topic Re: Converting 2D Sketch to 3D Model in AutoCAD Forum

Converting 2D Sketch to 3D Model

lothian_mcadam — Fri, 05 Feb 2021 19:40:19 GMT

I'm transitioning to AutoCad 2021 from another modeling software. My expectation with AutoCad is to use it in a similar manner: model 3D objects from 2D plans. In the interest of killing two birds, I'm attempting to learn this software while modeling things I need models of.

I choose the most intuitive course: I create a 2D shape using lines, arcs and splines, then JOIN all the bits to create a single, closed polyline 2D object. This object extrudes but the extrusion lacks faces on its opposite ends, and I can't figure out how to create faces. (The modeling software I'm migrating from automatically creates faces from closed shapes.)

There's probably a crazy-simple answer to my dilemma, but I cannot figure it out intuitively or find clear instructions online. Instructions, please.

Re: Converting 2D Sketch to 3D Model

Patchy — Fri, 05 Feb 2021 19:36:07 GMT

After extrude command, look for the prompt mode, choose solid instead of surface.

Re: Converting 2D Sketch to 3D Model

lothian_mcadam — Fri, 05 Feb 2021 20:16:49 GMT

Extrude> Mode> Solid > (select object)> Height

Exactly what I've tried a bazillion times already--always get the same result: no faces on opposite ends. ('Presspull' command also doesn't create faces.)

I'm convinced the problem is with the 2D shapes I created: each behaves the same way.

Re: Converting 2D Sketch to 3D Model

Patchy — Fri, 05 Feb 2021 20:24:48 GMT

Select the polyline, hit CTRL and number 1 (Properties pallet) choose closed, yes

then extrude or presspull and see.

Re: Converting 2D Sketch to 3D Model

leeminardi — Fri, 05 Feb 2021 20:40:49 GMT

I prefer to convert the 2D shape to a region and then extrude the region.

On a separate note, the solid white areas of your extrusion indicate an excessive number of vertices. How did you construct these segments which I assume are splines? You should only need a few fit points for each spline.

Re: Converting 2D Sketch to 3D Model

lothian_mcadam — Fri, 05 Feb 2021 20:51:39 GMT

good catch.

e'yup... i went a wee bonkers with the segments value on the spline.

Re: Converting 2D Sketch to 3D Model

lothian_mcadam — Fri, 05 Feb 2021 20:55:18 GMT

10 point to Gryffindor!

That was it. Thanks.

Re: Converting 2D Sketch to 3D Model

leeminardi — Fri, 05 Feb 2021 21:57:15 GMT

By "segments" do you mean fit points? A general rule is to use as few fit points, or CVs, as possible. As you increase the number of points that you use to define as spline you increase the likelihood of unwanted ripples and too much data is rarely a good thing. For the splines I see 4 or 5 points should be sufficient, surely less than 10 will give you the shape you need.