This seems fairly straightforward, but I'm having some problems closing this to a solid.
1. Sweep Rail
2. Sweep curve
3. Sweeped surface generated by 1 and 2
4. Planar top

And now I want to close the back (which you see is open). There are very tiny curves in the corner-- I've selected them and tried PLANAR on them and it works, but they cannot be joined to form a complete solid. Any idea why not OR how to fix?

More easy if you link your file 3dm! ;)

Hi Chipp - sweep does not really expect for a piece of the sweep to pivot around a single side point like the corner areas in your profile curve will require.

If you zoom in on the those "pole" corner areas you will probably see that the surface is likely a little weird and maybe has little zig-zags or wobbles in it.

Sweep is only really expecting to make segments where the surface does not bunch up on itself on the sides like that. So you can't really use sweep to do that quite in that way.

Probably the best way to get the result you want is to make a solid box to start with and then select these edges of the box and do a fillet:






Usually those kinds of partial sphere corner type areas should be done by filleting.

- Michael

oops. I thought I did upload the file. Apparently not:
here it is...

https://altuit.cloud/web/dbpub/3D/NextBook03.3dm

Yes, Michael, thanks for that, but the surface needs to be exact, and the fillet won't do. See the model:
https://altuit.cloud/web/dbpub/3D/NextBook03.3dm

And FWIW, the sweep did not go around a cornered rail, but rather a radiused one. (See dot 1)

The corners are perfect little radiuses. The profile must be exact as this solid will be subtracted from a design to form a cavity, which will then be NC milled to create a perfect fit for THIS android tablet model.

Perhaps I need to separate it in quarters?

OK. I figured it out. Here's what I did.

1. After SWEEP, this small curve was generated at each corner. I then QUARTERED the model and threw away 3 of the quarters.
2. I constructed small lines to enclose the curve (co-planar to back surface) and then built out the long slim surfaces to boundary the pie shaped slice.
3. I then created the rest of the back using the straight lines from the slim surfaces. Joined everything and checked for 'leaks' (N key) and it was all good. So I mirrored and joined and voilà, a Solid!



File:
https://altuit.cloud/web/dbpub/3D/NextBook05.3dm

Hi Chipp, sorry yeah just going by your image above and not the 3DM file I thought that your corners were exactly the same radius as the size of the profile curve, making things pinched to an exact single point on one side. But with your upload I can see that there is a little space in there so you should be ok.

Your file is all set to be made into a solid, just delete the bottom face that you had previously built so that you only have the sweep, then select the sweep and run the Construct > Planar command. That will build end caps on the planar openings of the object and join them in automatically so you'll have a solid as the result after running just that one command.

The Construct > Planar command can work in 2 different ways, you can give it a set of planar curves to build a planar surface from (in which case you will need to also additionally join the pieces together with Edit > Join afterwards), or the second way to use Construct > Planar is to give it a surface object that has open edges in it and it will find sets of open edges that are planar, build planar faces out of them, and join them together all in one go which is pretty convenient.

So anyway the upshot is to just run the Construct > Planar command when you finish your sweep and that will get you the result you need I think.

- Michael

Hi Chipp, I'm glad you got it finished!

See my post above for a quicker way - all you need to do is select your sweep and then run the Construct > Planar command. That then automatically finds closed sets of naked edges that are planar, builds planar surfaces in those spots with those edge curves being the boundaries, and also joins the pieces together for you. So you should get a closed solid just after selecting your sweep and running that one command.

- Michael

Thanks Michael. Didn't know about the 2nd way to use Construct > Planar. Helpful!