Bug? Overlapping continuous internal cut line missing

Hey y’all,

I got a weird bug, namely, I’m missing an internal piece of a continuous cutline.

The shape is essentially like a closed loop, twisted over itself, so it could cut the thing in one continuous path, rather than two pieces.

Thoughts?

Let me know if you require further information.

Thanks :slight_smile:


Lightburn_overlapping_line_missing_moors7.lbrn2 (6.8 KB)

I have no idea why it acts this way, but I can tell you how to work around it. Go to Node Editor. At the intersection of the 2 areas hover over the nod that is there, click the D key to delete the node. You will need to do this 3 times until there is no longer a node there, just crossing lines. Then Arrange Menu>Break Apart. It will cut as you desire.

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Deleting the nodes made no difference, unfortunately:

Figured I’d break the shape in the corner, and have it start there (as confirmed by the starting point arrow). That, too, it ignored:

If I leave a small gap, it does work???

It’s… weird…

Did you use the break apart command on the entire shape before testing? Just removing the nodes did not do it. I had to break apart as well.

That’s the problem: although it’s not made clear in the doc, a closed vector path must have a distinct “inside”, which means the path cannot cross itself.

Also, that corner has three coincident points, one marking the start / end of the whole path.

AFAICT, the path planner follows very simple rules, so trying to outsmart it generally leads to heartache & confusion.

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Fair enough for the closed shape, but what about the one where I broke apart the corner?
Then it would just be a string that just so happened to have the same start/ & end point :thinking:? Does it treat the open loop like a closed loop if those point coincide?
The small gap does make it behave as expected.

@thelmuth, I broke apart the corner with the node edit tool (B), which I figured to be enough, as breaking all the nodes felt a little unnecessary?

Sure does seem to be true, and weird stuff happens if you do anyway:

Although I find that behaviour unintuitive. For filling, it makes a lot of sense, but as a cut/score line it doesn’t? I just want the laser to follow the lines as though I’m “drawing without lifting the pen from the paper” kinda thing. I feel like that’s not an unreasonable usecase?

Leaving a stupid small gap does, once again, work to make it behave like expected:

This is a new strange one.
If I set the layer to Fill the shape is there :smile:

You have a Kerf in your Layer settings. Remove the Kerf.

Well, I’ll be da…

With the kerf disabled, it does work as expected. That most likely is caused by the inside-outside nature of the kerf.

Thanks :slight_smile:!

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I found a solution to your problem. It is connected with the correction of the cut on the laser width. Set it to 0 and everything will work. But the part will be smaller by the beam diameter if you have a laser or the cutter diameter if you have a milling machine.


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