Cutting plotter issues / Probleme plotter de découpe

*** for (bad  english, see below !! ****


Bonjour !

Débutante sur LibreCAD, je m'en sers pour créer des patrons pour le cuir, destiné à un plotter de découpe numérique.
Ce dernier trace puis coupe chaque pièce dans le cuir.

Je crée des dxf en 2D relativement simples, avec un seul calque.

-1er problème :  certaines découpes ont des parties à évider : le plotter les ignore tout simplement (pas de traçage ni de découpe)

-2e problème : certains arcs de cercle/ cercles ne sont pas pris en compte, mais sur deux fichiers seulement : un qui représente un cercle de 85 mm de diamètre qui n'est même pas détecté par le plotter. Et un autre dans lequel il y a un arc de cercle de rayon 43,33 mm : là l'arc est tracé, mais en décalé par rapport au reste de la pièce (ce qui n'est pas le cas dans le dessin), et il n'est pas coupé.

Je n'ai pas accès au programme de la machine, je suis en contact avec l'ouvrière qui la pilote, mais à distance.  

Auriez-vous des éléments de réponse ?


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Hi !

New to LibreCAD, I use it to create patterns for leather, intended for a digital cutting plotter.
The plotter traces and then cuts each piece in the leather, using a dxf file.

I draw relatively simple 2D dxfs, with only one layer.

-1st problem: some parts have interior cuttout: the plotter simply ignores them (no tracing or cutting), and cut the outside only

-2nd problem: certain circular arcs/circles are not taken into account, but not all the time. Only two files are a problem: one circle of 85 mm in diameter (not even detected by the plotter), and another in which there is a circle's arc with a radius of 43.33 mm: here the arc is only drawn (and not cut), and offset from the rest of the part (which is not the case in the drawing).

I don't have access to the machine's program, I'm in contact with the worker who drives it, but remotely.


Can you help me ?



Merci ! THX !

Basically, this is an issue you should discuss with the plotter or post-processor manufacturer.
He knows the requirements and can better estimate whats wrong with the mentioned drawings.

Just a guess: Use the list plugin to get more info about the ignored entities.
E.g. select two entities, one which is cut and one which is ignored. Then see, if there are any differences.
I can imagine that the ignored entities are ellipses, elliptical arcs or splines. CNC controls don't like ellipses or splines, too complicated and too slow to calculate motor movements on the fly.

You can try to save the DXF in R12 format, which has no ellipse support. Ellipses are replaced by polyline approximations which might be accepted by the plotter.

Thanks for your answer !

That's what I thought, I asked to have contact with someone who knows the requirements for the plotter.
 
I didnt know the "list entities" tool, very useful, thanks.The ignored entities are basic circle or circle arcs, but I noticed with this tool their radius weren't "regular" (43.3454 mm...), it might explain the issue.

About the "inside cutting", entites are very basic: circles or rectangles. But I think it's linked to the requirements for the plotter...