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
G90
M4
; Scan @ 1000 mm/min, 5% power
M9
G0 X105.268Y129.11
; Layer
G91
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
G91
M4
; Scan @ 3000 mm/min, 77% power
M9
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?

Thanks
H.

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.

Unlikely.

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.

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

:smile_cat:

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…