G0 accellerates too fast

Hi, I am using Lightburn 1.2 and did a number of material tests, to compare the Sainsmart 3018 ProVER (GRBL 1.1f) with the Sculpfun S9 (GRBL 1.1H). The idea behind my test is to see if there is a factor in power/speed to use the same LB design on both machines.

On the 3018ProVer, I have $110 and $111 (Max Speed) on 3000 mm/m and I have currently the $120 and $121 on 275 mm/m2 (accelleration). When I move the laserhead with the arrows at a speed of 3000mm/sec, it all works fine. When I start the material test (which uses the G00) the system crashes as it goes too fast too soon.
If I download the G code and replaces the G0 by G1 (and add a F3000) all is well again.

This is the G Code of the test
; LightBurn 1.1.04 (This is on my desktop, the previous version of Lightburn)
; GRBL device profile, absolute coords
; Bounds: X94.4 Y116.32 to X172.1 Y201.68
G00 G17 G40 G21 G54
; Scan @ 1000 mm/min, 5% power
G0 X105.268Y129.11
; Layer
G1 X0.833F1000S0
G1 X5S50
G1 X0.833S0
G1 Y0.2S0
G1 X-0.833S0
G1 X-5S50
G1 X-0.833S0
G1 Y0.2S0
G1 X0.833S0

; LightBurn 1.2.00
; GRBL device profile, current position
; Bounds: X0 Y0 to X78.55 Y86.23
F2000 G1 G17 G40 G21 G54
; Scan @ 3000 mm/min, 77% power
G1 X68.549Y71.977
; Layer
G1 X2.5F3000S0
G1 X5S770
G1 X2.5S0
G1 Y0.2S0
G1 X-2.5S0

So Q1: can it be true that G0 is not taking the acceleration in account?
Q2: if so, can I disable G0 for this machine?


How did you arrive at these values? These look larger than any values I’ve ever seen for 3018 machines. I suspect you’re never actually reaching these values.


I’d suggest dramatically reducing those values to see how it behaves. Acceleration around 10mm/s^2 and speeds around 500 mm/m.

Then you can increase values incrementally to test limits.

I don’t believe LB has any setting to disable use of G0. LaserGRBL does have something like this to avoid rapid moves.

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Don’t know if this applies, but this video is pretty good on how to tune up a machine like yours.

I ended up 'de’tuning mine. I was afraid it would shake itself to death. It’s a good basis…

Good luck


From my experience, the most common values for an S9 laser are up to 5000mm/min as speed and 500mm/s² as acceleration. I usually set this even to 250. I have all recommended firmware settings listed here: Firmware Update & Settings - Diode Laser Wiki

Thank you. I have brought everything down again. I m still puzzled when I use the same speed in the settings and when moving, the G0 doesn’t work while the G1 works… Probably beyond me. But thank you for the link!

Hi @misken, thank you. very interesting site. I’d wish there was something as extensive as that for the 3018… But I have learned again…

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