# Non-smooth curve and taper

I would like to make a bent cylinder with varying radius. Taper and Bevel seem like a good way to do this, however, I would prefer that the Taper curve is not a spline but a polyline, so that I can make sharp edges.

Ideally I would like it to be a profile function R(t).

EDIT: Below is an example of what I'm not really interested in. It should be a lot more... edgy...

• Looks like @lemon's, to me... the quick way to get a polyline curve is to convert a mesh to a curve.. so perhaps you could use a bit of my answer, too. (The slower way to make a polyline curve is, in Edit mode of a curve, with a spline selected, right-click menu > Set Spline Type.) Nov 9 '20 at 12:27

You can use a "screw modifier" instead of a taper object.

The first shape above is the selected edges with a screw on it.

Then it is curved (second and third objects below it).

Depending on what you want:

• The second also has a bevel and subdivision to keep sharp edges but follow the curve smoothly.

• The third only has a curve.

• Thanks! That is great. But how did you make the polyline? I can only make splines, when I choose Add->Curve->BezierCurve Nov 9 '20 at 11:51
• The "pseudo taper" is not a curve, but a mesh with edges only Nov 9 '20 at 11:52
• Though, you can screw a curve too. (and bevel/subdisivion modifier) Nov 9 '20 at 12:11

This is a 2D Polyline Taper curve, modifying the radius of Bezier curves:

Maybe The sharpness of your result is limited by the U resolution of the bevelled and tapered curve? That's set in the Data tab, Shape panel

As for the maths function, you could use Add > Mesh > Math Function > Z Surface, and set a function in one of X or Y (instead of both), Shift D duplicate out one of the mesh's profile edges, P separate it into a new object, rotate into the right orientation ( as illustrated ) to be a taper curve in Edit mode, and convert the mesh-edge to a curve.

I'm sure, in the past, I had to enable the shipped add-on Add Mesh: Extra Objects to get the math functions, but I don't think you have to, any more.

• Hi Robin... yes. Have seen it and so deleted the comment. Nov 9 '20 at 12:16
• @lemon all in all, I still think your way would be less of a pain, with a Curve modifier to do the bending.. Nov 9 '20 at 12:18