Creating unclosed vectors for rotary engraving

Hi,

I have a repeating vector pattern I want to engrave onto a wooden dowel (45mm dia). I’ve got the rotary adaptor setup to apply the pattern over 360 degrees but I have a minor problem when setting the graphic to fit within the flat drawing so that the pattern appears seamless.

I achieved this by creating a rectangle for the area to be engraved and then scaled the pattern so that the 0 degree and 360 degree edges line up. I then used booleans to remove the unwanted part of the pattern. The problem I have is that the boolean operations create closed vectors at the edges where open vectors are required (for the seamless effect),

I can ungroup the pattern and then edit the edge vectors create matching open vectors on each side. Probably best to see the the attached images for a clear idea of what I’m trying to achieve.

What’s the best way to achieve this outcome? Maybe there is another solution… I did think of drawing a spline around the closed vectors but this won’t be a simple solution.

Early days with LightBurn for me. Looking really good now I have changed the M2 controller for a mini-gerbil.


I think LB only does that when the layer is set to fill, if it’s set to cut it doesn’t add these lines I believe.
Have you tried using the node editor and deleting the unwanted lines?

Correct. Cut Shapes Tool - LightBurn Software Documentation

Key points to remember:

  • The last shape you select is used as the cutting tool
  • The shape used as the cutter must be a single closed shape
  • The cutting tool shape is discarded - if you need it again, make a duplicate of it (Ctrl+D)
  • Shapes that are cut will be closed if they are set to ‘Fill’, or left open if they are set to 'Line’
1 Like

Thanks for the quick response.

I assumed the shape setting of ‘Fill’ and ‘Line’ are the Cuts/Layers mode settings. Both my objects (pattern-black and cutting tool - red) are marked as Lines. I checked using the boolean intersection tool and get closed vectors at the edges.

Have I misinterpreted something?
LightBurn 1.0.01 on macOS Big Sur 11.4. lbrn2 file attached.


koru pattern test 170x163mm.lbrn2 (1.6 MB)

That seems a bit odd to me but I’m very new to this. I expect someone else with more knowledge will be able to help out.

What additional help are you requesting, beyond providing confirmation of your understanding, provide a link to the documentation for the ‘Cut Shapes’ tool, and bold the exact quote from that documentation?

@Rick

Thanks for the response.

Your image shows what I understood to be your meaning (Cuts/Layers settings)

The issue I had is that when the Cuts/Layers mode is set to Line the result I got with boolean operations was a closed vector. You may say “Of course”!

Your answer led me to search for the ‘Cut shapes tool’ in the docs which I had not come across before. Watching the referenced videos showed me how I should be cutting open shapes. Simple indeed.

For anyone reading this at a later date here is the documentation reference.
Cut shapes docs

Got there in the end - thanks for pointing me towards the answer.

2 Likes

Apologies, I thought you were already using the ‘Cut Shapes’ tool. Obviously I didn’t read your post properly!

Thanks @Marcus . I think I had missed the ‘Cut shapes tool’ link as it is greyed out unless a valid set of vectors have been selected (in the correct order). I’m new to LightBurn so I’m still getting used to the way it has been designed.
I’m really liking it especially after k40-whisperer/Inkscape workflow.
I also use Fusion360, Shapr3D and Affinity Designer for CNC, CO2 laser, and 3D print designs. Thanks for your help

You’re welcome! I’m new to LightBurn too as well as lasering in general (I’ve been using LB & my Ortur for a whole two weeks now!). I have had some experience with a Rofin (now Coherent) fibre laser almost 10 years ago.

I use Fusion360 too as well as SolidWorks (in my day job), Affinity Suite, Corel … the list goes on! I do a bit of 3D printing too with a Formlabs Form 2 SLA printer which is quite handy :wink: