Problem with Extrude from Object

[steve.fritzinger]

I'm having trouble with Extrude from Object. I'm trying to model this helmet so I can carving it on my CNC router.

I created a simplified version of the helmet to test with.

I also made a sketch of the "star" and the hole for the face.

Here's the problem. When I try to extrude the star from the surface of the helmet, I can't select the entire star profile. I have to break it into two parts, one for the dome and one for the tapering sides, and extrude them separately.  The same goes for when I try to push the face into the helmet.

Doing the extrudes in four separate operations sort of works, but it's inconvenient and it leaves an odd artifact in the star where the part extruded from the dome meets the part extruded from the taper.



Am I doing something wrong?  Is there a better way to accomplish this?

Here's the exported design.  Thanks. 

[ryan.bales · Accepted solution]

That is mostly due to the sketch profile of the revolve. Making the splines tangent should clean up that point: 

Typically i'd suggest emboss here, but it doesn't pick up faces created via splines very well (or at all in some cases) 

[steve.fritzinger]

Thanks, Ryan.

That worked on my simplified form.  The real plan is to model the helmet as a quadball.  Extrude works for that, too. But having to divide my sketch up for each face on the ball and doing separate extrudes is a bit painful.

Emboss doesn't work at all.  It won't let me select a face from a quadball.

[g-andresen]

Hi,

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@ryan.bales  schrieb:

Typically i'd suggest emboss here, but it doesn't pick up faces created via splines very well (or at all in some cases) 

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Emboss is not possible on multiple curved surfaces.

günther

[ryan.bales]

I think that is true in part - its more like it cannot do multiple faces (though it does say 'faces'. I imagine there might be a situation it does do more than one but i've yet to see it.) Curved faces or straight edges don't seem make a difference for multiples. But curved faces do not work (or least i don't get them too). This isn't very technical and i'll admit i'm being reductionistic.

[jeff_strater]

The problem here is that From Object is missing two features which To Object has:  The ability to chain or extend faces, and the ability to select an entire body as the From Object:

This is on our list to fix, but has not gotten implemented yet.  There are other workarounds, but they are not much better, TBH - use To Object Extrude, then create an offset face from the helmet to  trim off the excess material.  Not a whole lot better than multiple extrudes, I guess