Salut Jean-Paul,

Here is one try;

with a similar shape, I trimmed the solid using a 2d rectangle, then used offset on the inner shape (using the flip option).

Then joined the perimeter of the outside and inside shape and lofted them.

Hope this helps!


Marc

Hi Jean-Paul, yeah you will normally want to use Offset or Shell for things that have constant thickness.

The surface offset mechanism seems to be having a problem with your rounded tip part in this case, so that is making things a bit more complicated here.

Normally what you would want to do would be trim those panels but keep the surface fragment on the inside of the panel instead of throwing those away. Then you would use Shell to thicken that fragment into a solid of even thickness, then delete the outside surface of the shell and then join it to the outside part. But there seems to be a bug preventing the offset or shell from working on your revolved surface there. I'll try to take a look at what is going on with that.

- Michael

Here's how I do it.

1) Create a copy of the object and scale it down (You cannot see it in the picture)




In this example, I want to create a circle hole through the object. I create a circle.

2) Select the main object and boolean difference the circle. You can then see the smaller version of your object and it has the proper curvature



3) You can then shrink or grow your smaller version of the object and change the depth of the cut.





I'd love to hear from the pros on this, because I just KNOW that there is a better way.

Doh! Took too long to create my pictures. The pros have answered.

Hi Jean-Paul, it seems that your revolve has a bit of skew in it, probably that is not good for the offseter.

If I take a look at the edge of that revolved surface:



If I then zoom in to the top view of that edge and look at the back end, I can see that it is not aligned to the world axis line:



the front part of it is though. So it is either rotated or it twists slightly instead of being a simple world-aligned profile which is more what you'd want.

In fact, looking at it some more, it is just the one endpoint (the one at the back) that is off of the world axis, so that means it is not actually a planar profile, it has a slight twisted shape to it. I'll see if I can repair this for you which will probably make the surface offset work.

- Michael

Hi Jean-Paul, yeah it was that slightly twisted profile (it was bending just a little bit in 3D rather than being a flat planar profile) that was making the surface offset not work right there.

I've attached a tuned-up version where I used Transform/Align to get all the curve control points to be on the world plane.

This version should now work for you, I've left the pieces cut up so you can now select these fragments, which are from trimming but leaving the pieces behind.

So you want to select those fragments:



Run Construct / Offset / Shell to thicken them all into solids:



Now select the outside surface of these new solid pieces:



And delete it to make that open, leaving a kind of cavity structure:



Use Edit/Join to join those cavities to the outer structure to make the final result:




But I did just a quick job with re-using the old projected curves that were projected on to the slightly twisted surface, you'll probably want to actually re-do the projection of those on to the fixed up surface instead, to make sure all the things are aligned well.

- Michael

Hi Michael.

This is just splendid !

I'll get back to it tomorrow, but I am sure it will work now.

Thanks.

Jean-Paul