Cut settings, "Fill shapes at once" not working properly(?)

Hi!

I’ve been testing Lighburn for few weeks and I encountered a weird problem when using “Fill shapes at once” in Cut settings.

I added the same SVG file in two cut layers, Layer 00 has “Fill all shap at once” checked and Layer 01 has “Fill shapes individually” checked.

image

as you can see in the image, layer 00 is missing parts of the text and has stripes where cut layer 01 is ok.

Is there some setting I’m missing that causes this kind of behavior?

I’m using Stepcraft with OptLasers laser and I’m exporting GCode to UCCNC controller.


I investigated the generated .gc file and there are parts where laser is tuned off for longer periods of time when it should be on.

Here is another picture where I had PNG and SVG files in the same burn:

It does the same with PNG and SVG when fill shapes at once is selected.

Any idea what is wrong in my cut settings?

Br,
Jukka

This may be a speed different: the machine cannot go as fast while filling individual letters as it does while scanning an entire line at a time.

You can feed the machine’s acceleration (GRBL $120 and $121, your machine may be different) and the layer speed into the RepRap calculator to find the distance required to reach that speed:

If the machine has relatively low acceleration, it may require (much) more than the 2.5% overscan distance to reach the commanded speed, which would account for the relatively darker sides of the “All shapes at once” text.

Hi!

Thanks for the tip, I’ll try that setting soon.

I also slowed down the machine feedrate (from the UCCNC controller) down to 10% of the Lightburn set feedrate, but it did the same.

Even when ran in the 10% feedrate, the Lightburn GCODE commanded the laser to turn off during those “unburnt” areas as seen in the image.

Br,
Jukka

Upload the *lbrn2 and the corresponding G-Code files so we can all see what’s going on.

Hi!

Here are the files:

metalworks -test.lbrn2 (82.8 KB)

metalworks - test.gc (269.9 KB)

Br,
Jukka

You have very little overscanning enabled, and you’ve told the machine to go 2000 mm/minute. Is your machine capable of that speed? That would be almost 79 inches per minute. According to an online doc I found, the maximum speed of the V1 machine is 30 mm/sec, or 1800 mm/sec.

Does the machine appear to be varying in speed, or is it consistent? Is it actually getting to the requested speed? If you run the engraving slower (say 1000mm/min) does it change the outcome?

Hi!

As you can see in the image in my first post, in the lowest image with different font is done also at 2000 mm/min speed with no issues. Speed seems to be constant and if I set the speed eg. 250 mm/min the result is the same.

If I use UCCNC’s own laser-engraving-plugin with 2000 mm/min it does the image just fine at that speed (but the plugin is very limited and crappy, that’s why I’m testing and moving to Lightburn)

Here is a link to a short video of realtime GCODE of single “METALWORKS” PNG engraving: https://photos.google.com/share/AF1QipNRDGTADgss_8RzdWLRxxSqO50LxfuMaC-AB3ttMsccoQrEfmvM6rUPK8yi0ZyuTw?key=VzJUS0tpeTFURnB1bHkzQlNNTE9Lbkc1OFZXaGFR

As you can see from the GCODE box, laser is commanded to turn off with “M10 Q0” command and then X-axis travels long way without toggling the laser. It should toggle the laser to burn letters “ALWORK”.

Is there any reason why the different font works just fine?

Because the two lower samples are both PNG images with the same settings, it looks very much like the laser head is unable to switch as rapidly as is required to form those shapes.

The split letter bars are about 0.5 mm wide and the laser is travelling at 33 mm/s, so the laser must switch on and off within 15 ms. That should be no problem, but the evidence suggests it cannot do that.

That also explains the different between the two upper samples: the top one is scanned from side to side (so the laser can reach top speed), while the lower one is scanned one letter at a time (so the laser cannot reach top speed).

The dropouts become worse in the middle of the full-width scans, which suggests that the speed is not constant, for the reasons mentioned above.

This is a hardware problem, not a software problem.

One possibility is that the power supply is inadequate, so that the voltage is sagging low enough to disable the laser. The supply must be provide more than about 4 A for the laser alone, so if it’s shared with the rest of the machine it’s likely to be inadequate.

  • What is the power supply amp rating?
  • Is it dedicated to the laser head?

I’m using PLH3D-15W Laser Head for Laser Engraving & Cutting - Opt Lasers with OptLasers dedicated power supply.

But I’m wondering why the PNG image is engraved successfully with UCCNC own engraving plugin at the same speed (2000 mm/min) as Lightburn?

If you check the video I posted, there you can see that the GCODE sets the laser off, when it should be toggling, at 7 seconds to 13 second time.

I’ll run a test where I set the speed to eg. 200 mm/min, so then there should be plenty of time to turn laser on and off.

Br,
Jukka

We would need to see the GCode generated for both to compare them to understand why one works and one does not.

That I would like to see myself too. Unfortunately I’m not able to extract the GCODE from the program :frowning:

I did yet another test with recuded feedspeeds:

And it seems like no matter what the feed rate is, the results are the same when using “Fill shapes at once”.

But thanks for the support so far. I’ll run more tests with different font sizes to find out what might be the issue.

Br,
Jukka

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