# Can linear extrude twist elliptically instead of circularly?

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## Can linear extrude twist elliptically instead of circularly?

 I created a curve using linear_extrude of a circle, with the twist parameter and the resulting extrusion twists around an invisible cylinder. What I am looking to do is have the extrusion twist around an elliptical cylinder. I could scale after the linear_extrude, and while that does make the hole elliptical, it also stretches the extrusions, which I do not want. As you can see here, the left shape extrudes around a cylinder - on the right after using scale the hole becomes elliptical cylinder but the extrusions are stretched as well. What is the best way to accomplish this?
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## Re: Can linear extrude twist elliptically instead of circularly?

 If you scaled the linear_extrude with, say, [a,b,1], scale the circle before the linear_extrude with [1/a, 1/b].2016-07-03 3:51 GMT-03:00 NathanA :I created a curve using linear_extrude of a circle, with the twist parameter and the resulting extrusion twists around an invisible cylinder. What I am looking to do is have the extrusion twist around an elliptical cylinder. I could scale after the linear_extrude, and while that does make the hole elliptical, it also stretches the extrusions, which I do not want. As you can see here, the left shape extrudes around a cylinder - on the right after using scale the hole becomes elliptical cylinder but the extrusions are stretched as well. What is the best way to accomplish this? -- View this message in context: http://forum.openscad.org/Can-linear-extrude-twist-elliptically-instead-of-circularly-tp17868.html Sent from the OpenSCAD mailing list archive at Nabble.com. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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## Re: Can linear extrude twist elliptically instead of circularly?

 a = 3; b = 2; scale([a,b,1]) linear_extrude(40, twist=360) translate([2*a,0]) scale([1/a,1/b]) circle(5);
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## Re: Can linear extrude twist elliptically instead of circularly?

 That doesn't seem to work. Try changing a = 4 and b = 1: a = 4; b = 1; scale([a,b,1]) linear_extrude(40, twist=360) translate([2*a,0]) scale([1/a,1/b]) circle(5); The extrusion is not circular.
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## Re: Can linear extrude twist elliptically instead of circularly?

 Replace the translate by translate([a*b,0])2016-07-06 2:30 GMT-03:00 NathanA :That doesn't seem to work. Try changing a = 4 and b = 1: a = 4; b = 1; scale([a,b,1]) linear_extrude(40, twist=360) translate([2*a,0]) scale([1/a,1/b]) circle(5); The extrusion is not circular. -- View this message in context: http://forum.openscad.org/Can-linear-extrude-twist-elliptically-instead-of-circularly-tp17868p17885.html Sent from the OpenSCAD mailing list archive at Nabble.com. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
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## Re: Can linear extrude twist elliptically instead of circularly?

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## Re: Can linear extrude twist elliptically instead of circularly?

 In reply to this post by Ronaldo I checked it now. You are right, it does not work. But this do it with a lot more working time:a = 4;b = 1;c = 10;minkowski(){    scale([a,b,1]) linear_extrude(40, twist=360) translate([c,0]) circle(0.0001);    cylinder(r=5,h=0.0001);}2016-07-06 9:11 GMT-03:00 Ronaldo Persiano :Replace the translate by translate([a*b,0])2016-07-06 2:30 GMT-03:00 NathanA :That doesn't seem to work. Try changing a = 4 and b = 1: a = 4; b = 1; scale([a,b,1]) linear_extrude(40, twist=360) translate([2*a,0]) scale([1/a,1/b]) circle(5); The extrusion is not circular. -- View this message in context: http://forum.openscad.org/Can-linear-extrude-twist-elliptically-instead-of-circularly-tp17868p17885.html Sent from the OpenSCAD mailing list archive at Nabble.com. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org