Is it possible to repair a fragmented Bezier curve?

Hi! I use SU to create files for laser cutting, exporting them to pdf and sending them to my laser cutter.

I have a problem with a file in that most of the Bezier curves are fragmented into segments and the laser cutter does not cut them continuously. It cuts one segment, jumps to another curve and cuts one segment, then back and forth and back and forth. Some of the curves cut smoothly and are beautifully continuous. What is even stranger is that these curves are all copies of one another, yet I get different behaviors. The fragmented curves mean the cutting time is a lot longer and the curves get little burnt spots at the stopping and starting points.

Reading in the forum I see that there’s ways Bezier curves can be fragmented. I could redo the file and be very careful, but I wonder if there is a way to repair these curves?

Thanks for any ideas!

You are running into the inherent limitations of SketchUp. SU has no true Bezier curve entities so what the Bezier add-ons produce is a series of straight line segments. Also, when you export to a 2D type file like PDF, the same happens to arcs and circles too.

If your laser cutter supports the DWG or DXF format, a solution to reduce the number of endpoints in your curves would be to construct them as a series of tangential arcs, and then to export to DWG or DXF as a 3D Model file. That would preserve the arcs, and it would also likely preserve your welded curves, even if the segmentation would remain.

It would also be possible to postprocess the files in a CAD application. For instance, in AutoCad, you could first join the curve segments into a polyline, and then convert the polyline into a spline curve using the Fit Curve method. It is a lot of work, though.

You might find Curvizard helpful, it will weld, simplify and smooth curves that have become segmented, it won’t return them to editable Beziers though.

Thank you! I’ll need to avoid using these for laser cut files…

Thank you! I tried Curvizard, and a couple other welding plug-ins. They welded the curves, but nothing changed when I sent the files to the cutter. I’ve redrawn the curves with the arc tool, and it’s better now.

Might want to try out Fabber extension.


The side effect from turning all segments edges again into a single SketchUp polyline is that all edges oriented the same way ((p1→p2), (p3→p2) becomes (p1→p2), (p2→p3)). A clever laser cutting software would minimize the travel distance to the start of the next line and prefer following an edge that starts from the end point of the previous edge.