I feel this is a Lightburn settings problem. I’m cutting 3mm plywood with an e40 laser module and there are some curves the laser seems to not completely cut. It only seems to happen on curves near the end of the shape.
The laser is clean, the board it flat, it can easily cut through the material at the speed. 300mm/s.
I found a post that suggested changing the x and y acceleration and it seems to resolve the issue for some curves but not all of them.
Any suggestions?
In the early 8-bit grbl, the controller uses a max speed for each axis. In a sharp corner, if the laser has to slow down, power will decrease to match the loss of speed in an attempt to balance it out.
I’d like to see the Machine settings to see what the ‘Max Rate’ for the X-Axis and Y-Axis are.
Since you’re tinkering (and optimizing) you probably already know about $$ in the Console window. 
Thx for the reply!
I’ve uploaded my machine settings. I did try adjusting the max rate lower, did not make a difference. I adjusted the angles and rotation of the curve I’m trying to cut as well just to be sure. It’s always the end of the cut. I also tried constant power mode, set the minimum spindle to 250, and set the maximum spindle to 255. Still no luck.
Any idea from the machine settings?
I believe so.
Your X Max rate and Y Max rate are 15,000 mm/minute.
You are attempting to cut at 300mm/second which is 300mm/s * 60 s/min = 18,000 mm/min.
I would recommend setting the Max rate defaults back to 15,000 mm/min and reducing your commanded speed. 12,000 mm/min might still be fast but it should get you out of the ‘cornering algorithm’. You may notice that this setting doesn’t increase the engraving time very much because the controller wouldn’t have allowed the engrave head to outrun the max rates.
This should address the missing part of the engraving. Please also reset the minimum spindle setting back to the factory numbers.
When the overspeed is commanded, the Laser power output is reduced to make up for the speed that can’t be reached. This is caused by the cornering algorithm in GRBL so the effect is further exaggerated in corners and when slowing to a stop.
The code is well commented but pretty heavy right here.
Here’s a summary written by Sonny (Sunjeun) - the same author that wrote the code.
Still pretty heavy.
Lowered the max rate and seems to be a lot better! Thanks!
You lowered the max rate on the control board in GRBL (in the console window) or your cutting speed in the Cuts/layers window in LightBurn or the Jog speed in the Move window in LightBurn?
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