Why is the Z off so much?

gSender ❓ Question
1

I’ve tried to look for other places for the answer before posting and I’m hoping I get some answers. I bought the Longmill mk2 and I’m very new to the CNC world. I make a project in Vcarve and put the tool set for a V-bit 60 percent to go .05 inch to carve up some lettering, however, it punges and I mean plunges to the point that it just nearly broke the router and now the collet is not really seating correctly. I’ve had one of my teachers come in and he’s on a different platform. He made a new file with vcarve with the same thickness and boom again it plunges. I checked to make sure its not the wrong z height. I have the XYZ finding tool. Here is also the G code that I’m just at a loss for. I thought it was due to the probe not being in the tip setting, and that’s not it either.

I’m also flashing new firmware just in case it was something weird because of that…

G38.2 Y15 F150
[PRB:-1.8177,1.5196,-0.1800,0.000:1]
ok
G21 G91 G0 Y-2
ok
G38.2 Y5 F75
[PRB:-1.8177,1.5208,-0.1800,0.000:1]
ok
G4 P0.15
ok
G20 G0 Y-0.4135
ok
G21 G10 L20 P0 X22.5 Y-22.5
ok
G21 G90 G0 X0 Y0
ok
G21 G0 G90 Z1
ok
G90
ok
G20
ok
T1
G17
G20
G90
G0Z3.5625
G0X0.0000Y0.0000
S15000M3
G0X1.7500Y-2.0000Z0.5000
G1Z-0.0500F100.0
G1X8.0000
G0Z0.5000
M5
G0Z3.5625
G0X0.0000Y0.0000
M2
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ALARM:10 (EStop asserted. Clear and reset)
[MSG:Emergency stop - clear, then reset to continue

2

Are you zero-ing your Z off the work piece, or the spoil board?

3

Off the surface of the material. I also have it in Vcarve that way. The program I ran had the material at .75 inches. What i’m seeing is that the z is plunging to .5 inches off the start.

I found out that I’m currently on the latest firmware for the superlong board also so I didn’t flash it. I’m unable to upload because I’m knew but here is the diagnostics:

Diagnostics gSender 1.5.4 Environment OS: Windows NT 10.0; Win64; x64 Homing: Disabled Soft Limits: Disabled Home Location: 11 (Front Left) Report Inches: Enabled Stepper Motors: Unlocked Connection Available Ports: 0: port: COM3 manufacturer: Microsoft inuse: true Connected Port: COM3 Baudrate: 115200 Unrecognized Ports: NULL Machine Profile ID: 6 Company: Sienci Labs Name: LongMill MK2 Type: 30x30 Version: MK2 Limits: X Max: 640 Y Max: 555 Z Max: 200 Spindle/Laser: false Laser Mode Enabled: false GRBL Information Type: grblHAL Firmware Version: SuperLongBoard_B5.0.5b MPos: a: 0.000 b: 0 c: 0 x: -68.6689 y: 50.63236 z: -10.07364 WPos: a: 0.000 b: 0 c: 0 x: 0 y: 0 z: 0 Sender Status: Modal: NULL Tool: NULL Workflow State: idle Homing Flag: false Preferences Jog Presets: Rapid: xyStep: 20 zStep: 10 aStep: 20 xaStep: 20 feedrate: 5000 Normal: xyStep: 5 zStep: 2 aStep: 5 xaStep: 5 feedrate: 3000 Precise: xyStep: 0.5 zStep: 0.1 aStep: 0.5 xaStep: 0.5 feedrate: 1000 Workspace Units: in Laser: Disabled Rotary: Disabled EEPROM Values Setting Value $0 $1 5.0 254 $2 $3 0 4 $4 $5 15 0 $6 $8 1 0 $9 $10 $11 $12 $13 $14 $15 $16 $17 $18 $19 $20 $21 $22 $23 $24 $25 $26 $27 $28 $29 0 511 0.010 0.002 1 14 0 0 0 0 0 0 0 0 11 150.0 4300.0 25 1.500 0.100 0.0 $30 $31 24000.000 7500.000 $32 $33 0 1000.0 $34 $35 0.0 0.0 $36 $37 100.0 0 $39 $40 1 0 $41 1 $42 $43 2 1 $44 $45 4 3 $46 $47 0 0 $56 $57 5.0 100.0 $58 $59-5.0 500.0 $60 $61 1 3 $62 $63 0 3 $64 $65 0 0 $70 $100 11 800.000 $101 $102 800.000 800.000 $103 $110 79.012 4000.000 $111 $112 4000.000 4000.000 $113 $120 8000.000 750.000 $121 $122 750.000 750.000 $123 $130 1000.000 640.000 $131 $132 555.000 200.000 $133 $140 0.000 2800 $141 $142 2800 2800 $143 $150 0 32 $151 $152 32 32 $153 $180 16 150.0 $181 150.0 $182 $183 150.0 150.0 $190 $191 4300.0 4300.0 $192 $193 4300.0 4300.0 $200 $201 22.0 22.0 $202 $203 22.0 22.0 $210 $211 35 35 $212 $213 35 50 $220 $221 22.0 22.0 $222 $223 22.0 22.0 $300 $301 grblHAL 0 $302 $303 192.168.5.1 192.168.5.1 $304 $305 255.255.255.0 23 $307 $308 80 21 $338 $339 7 0 $340 $341 0.0 0 $342 $343 30.0 25.0 $344 $345 200.0 200.0 $346 $370 1 0 $372 $374 0 3 $375 $376 50 1 $384 $392 0 11.0 $393 1.0 $395 $398 0 128 $450 $451 1 2 $452 $453 4 G4P0 $454 $455 G4P0 G4P0 $456 $457 0 2 $458 $459 0 2 $462 $463 8192 8193 $464 $465 8451 18 $466 $467 34 1 $468 $469 50.0 60.0 $470 $471 60.0 100.0 $478 $481 3 0 $484 $486 0 0 $511 $512 7 5 $513 $520 8 0 $521 $522 0 0 $650 $651 1 1 $652 $653 0 2 $654 $655 8 0 $656 $657 1 22 $658 $659 7 3 $660 0 $661 $662 3 0 $663 $664 41759 0 $665 $666 1 0 $668 $730 1 255.000 $731 $733 0.000 1000.0 $734 $735 0.0 0.0 $736 $741 100.0 0.000 $742 $743 0.000 0 Recent Alarms 9/19/2025, 8:56:18 PM EStop asserted. Clear and reset Input: M5 Controller: grblHAL 9/19/2025, 8:23:55 PM EStop asserted. Clear and reset Input: M5 Controller: grblHAL Recent Errors None Terminal History None G-Code File Status No File Loaded Value

4

Can you post your gcode?

5

@Parallaxe What post processor are you using in VCarve? You should be using either grbl mm or grbl inch.

@Kerryh2012 I believe that his gcode is in his first post.

6

Yeah, I can pick the commands out of the console log. I just wanted to see the source before it passes through gsender.

1 Like
7

V-Carve Text_1-V-Carve Text.gcode (12.9 KB)

Profile Line_1-Profile Line.gcode (222 Bytes)

Here are the g-code files that I was using. I can also submit the vcarve file. These were just tests because it had plunged into another folder. Regarding the post processing, I had ran it in inches and mm, I looked back at the post processing and the material was all put in inches but the post processing was in mm. I intend to run this but, I’m unable due to not having access to the software only in the shop I do. I intend to run over there this week give or take.

8

@Parallaxe The first thing that pops out is that the G20 command sets all the movements to inches and the first Z move is to move up 3.5625". You set Z0 on the top of the material. Depending on how high in the clamp you have set your router, by raising that by 3.5625", you may be hitting the top of Z movement. If you are, your Z0 is now gone and all bets are off.

2 Likes
9

Interesting GCode. If GRBL 1.1 then variable usage like Y-3 may not work. Depends on your firmware for the controller.

If you run a simulation on your code what does the simulation do? Watch the values change as expected. There are a couple free to use simulators on line. You should probably watch $ values to see what value is actually getting set.

Sounds like the code writing the work Zero’s aren’t working for Z. I’d check to make sure as well that you aren’t using machine positions instead of work positions for Z.

Loss of true home can cause problems like this as well.

Knowing which type of VCarve and version can help somewhat. . If you run the tool path in VCarve and do single stepping you should be able to isolate the problem or discover no tool path problem, now work other 1/2 of the original problem.

10

@Parallaxe Did you find the solution to your problem?

11

If It’s any comfort, you are not alone. I’m having the same problem with exactly the same setup. Suspended all V-carve tool paths until I get this resolved. Good Luck!

12

I used my own Vectric software and the Z height homing position and starting was throwing it off by a lot and it may also be due to using the wrong post processor. Anyways, been cutting without a problem now once I bought my own Vectric and set it up for myself.