…often leaves the inner parts/circles hanging inside the hole with a tiny uncut part. Its like a 360°cut sometimes does not fully get to a complete 360°. Is there an option or manner in lightburn to set the laser to overshoot 360° hole or a line by a few degrees or mm so the parts would drop out clean ? For bigger parts it a non issue because the parts are easely removed by hand…but when cutting a lot of very small parts i need to push them out using a needle. I read about the tabs…this is not whats causing the problem because i do not use tabs. I want to save some time here.
No crazy materials involved, really thick or unusual composition? If not, Sounds like you may need to do some adjustments. Either mechanical or settings. I’m not sure what you consider very small but I’ve done quite a number 3mm circles and 1.5x4mm rectangles that drop clean under normal circumstances.
If start/stop ends aren’t meeting consistently (99%), that usually indicates something mechanical has some slop in it. Roller cams, belt tension, mounts shaft couplers, pulleys, etc.
There are options for lead-in/out and start/stop dwell, but most people never need to use them.
There is an “overcut” option under advanced tab of cut settings editor window.
Often, that first penetration when you start a cut does not make it thru completely, and the overcut option kind of just finishes off what was started.
Does that sound like your issue ?
Hi . Thanks for the reply. I have the latest version Lightburn installed and tried what you said. The overcut option is under the advanced mode in line. I started with an overcut of 1mm…no succes. I even got it up to 20 mm without any change. If i look at the preview of the thing i am cutting holes in there must be a difference in estimated time between a normal cut (without overcut adjustment) and with overcut( with even 20 mm overcut). The laser time remains equal for both…thats impossible if overcut actually works as it needs to go 20 mm past the normal cut. It does not work at all.
Good point. I should have indicated that I wasn’t assuring anyone that it actually works… only that the option exists and that is what it is used for in every other Cam program.
Maybe I can play with it too in the next few days. I’ll set something up to over run 50mm. That should be visible to the eye for sure. Maybe it really doesn’t work ?
Then a guy should find out where to post a bug.
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As i understand ( by hovering the pc mouse over overcut option) the overcut only works to cut out closed shapes…so just a straight line would not be overcutting. I tried a few different things allready( all closed shapes) …but found there is no difference in time used or distance traveled between parts with or without the overcut active. I am now trying the start pause time and end pause time that can be set in microseconds. Its right above the overcut option. Maybe that could help some as the laser is than set to have a bit longer output at the start and finish…maybe burning trough the small part that otherwise does not cut. For bigger shapes its not a problem the parts have a small point that does not cut fully , as those parts allready drop out by their own weight. But i use this laser often to cut out tiny sewing holes ( from 0.8 to 2mm circles) in leather…if i need to clean out all holes after laser cutting it takes a lot of effort and they are stubborn. Until i solve this problem i use fill instead of line on those tiny holes. That takes the laser a fair bit more time but at least the holes are fully open.
I wonder if putting the stitch holes on a separate layer with a different (slower) speed would help.
Maybe backlash compensation? Not sure if that’s an option. I’ve never looked, but such small moves could easily be borked by a tiny amount of backlash.
Yes…cleaning hundreds of stitch holes with a needle would be both tiresome and time consuming. Almost faster to use a pricking iron. Lol.
You have made some good suggestions…highly appreciated. But if i go any slower on a separate layer i could very well keep using what i am doing now with fill cutting out all the inside material for the small circles instead of using line to only cut the circumference. All and all its just a luxury problem…i used to do that all by hand without to much problems. But i have invested in a 1000 dollar laser and a lightburn licence to speed up the work and accuracy a bit. Works allready great for cutting bigger shapes and engraving intricate patterns in leather…if only i could get it to work for the tiny cutouts.
Thanks allready for thinking/helping to fix a problem…that on itself has become rare these days. 
Out of curiosity, I made a very simple program with two identical, overlaid layers with the exception of one layer having overcut.
It’s two squares of 1mm placed at 0,0. C00 has .2mm of overcut. C01 does NOT. I then previewed and saw no difference, so I saved the gcode and looked at it. The two layers are NOT the same. Notice the extra move of .2mm in the first layer (bold). Circles of 1mm produce a similar difference but the math is more difficult to suss out the exact difference.
I suggest trying it on a real test job.
; LightBurn 1.4.05
; GRBL device profile, absolute coords
; Bounds: X-0 Y-0 to X1 Y1
G00 G17 G40 G21 G54
G90
M4
; Cut @ 2000 mm/min, 45% power
M8
G0 X-0Y-0
; Layer C00
G1 Y1S450F2000
G1 X1
G1 Y-0
G1 X-0
G1 Y0.2
; Cut @ 2000 mm/min, 45% power
M8
G0 X-0Y-0
; Layer C01
G1 Y1
G1 X1
G1 Y-0
G1 X-0
M9
G1 S0
M5
G90
; return to user-defined finish pos
G0 X400 Y400
M2
Just a thought do you have enabled tabs and brisges?
Hi . No i did not use tabs or bridges…it was one of the things i chequed after having the problem. If it were tabs and bridges all parts being cut would have those. Thanks for the reply and help
Had the same issue, fixed by lowering the power and changing to two passes, when cutting, the power stays on thru the two passes and the part drops out. additional time for 2nd pass is minimal.
Good suggestion , thanks !
Do you have max and min power settings the same. If not, beam power may be dropping to the min power setting as the beam approaches the end of the cut.
Hi , thanks for reply. Not sure were that max and min power setting is…could not find that. Maybe a printsreen to locate where i can set those?? I have constant power mode enabled in the layer popup when cutting in line mode.
For a diode machine, Min/max is only available on grayscale image mode. I believe it’s a standard setting in all modes on a CO2.
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