Offset surface is wonky :/

I want the offset to be as planar as possible on the open edges/ holes at either end, and its veering off at one side.

Is there any way to constrain this? I cant just trim it after, because im making the corners of the projection curve rounded.

Bat Gauntlet refit to art.3dm (470.6 KB)

Thank you.

I have tried rebuilding the network curves and the network surface to no avail, so im assuming its the shape which is doing this. Are there any other tools I can use to make an offset?

Hi Simon,

Are you able to give a little more detail?


if you want the edges/surface to offset towards one direction only, you can use _ExtrudeSrf or _Copy
that said, i imagine these will also give you undesired results as the distance between the two surfaces won’t be consistent unless the surface is flat to begin with.

as a way to better understand/visualize what OffsetSrf is doing, maybe try the command on a cylinder and a sphere… what it does to those is the same thing it’s doing to your surface.

Blimey that was quick :slight_smile:

I want the open end on the right (the smaller piece) to be pointing directly away from the orig surface and not diagonal when I offset (or as close as possible)
The end circumference of the base tube shape is planar and a single surface, so im not sure why one side is veering off (bottom right of top left picture).

Doesnt need to be a solid as I can rail that after.

If only I could tweak those normal lines (I assume thats what they are) Like handles.

i don’t think it’s veering off… when you offset the surface, it moves in the direction exactly perpendicular to points on the original surface… the arrow you’ve circled signifies the ‘normal’ direction of the surface at that point and you can see it’s moving at a 90º angle.

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Exactly correct. So, go to the top view and trim your offset surface back. I’d make a straight line right above the open end and use that.

This is a technique we practice in my Rhino class. We call “Make it bigger & THEN trim it back.” Catchy, eh?

But, it actually makes your job easier as you no longer have to make a surface EXACTLY to another boundary … which, you can see, frequently fails.

hey Simon… i recorded a method which you can use to tweak the surface pretty quickly without sacrificing too much precision on this particular shape:

it’s rhino for mac but all the commands will be the same on windows as well.

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Thats a good workaround. Thank you for taking the time to make that.