Z movement issue

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

Welcome @Olde_Yankee
could be multiple issues, you should open a new topic. This one was solved.

@Olde_Yankee I’ve moved your post to a new topic, Wally. As @Shipwreck pointed out, that previous issue was resolved. I should have closed the topic. I have now.

I’ve also been experiencing issues with my laptop (ASUS ViVoBook, Windoze 11, Intel 7 chip w/Nvidia GeForce RTX). Specifically, initiating a Homing sequence with the limit sensors not activating and the Z axis crashing in the upright position. This has happened upon first starting up the machine. Solved by powering up the long board and VFD before connecting the USB to Longboard. This will occur occasionally when re-Homing the machine and solved by shutting down the Longboard, disconnecting the USB cable, and closing and restarting Gsender. Then reinitializing everything. The first time this happened none of the limit switches would activate until doing the aforementioned procedure. The LongMill was received in early January of 2024.

gSender has nothing to do with the homing sequence past sending the $H command to the firmware - the homing cycle is entirely handled by the firmware. I’d double check your wiring if you’re intermittently having limit switches fail during homing.

@Olde_Yankee
with what your describing and I’m guessing you have a spindle. Do you have the correct power requirements for the circuit. You are pushing the max of a standard circuit with just those, do you have more things plugged in? Weird things and shielding issues can happen from too much draw.

It is a 20 amp circuit with laptop, Longboard, and VFD plugged into a surge protector. Circuit has a ground fault breaker. I have used setup with a Makita router before, with a Rigid vacuum for dust protection included on a 15 amp circuit. 15 amp circuit is with a standard breaker, but it was a series of 25 ft extension cords. Changed over Makita to a 1.5KW PWCNC 65mm spindle and switched dust collection to my Jet 2hp dust collector on another circuit altogether.
I didn’t think it is an issue directly connected to Gsender, but it appears to be an issue with the communication causing the Longboard to behave inconsistently. As none of the equipment is medical or military grade my only diagnosis is computers need to be cold booted regularly to clear the caches to prevent aberrant behavior. I’m debating on switching out the ground fault breaker also as I’ve heard some electronic equipment have issues with them.
I’ve made checks of all the connections to the Longboard and the connectors are fully seated. Additionally, as soon as the machine is cold booted with the USB disconnected and Gsender rebooted the limit switches work.

Are you re-establishing G56 as your work coordinate offsets when starting the next toolpath?