Hello,
Trying to apply a kerf to a shape with holes in it. The kerf applies fine to the holes but not the outline (see picture-I’ve exaggerated the kerf for illustration).
Select open shapes shows the outline as open, yet it is not. I’ve broken it apart and reapplied auto join and it is selectable as a single continuous line.
What could be causing this? I’ve tried recreating my steps a zillion times, but no luck.
Thanks for any help!
Corina
kerf test.lbrn2 (11.3 KB)
The large shape is not closed
If LightBurn indicates that the shape is not closed it will treat it as so in any case.
Looking at your outline it looks like there’s a problem at closing the start/end segments. There was overlap of the segments rather than the end nodes joining.
I’ve separated them out here to illustrate:
thank you for your reply,
I’m zooming in and looking at the nodes, but not finding overlaps. How did you isolate the problem?
Also, why can I select the whole line if it’s not joined (as I did with auto join)? Is there a way to fix this problem that I can’t see when selecting it?
Thanks again,
Corina
You will have to move the nodes to see the overlap. They’re literally on top of each other. I’ve moved them in my screenshot.
Disconnects will by definition occur at the start and end of a shape. When editing nodes you can see the green squares representing the start/end nodes. For a closed shape you will only have a single green square node. When moving that node both side segments of that node should move along with it. If the node separates from adjacent parts of the shape then the node is not joined.
Imagine a loop where the ends are not joined. You can select the whole line but still not resulting in a closed shape.
Thank you,
But is there a way to know without trying to move nodes? A way to see where in my shape the problem is?
Actually, a better question would be: can I close these overlapping nodes? Without having to go through all the shapes in a design and finding possible overlaps?
Thank you again
Well, it tell you the shape was open is the first indication. Then you go looking for where that might be. The method I conveyed earlier is a way to do that.
In this case I reviewed the model again and you can visually see the separation at the ends.
I guess this depends on what you could possibly expect it to do. I don’t see a practical way of automating this without a fundamental change to your design.
You could attempt to use “Close shape with tolerance” to do this but this wouldn’t be acceptable solution for me given the type of change. This will be up to you in terms of your work tolerances. In this case if you close with tolerance you’ll have areas burned more than once and slightly off from one another. Additionally if your plan is to incorporate kerf that would need to be accounted for. That might actually “even out” the issue caused by this but sounds to me like if you’re at a point where you care about kerf for a better fit that you’d want ultimate control over how the shape is closed.
I guess the real question is how did the design end up in this state? Any proper design would not have left this in this state to begin with.
good question! I’m trying to figure that out myself. I exported it as dxf from Fusion 360 and in Fusion it is most definitely a closed shape as I drew it line by line so I know all the ends connect.
That’s funny that your method brings you comfort in this case but for me this gives me the opposite feeling. I suspect your model is not fully constrained or the joints are not joined at this location.
I’m sorry but your answers seem very condescending. I’m doing my best to learn this software. As for Fusion, my sketch IS constrained and there are no gaps or overlaps. Why the dxf shows up that way I’m unsure.
I came to the forum for help. I asked honest questions hoping a newbie (to Lightburn) would be helped without being made to feel foolish.
Sorry. Not meant to be condescending. I meant I found it amusing that we had different takes for the same approach. In my learned experience I have been conditioned to think of repeated manual executions of things as something not to be trusted no matter the amount of care put into it. It’s a pessimistic model that assumes that if the system allows for error, error is inevitable.
This is in contrast to the feeling of assurance that you seemed to have that since “you did it yourself” that it was more likely to be okay.
Definitely did not intend it to be condescending so apologize. It was more of a “huh… that’s interesting.”
In any case, I would still tend to think that something in the original design is likely not joined. Or it’s a bug in LightBurn import but this isn’t the type of bug I would expect since the placement of the nodes are not aligned. Normally LightBurn bugs with regard to import are about how some nodes that are joined that should not be, but node location is usually correct.
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