Curves and Circles in Sketchup - not suitable for CNC
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SketchUp exports 2d DWG/DXF arcs/circles as bits of lines - segmented curves [as 'polylines'].
BUT if you export a SKP as 3d DWG/DXF then arcs and curves are real CAD arcs/curves with NO segmentation...
AND 3d will also keep layering etc... -
Thank you, TIG!
This is big, big news to me. It has just saved me tons of work that I have always regretted having to do. I had never thought to try this. I am now the hero of the office! Yay! -
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@unknownuser said:
BUT if you export a SKP as 3d DWG/DXF then arcs and curves are real CAD arcs/curves with NO segmentation...
This is valuable also for circles ?
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@pilou said:
This is valuable also for circles ?
yes. very valuable for su Arcs and Circles.
su 'curves' don't transfer as well. they will export as polylines which can then be rebuilt or interpolated into smooth curves (depending on the application)
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And last question for be sure, result is "real circle" or SU "polygon circle" ?
(sorry I have not Pro version for test it) -
@pilou said:
And last question for be sure, result is "real circle" or SU "polygon circle" ?
(sorry I have not Pro version for test it)Real circles..
here's a sketchup drawing with a circle, arc, and a B-Spline (fredo) :
i exported as .dwg then imported into rhino:
so, the b-spline or other welded 'curves' don't translate as true curves via .dwg but circles and arc do.
.
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Many thx: now all is really clear!
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@tig said:
SketchUp exports 2d DWG/DXF arcs/circles as bits of lines - segmented curves [as 'polylines'].
BUT if you export a SKP as 3d DWG/DXF then arcs and curves are real CAD arcs/curves with NO segmentation...
AND 3d will also keep layering etc...Would have loved to have known that when I was exporting to autocad to do my drafting. Now I'm using Layout sooo...
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@TIG, This is indeed good news however I am running Sketchup8, pro version and when I export to 3D dxf with the intent to waterjet cut, we see both the segments and the true circle - meaning we still have to modify the dxf so its acceptable to the waterjet software (running a version of Mastercam). Is this a version issue or just an artifact of the 3D export to dxf? Note: setting parallel projection and standard view "top". Thanks in advance!
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If all you actually want is a 'flat' 2d object made from lines and true arcs/circles, then you need to copy your SKP, then edit it - looking 'edge on' using a selection by fence, so the unwanted faceted 'sides' etc, and top face of the form can be deleted.
Now you should have a 'flat' 2d set of geometry.
If your cutter doesn't need faces you can delete those too.
Now you should have a set of lines, arcs and circles.
Export those as the 3d DXF and you should then just get the paths you want...
Do not use a 2d DXF as that does NOT keep arcs/circles but makes them out of segments...
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