How to offset surface


I draw this wheelpant, on the picture below it is a surface.

I would like to make it a solid object with wall thickness , let’s say 1.5mm.
I select the surfaces , type offset surface, flipp ( all the arrows to the inside , since I want the outside as I have drawn it) 1.5mm > enter>

It seems to be OK , but when I checked the rear part , it made a wierd thingy , which I understand why it made , since the surface needed to go through the other surface, since it is now 1.5mm thick.

How can I change this? It seems I can not do a offsetsurface to the inside since that point will always try to go through the otherside of the surface.

I tried not to “flip all”, but than something goed wrong with the surfaces when I import the stl file in the simplify3d slicer:

Anyone knows how I can solve this?
Many thanks,
hull3dm_smaller_met wielgat.3dm (221.5 KB)

Hi Cor - you’ll need to be sure that the radius of your surface is larger than the offset distance. That would mean making a transition surface between at the trailing edge, I guess:


Hello Pascal ,

Thanks for your answer.

I see , and I also understand why. I only don’t know how yet.

I deleted the surface , and made a circle like your red one, but now the verticals don’t intersect with the horizontals. That means I won’t be able to do a sweep 2 rails and make a nice round surface.

Offcource I can redraw the whole thing, make the vertical lines much higer and than round them off so the intersect the horizontals.
But is there an easier way?

If I decide to “don;t flip all” and make the offsetsurface on the outer side. how can I find out why and how something is wrong with the stl file: it show this wierd blue line:

Many thanks,

Hi Cor - I don’t see the existing surfaces in the file but I’d think about making a cap surface that looks something like this:

But fat enough that it can offset, I think mine is a lttle too small still.

NetworkSrf from your curves up to the last corss-section and my little cap surface added:

You can probably do it all in one network surface, you just need to make the sharp end curves come together smoothly at a fat enough radius.


Hi Pascal,

Thanks for your time. I found a command “cap” is that the one you are using? but how , it asks me to select polysurfaces.

I take that rhino file from the first post.
make the vertical line nice and round ( your red line)
But than, how would I proceed?
Does the red and blue line needs to intersect?


Hi Cor - make your curves like this:



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Cool , yes. I rebuild he wheelpant , now with more round curves, and I could do the whole stuff with networksurface in one go!.

Many thanks for your assistance.

Best regards,