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I want to rotate a NURBS curve control points. On it there is a plane following de curve. If I tilt the control point for example to 90 degree, it rotates like to 80 degree. And to set it like 90 I have to put it to 140 degree. With bezier curves there's no problem. I put 90 degree to tilt bezier and it tilts exactly 90.

Here the NURBS curves tilt images trying to rotate 90 degree but looks like 80

here a frontal view

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  • $\begingroup$ Hello and welcome to Blender.SE! I can't see a direct connection to Geonetry Nodes here, and it's not clear what exactly you're trying to do (a screenshot of your node tree would be helpful), but basically you'd have to use the node Set Curve Normal to align the normals of the points all to Z Up first to get absolute values relative to the global axis. $\endgroup$
    – quellenform
    Jul 16, 2023 at 9:56
  • $\begingroup$ thanks, i put other two images on the post for better xplanation. How i can do this? "you'd have to use the node Set Curve Normal to align the normals of the points all to Z Up first to get absolute values relative to the global axis" $\endgroup$
    – Albert
    Jul 16, 2023 at 10:51
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    $\begingroup$ Are you using a Geometry Nodes modifier here at all, or not? If yes, then please show us a screenshot of your current node tree. If not, then take a closer look at the value for "Twist Method" in the Object Data Properties of the curve. $\endgroup$
    – quellenform
    Jul 16, 2023 at 10:58
  • $\begingroup$ sorry, I don't know how to import .blend here to check it. Basically i only did what is on the picture on top of post. Straight nurbs curve, with 7 control points. Added array modifier and curve modifier. Selected one of the middle nodes on the curve and tilted to 90 degree. And happens that tilts like 80 degree $\endgroup$
    – Albert
    Jul 16, 2023 at 15:11
  • $\begingroup$ I took the liberty of removing the geometry-nodes tag, since you're obviously not working with Geometry Nodes here. Please complete your question with the necessary information. You can also upload your blend file via blend-exchange.com and add the link generated there to your question. $\endgroup$
    – quellenform
    Jul 16, 2023 at 16:02

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This is perfectly normal behavior of a NURBS curve because it consists of control points and the values for Tilt assigned to them are interpolated when resampling and converting to a mesh.

A value of $90°$ becomes a value of exactly $60°$ and to get an angle of $90°$ you would have to set the Tilt to $135°$.

If you need the exact tilt values of the points, you would have to use a Bézier curve instead, where only the intermediate points are interpolated.

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