Help with making a shell for this kind of surface

Hi! I’ve measured this surface from a real-world detail and now need to make a shell for it, make an inner extrude with 2 mm of thickness. But I’m not sure how to do it having a clean geometry after that and all the measured angles staying the same and having an ability to make some edges rounded after extruding. Could someone please share your step by step workflow for this kind of job? Thanks!

I’ve attached my .skp model with this flat surface.
shell.skp (210.2 КБ)

Select all the geometry.

Use the Fredo6 extension Joint PushPull.
Select all with the component open for editing (why is it ‘double wrapped’ as a component within a component?)
Start JPP and drag inwards.
Type 2mm (it will enter in the Measurement box).
Press Enter to start the extrusion.

That gets the shell 2mm thick. Or should. But I got an error and the extension didn’t work.
Tried again using the Thickener option.
That ran to completion, but didn’t work properly either, but looks as though it might be fixable.

I’ve done that, and saved the result here:
shell.skp (436.5 KB)

Until I copied your model into one with a plainer style, I just couldn’t see whether the initial result had worked.
Can you tell from this view? And that’s after I had set the view to Monochrome. Maybe you are used to this colour scheme? Or it’s in Dark mode, which I have neither used nor seen before?

Looking again, and assuming that black is a front face, and purple a back face, then I can begin to see the problems.

Compare with this:

I can see more easily here that it hasn’t worked well.

Open the component for editing, and Move/Copy the bottom face up to the top, reverse faces, and delete the excess lines that are in plane.
Sorry, it’s late, and I haven’t time to see if that works except for briefly trying it on the bottom face.

To round the edges, use Fredo Corner extension.
Both extensions need you also to install FredoLib.

To round edges, select them, then start Fredo Corner, specify the rounding radius and number of segments in the round.

To make that bit work, you might do better to use the Dave Method (search this forum for it) and scale up a copy x 1000 first, Zoom Extents, then work on the scaled up copy before deleting the large copy, and use Zoom Extents to see the result in the original.

I’ve left that for you as I don’t know how fine to make the segmentation. I did try it briefly on the marked edges, using 0.5mm offset and 2 segments. It seemed to work, but you will want to fix the Joint Push Pull operation first, I think.

This is my own style I’m working with. BTW it can be seen here in each style what color for what side.

But the problem here is not the faces are reversed the problem is that no surfaces were created in these places. So I made some video screen to show how I tried to extrude this in different ways but no success so that’s why I’d like to see what other users would do in such a case and what is the most optimal way.

I’ve uploaded screen video here

Well, I don’t know why Joint Push Pull won’t work.

But I found that ordinary push pull will do a good enough job, without using the Dave method. Although even that has an oddity in this model - on many of the faces, the operation doesn’t leave the original face behind, but deletes it.

Use the Ctrl key modifier so that Push Pull is forced to create a new face and leave the old one.

Use it on every face in the model in turn.

Clean up reversed faces.

When done, select all (either Ctrl+A , or triple click with the component open for editing).

Then Intersect Faces with Selection to create the join lines where inner faces intersect, use Solid Inspector 2 to remove internal faces, and clean up manually. I found it helpful to work in X-ray face style to see and delete using the Eraser tool short internal lines that were formed by the intersect faces command.

Here’s where I got to with just a few minutes clean up.

Shell thickened and cleaned up.skp (355.4 KB)

The horizontal lugs at the top still need a little bit of work, and the near bottom face might need to be redrawn, depending how you want the corner joins to look.

thanks. but maybe @DaveR also look at this topic and say his opinion

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I temporarily removed the piercings on the bottom face as well as those L-shaped ones on the sides. Then I used Joint Push/Pull to give the thickness. I did some rounding and made sure I had a solid component. Then I made cutter shapes for the holes and made sure they created a solid component, too. Then I used Trim from Eneroth Solid Tools to cut the openings.

There are some places around the bends that I think need some attention. They aren’t all that pretty as is.

I did use the Dave Method although maybe it wasn’t required. Better safe than sorry.

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could you please share .skp file so I could inspect the results closer?

Sorry. Since John uploaded his version, I didn’t save what I did. There’s nothing wrong with John’s methods or the results he got.


There’s almost always more than one way to achieve a given result in SU, as @DaveR has illustrated beautifully.

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