iKier K1 Pro 24W – Red crosshair turns off during Frame, but stays on with M2

LightBurn Software Questions
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1

Hello LightBurn Support,

I am experiencing an issue with the red crosshair positioning light on my iKier K1 Pro 24W laser when using the Frame function in LightBurn.

Machine and software:

  • Laser: iKier K1 Pro 24W

  • LightBurn: Core 2.2.00

  • Also tested with LightBurn 1.7

  • Controller: GRBL 1.1h, iKier firmware

  • Firmware identification: [VER:1.1h.20230501:]

  • Laser mode: $32=1

  • S-value max: $30=1000

Problem:

When I press Frame, the red crosshair positioning light turns off during the framing movement and comes back on when the movement finishes.

This happens with both rectangular framing and outline framing.

However, when I move the laser using the Move panel arrow buttons, the red crosshair stays on throughout the movement.

The Laser On When Framing option is disabled. I do not want to enable the main cutting laser during framing.

Tests performed:

  1. Framing with my original GRBL device profile: the red crosshair turns off.

  2. Framing with a newly created GRBL device profile: same problem.

  3. Framing in LightBurn 1.7: the crosshair turns off immediately in both framing modes.

  4. Moving the laser using the Move panel: the crosshair stays on.

  5. Running the following G-code file through Run GCode:

G21
G91
G1 X100 Y0 F6000 S0
M2

Result: The red crosshair stays on throughout the movement.

  1. Running the same file without M2:
G21
G91
G1 X100 Y0 F6000 S0

Result: The red crosshair turns off during the movement.

This result is repeatable and suggests that the presence of M2 in the streamed program affects the crosshair behavior.

G-code sent by Frame in LightBurn 2.2.00:

G00 G17 G40 G21 G54
G91
G1 X75Y0S0F6000
G1 Y-65
G1 X-75
G1 Y65
G0
G90

There is no M2 at the end.

G-code sent by rectangular Frame in LightBurn 1.7:

G00 G17 G40 G21 G54
G91
G0 X0Y-91
G1 X100S0F6000
G1 Y91
G1 X-100
G1 Y-91
G0 Y91
G90

Again, there is no M2.

My questions:

  1. Is this a known compatibility issue between LightBurn framing and iKier’s customized GRBL firmware?

  2. Is there a way to make the standard Frame button send an M2 at the end of the framing program?

  3. Is there another supported way to keep the red crosshair illuminated throughout framing without activating the main cutting laser?

  4. Could this behavior be addressed in a future LightBurn update?

I would strongly prefer to keep using the normal Frame button rather than running a separate G-code file for every job.

Thank you for your help!

2

This is really strange. Gcode is executed in order, so the M2 command AFTER the others should not affect the laser function at all.
The only explanation I can think of is that the firmware reads ahead the commands and changes execution…

3

Thank you for your reply.

I agree that M2 should not affect a movement that precedes it. That is exactly why the test result surprised me.

I repeated the test using LightBurn’s “Run GCode” function:

  • G21 / G91 / G1 X100 Y0 F6000 S0 / M2 — the red crosshair stays on throughout the movement.

  • The same commands without M2 — the red crosshair turns off during the movement.

The behavior is repeatable.

Could the difference be related to how LightBurn streams the G-code or how the iKier firmware handles its command buffer?

Is there any additional diagnostic test you would recommend to distinguish a firmware issue from a G-code streaming issue?

My goal is still to make the normal Frame button work without activating the main laser.

Thank you!