Covert NURBS to arc and lines (no polylines)

Hi

Do you know a software that convert nurbs in arc and lines?

thanks

Hi, i can :) please share an e-mail

I am into software, math aproximations, etc / kindly :)

Hi KadKam - Most nurbs modellers have a feature where you can capture the isocurves of the surface as lines. Or you export the nurbs as a 3D dxf and it will capture the isocurves. So choose the density of the isocurves that you need then find the feature that captures them or export them as dxf.. The lines will not be arcs unless the surface is a ruled surface (or spherical) by the way. Peter

you can also create a mesh on that surface and extract the mesh lines. You can make tri meshes or quad meshes in Rhino3d for instance.... then extract the mesh as separate lines. Again the "lines" will not be arcs but contiguous lines.

It used to be quite common for CAM systems to convert splines to arcs and lines.I used to share an office with a guy who used Alphacam and this was the way it dealt with splines,I'm sure there are others and I seem to remember that Rhinocam had the option of doing the same thing.

My Rhinocam 4 (don't know new versions) have a command "Convert Curve to Arc" but if I load complex figures like vectorized bitmap logos, the result to be converted are combinations of lines, polylines and nurbs and Rhino fails, it creates me for the majority, many microsegments and some arcs.
I need a program that basically traces this complex vector logo from scratch and, as I was saying, converts it into pure lines and arcs.
This type of simple logos are necessary for CNC or laser processing, where it is often necessary to offset the logo due to the thickness of the tools or the laser.

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I need a program that basically traces this complex vector logo from scratch and, as I was saying, converts it into pure lines and arcs.

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hy kadkam :) i can deliver a custom application, to do what you need

if you wish, please share some such images, and whatever demands you wish

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often necessary to offset the logo due to the thickness of the tools or the laser

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auto-offseting ... ok; what else ?

end result can be as simple as a single mouse click, all proces going on it's own, generating cnc files and cad files / kindly :)

Linuxcnc has native support for NURBS
https://linuxcnc.org/docs/html/gcode...code:g5.2-g5.3
But whether you can find a CAM package that can use it is another story...

Hi,
in Fusion you can draw using splines and then run it through CAM to get Gcode. Not sure how the conversion is done or when, but a spline drawn in a part is faithfully machined.

Craig

Hello Kadkam - Converting an arbitrary NURBS curve to "lines" and "arcs" is a bit tricky : 1) there will be no actual arcs in the nurb 2) a nurb is rubbery polynomial entity that depends on its native tolerance settings for what it "actually" is. Rhino will do what you want but I suggest you forget about the arcs and just convert it to a contiguous set of straight lines that fit within the required tolerance. The arc requirement will get you into trouble... My experience with basic users of Rhino is that they do not understand how to set it up to a manufacturing tolerance level. Its default tolerance is more useful for low level animation work not engineering work. So look up its help for tolerances and reset it to a suitable tolerance for what you want to do. If Rhino is set at default tolerance then when you bring something into it defaults to the low tolerance and after that you cannot improve its tolerance or accuracy.

A CAM system will create a bunch of straight line anyway. Even if it seems to work with arcs and nurbs these get broken down to straight lines eventually. You need to read up on how the geometry interpreter does this for each system as they can be a bit different system to system. Peter