topic Invalid surface when trying to sweep in AutoCAD Forum

Invalid surface when trying to sweep

Anonymous — Sun, 10 Sep 2017 07:36:36 GMT

Hello,

I've got a problem with following file. I can't sweep my circle along the 3D Spline path, both by using SWEEP and EXTRUDE command. Translating my error message it more or less stands as "Dragging along the path creates an invalid surface". Anybody has an idea where the problem is?

See DWG attached.

Regards and thanks in advance,

TB.

Re: Invalid surface when trying to sweep

parkr4st — Sun, 10 Sep 2017 09:16:31 GMT

the circle will intersect itself. try a small circle about 1/4 size of yours and it will sweep or extrude

see this https://forums.autodesk.com/t5/autocad-forum/error-400212-during-sweeping-a-profile-over-a-helix/td-p/7196321

dave

Re: Invalid surface when trying to sweep

Johanna_Esteban — Wed, 13 Sep 2017 00:35:05 GMT

Hi.

Often, extruding using a spline as a guide or guide is a problem.

It is advisable to use 3DPOLY for this purpose, but, if the spline is already made, the solution is as follows.

Use the SPLINEDIT command, select the spline and in the command options choose CONVERT TO POLYLINE, to convert the spline to a polyline, precision 1 (this value can be changed according to the result you are looking for, the higher, the higher the number of points in the polyline).

You already have the 3DPOLY but every edition point you had in the spline has become an editing point for the polyline, it is now possible to make the extrude using the polyline as a pattern, but the extrude will have as many vertices as the polyline.

Correction: With the initial spline, modify or delete the points you do not need, so that when you convert to 3dpoly you do not have much to edit.
Convert the spline to polyline and extrude using the latter as a guide or pattern, you will see that the result is much better.

Make sure that the center of the circle to be extruded is positioned at the end of the polyline and, if possible, that it is perpendicular to the polyline for optimal results.

Please let me know if it was possible for you.

Greetings.

Re: Invalid surface when trying to sweep

leeminardi — Wed, 13 Sep 2017 02:28:29 GMT

You are using way too many Fit points to define the spline. I traced over your spline using OSNAP End and Near to create a spline close to your spline but with fewer Fit points. In doing so I took care to make sure the radius of curvature along the spline would not cause the sweep of the circle to self-intersect. Do not use a 3D Poly.

I then used the SWEEP command and your circle to yield the following:

Lee