How to use geometry from a Body in a Sketch?

[ideasvacuum]

I used the 'Create an edge linked to an external geometry' function, but the entities do not count as Sketch entities - Solver says 'Empty Sketch'. I want to extrude those edges - how do I toggle them to Sketch Entities? Or is it possible to simply select the edges in Model Space for extrusion?

[Shalmeneser]

You need to draw normal lines using your externals geometries.
No automatic tool in master branch.

B-spline ??

[drmacro]

You trace over the lines with the various Sketcher tools.

[heda]

I think you will make it now,
not sure if you for example make use of the wiki or not.

does not matter so much, my question is if you go through Sketcher_External would you have caught on to the fact that you actually have to make all new geometry?

[thomas-neemann]

... how do I toggle them to Sketch Entities? ..

here is a possibility from min 0:06 (realthunder version https://github.com/realthunder/FreeCAD_ ... 3/releases )

https://www.youtube.com/watch?v=pNMkPZTty5w

phpBB [video]

[TheMarkster]

You can try to convert the external geometry to bsplines.

[chrisb]

You can try to convert the external geometry to bsplines.

This is indeed possible, but you should be aware of the consequences: If you create a pad from such sketch, the correspionding faces will be B-spline surfaces, and not planes, if you reference the sketch with external geometry, you will not be able to place points on it.

Just out of interest I would enjoy an answer to Shalmeneser's question above: Why do you use the uncommon B-splines in the corners and not simple arcs?

[TheMarkster]

You can try to convert the external geometry to bsplines.

This is indeed possible, but you should be aware of the consequences: If you create a pad from such sketch, the correspionding faces will be B-spline surfaces, and not planes, if you reference the sketch with external geometry, you will not be able to place points on it.

Another limitation is it will not be parametric to the external geometry. I doubt the convert to bspline tool was intended to be used with external geometry and as a happy accident it seems to work much of the time. Once converted the external links can be deleted without effect.

[chrisb]

Another limitation is it will not be parametric to the external geometry.

Excellent point! That makes this technique of turning external geomtry into real almost useless.

[TheMarkster]

Another limitation is it will not be parametric to the external geometry.

Excellent point! That makes this technique of turning external geomtry into real almost useless.

You can't really make bsplines in the sketcher that run through given points. The bsplines in the sketcher have control points that can be dragged to shape the bspline, but it doesn't go through those points. Such bsplines can be created outside the sketcher and brought into a sketch with this method.