4.7500F30.0

G1Z-0.6655F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

G0Z-0.5710

G1X-8.1788F30.0

G1Z-0.6655F10.0

G1X7.8553Y-5.5000F30.0

G0Z-0.5710

G1X8.2303F30.0

G1Z-0.6655F10.0

G1X14.8750Y-5.5000F30.0

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

G0Z-0.5710

G1Y0.1190F30.0

G1Z-0.6655F10.0

G1Y4.7500F30.0

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

G0Z-0.5710

G1X6.9685F30.0

G1Z-0.6655F10.0

G1X-8.3788Y5.5000F30.0

G0Z-0.5710

G1X-8.7538F30.0

G1Z-0.6655F10.0

G1X-14.8750F30.0

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

G0Z-0.5710

G1Y-0.3541F30.0

G1Z-0.6655F10.0

G1Y-4.7500F30.0

G1Z-0.7117F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

G0Z-0.5710

G1X-8.1788F30.0

G1Z-0.7117F10.0

G1X7.8553Y-5.5000F30.0

G0Z-0.5710

G1X8.2303F30.0

G1Z-0.7117F10.0

G1X14.8750Y-5.5000F30.0

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

G0Z-0.5710

G1Y0.1190F30.0

G1Z-0.7117F10.0

G1Y4.7500F30.0

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

G0Z-0.5710

G1X6.9685F30.0

G1Z-0.7117F10.0

G1X-8.3788Y5.5000F30.0

G0Z-0.5710

G1X-8.7538F30.0

G1Z-0.7117F10.0

G1X-14.8750F30.0

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

G0Z-0.5710

G1Y-0.3541F30.0

G1Z-0.7117F10.0

G1Y-4.7500F30.0

G1Z-0.7580F10.0

G3X-14.8750Y-5.5000I0.7500J-0.0000F30.0

G1X-8.5538Y-5.5000

G0Z-0.5710

G1X-8.1788F30.0

G1Z-0.7580F10.0

G1X7.8553Y-5.5000F30.0

G0Z-0.5710

G1X8.2303F30.0

G1Z-0.7580F10.0

G1X14.8750Y-5.5000F30.0

G3X15.6250Y-4.7500I-0.0000J0.7500

G1Y-0.2560

G0Z-0.5710

G1Y0.1190F30.0

G1Z-0.7580F10.0

G1Y4.7500F30.0

G3X14.8750Y5.5000I-0.7500J-0.0000

G1X7.3435Y5.5000

G0Z-0.5710

G1X6.9685F30.0

G1Z-0.7580F10.0

G1X-8.3788Y5.5000F30.0

G0Z-0.5710

G1X-8.7538F30.0

G1Z-0.7580F10.0

G1X-14.8750F30.0

G3X-15.6250Y4.7500I-0.0000J-0.7500

G1Y0.0209

G0Z-0.5710

G1Y-0.3541F30.0

G1Z-0.7580F10.0

G1Y-4.7500F30.0

G0Z0.0400

G0X0.0000Y0.0000Z1.0000

M5

G0Z1.0000

G0X0.0000Y0.0000

M2