Hi Michael, I can't seem to find the source object in the .3dm file you posted. Can you please post one with just the base object and path for the array alone and not just the result of the array?

If the path is planar then I would think you should be able to create offset curves from the path to form boundary curves. You'd offset the path through a vertex of the base object and then move it to the z level of the vertex.

But also like you mention a one rail sweep of edges of the base object should generate some surface pieces as well.

- Michael

Hi Michael, sorry, I got my attachments mixed up.

In the new file, source solid and path. In addition, as you proposed, offset curves (for four coplanar vertices).

I swept the corresponding edges along the offset curves (default settings), merged the resulting faces and deleted the "behind" faces. The boolean result looks very clean this time.

- Michael H

Hi Michael H - that's looking pretty good! Will that method work for what you need?

I guess it would be good to overlay it onto the dense array to check it for accuracy. I think that possibly doing extensions of the offset curves may cause a little bit of differences in shape from the array result.

I think that maybe a way to get a really accurate result you may want to connect a line to the start of the path curve (the original path curve, no offsets) for each edge that you want to sweep, so that profile for the sweep will have its initial position at the start of the path curve rather than it possibly attaching to the interior of the path curve.

What I mean is to sweep this edge:



Extract it into a regular curve by selecting it and doing Copy/Paste (Ctrl+C/Ctrl+V) and then draw a line connecting it to the start of the path and join it so it's like an L shape like this:



Now sweep that joined L shape with the path as the single rail and it should give you the right shape:



You can delete the extra face generated by the other piece of the L.

The reason for this is because if you just sweep the edge directly it's going to associate it with the rail like this:




Sweep works like that because you can make a sweep profile that is somewhere in the middle of the rail, like this:





By making the L to make the profile touch the start of the rail that will ensure that the profile will have the start of the rail as its station like you want.

Array curve is a little different than sweep in this regard, it doesn't try to make the profile connect to the middle of the rail like sweep does, unless the rail is a closed curve.

To make sweep behave the same as array curve you need to make the profile curve actually touch the start of the rail or be a planar curve where the plane touches the start of the rail. Adding the line to make the "L" shape does that.

- Michael G

So if you repeat that with all 12 edges you'll get surfaces like the attached.

It still needs some problematic bunching and slivery intersections to resolve but it's 12 surfaces to work with instead of a whole lot of arrayed solids so probably better.

If some extra space is ok maybe something like arraying a cutting plane along the path and intersecting those with the 12 surfaces could yield some cross sections.

- MIchael

Great suggestions! With the first example, I failed to trim about 10% of the surfaces.
I finally succeeded with a simpler case: the source solid is a tetrahedron, and the path curvature is smoother.
The trim tool ultimately worked better than the boolean merge, so I might go back and try that on the first example.

the resulting solid:


overlayed with arrray:


the tetrahedron "engraving" into a substrate: