Extrude Surface

something odd happens when I extrude the end surfaces of the solid in this file. I would expect that I would end up with another solid of the same height and width. However I only get a four sided open polysurface. Also the end surface that I extruded loses its isocurves.
The original solid was the BoundingBox of a irregular solid.

extrude.3dm (49.3 KB)

Which specific Extrude command are your running and where are you selecting it in the pull-down menus or toolbars?

When I use Extrude Surface - Straight from the Solid pull-down menu, I’m getting the correct results you described.

Check that Solid is on in the ExtrudeSrf command line options. I’m not seeing the absence of isocurves however, I used Rhino 5 for Windows SR11

@John_Brock I was using Extrude Face from the solid editing toolbar. As @BrianJ points out there is a Solid option which I missed, although I would have thought that in the solid editing toolbar Solid should be the default. But I should have checked the command line.

Here is a screen grab of the isocurve anomaly. It isn’t a problem, just strange. Thanks for your time!

you might like the command _MoveFace better for this scenario… (with direction set to ‘normal’)

(or sub-object select the face and use the Move command)

@jeff_hammond ,
I specifically wanted the extrusions to be separate entities. Doesn’t happen with MoveFace.

Personally I’d use the Gumball and sub-object modeling for this. The workflow would be:

  • Hold ctrl+shift and Left click the face you want to extrude… release ctrl+shift
  • Start moving the face with the gumball
  • tap Alt to make the result a copy but don’t release the left mouse yet
  • type a dimension and enter still with the left mouse held
  • finally Hold ctrl and release the left mouse

It may take a few times to get used to the process but it can be very fast and you’ll end up with individual solids.

Yes, @BrianJ, I should use Gumball more than I do. Trouble is that I’m an old dog, and it’s a new trick.

I was able to do it but perhaps I should ask about the steps:
-Ctrl+shift = sub-object selection?
-Move uses arrows? Actually that’s obvious!
-Alt = turns whatever operation you are performing into a copy? Not just move?
-Ctrl at the end of the operation = turns operation into a solid? From my experiments this only seems to work with move?

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Actually the only part that is unclear is the final control.

my bad… I misinterpretred what you’re attempting to do

Correct, cmd + shift if you’re using Rhino on the Mac.


Yes, it makes an extrusion. This works when moving a surface but will also work when rotating or scaling a curve. I generally only use it when moving objects.