Contour Curve problem!

Which commands do you have applied?
Is possible to apply them automatically (by plugin)?

This video shows one sequence, if you only need sections you can reduce the procedure somewhat:

Briefly:

Remove top and bottom surfaces if it’s a solid
ChangeDegree to 1 in U and V
DivideAlongCreases (creates a polysurface - could be invalid though)
Contour
SimplifyCrv (on the created contour curves)

Should produce clean polyline contours. Note that this will only work correctly on polysurfaces that have linear edges. I will look into automation, but of course it’s better to just have correct objects to begin with and not have to fix them afterwards.

–Mitch

Since the object is an extrusion with vertical walls all the contours will be the same curve.

DupEdge for all the bottom (or top) edges

Array

Results here Lettera S o 5 DC.3dm (1.4 MB)

Yes, except those will be the same crappy degree 3 curves with stacked control points at kinks… --Mitch

Turn on Osnap for endpoint
Polyline: trace from corner to corner
Surface → Extrude curve

Done.

FWIW, here is a hack to attempt to fix your objects automatically. No guarantees, it’s actually pretty hard to fix this stuff and a lot of places it could go wrong.

First, turn off CheckNewObjects, otherwise you are likely to get a bunch of bad object messages that you will have to click OK for each one. Then just select the objects to fix - limit the selection to only the ones that need fixing - and run the script. Check the results carefully. Hopefully will change all of the planar-sided stacked control point degree 3 surfaces into simple planar polysurfaces that should section/contour nicely. If the object was solid, it should stay that way, if it’s open the script should still work.

–Mitch

FixStackedPtSrfs.py (2.7 KB)

I may not understand this but as I make these kind of shapes all the time, and in my forum teach people how to do stuff with this. The shape I downloaded looked like it came from an .Obj file. I selected create “Wireframe”, from the “Curves” menu. Now you have something you can work with. I removed the faulty curves and replaced them using “Osnap”, with a single “Curve” with no extra “Control Points” where necessary (about 3 places I believe. From that point, I under “Surfaces”, I extruded the lines to make the walls. I then :"Joined them, using under “Solids”, I used "Capped Planer Holes’, done. about five minutes worth of work. I do not know why you are spacing these so tight. It would be easy, using the Array command, to slice this into Rhino’s limit, then “Cap Planar Holes” again. If you are making paper sheets, and the are as thick or acrylic, etc, the, using a router, or other CNC machine, you would only need the Cap on top for the machine to follow, of course, this makes no sense as the corners are sharp, and end mills and routers are not that small. I own a machine shop and could easily fabricate this part with the file I have uploaded. I did not bother checking dimensions, I just used what you posted. If the letter is more than 5 feet tall, I would outsource it. :slight_smile:

Lettera S o 5-wrmdzathros.3dm (189.2 KB)

We are CNC /laser machine builder. We use the laser source for slicing 3D models for create mould or punch, starting from 3D drawings.
The drawings are supplied by customer and with automatic process we send all the informations to the machine under SVG files way.[The conversion is made with our plugin]. All the process must be automatic, not manual intervention is needed, but with this 3D model is not possible,the customer must fix something.

Well, I spent 10 years programming 4 axis CNC machines for Sikorsky Aircraft, and with the file I uploaded, the file only need be exported in the .svg format, and if he can use it, I have done CNC programming/fixture design most of my life, I worked for Perkin Elmer, and parts I made are inside the Hubble Space telescope. With laser cutting, all that needs to be followed is the profile anyways. On the other hand, if you have all the dimensions of this part, and seeing how simple of a shape it is, why could you not fix the drawing, as I did and charge him for that too? Just my 2 cents worth. I have programmed enough CNC machines for a lifetime. I have received enough blueprints that looked like Escher drew then, and had to fix them, so they fit this time and space cone we are in. :wink: