Sweep Accordion Pleats

I have frequently seen videos saying only beginners use NetworkSrf and Real pros use Sweep2.

A problem I frequently encounter with Sweep2 is accordion pleats.

Here is an example where I have loft, sweep2, and networksrf of the same curves (which are in the file) The side radius is constant and the upper are lower curves are faired.

Yet the sweep version is full of pleats (and unusable).

Why is Sweep so far off?

Problem Sweep 2.zip (425.2 KB)

I find that Sweep2 often makes problematic surfaces as well, and don’t really recommend it personally for most surfacing. The bigger issue here though is that you’ve combined lots of surfaces into one. I’d suggest thinking about this as three big main simple surfaces, with two blends between them. I’ve rebuilt it as such and attached it. I rebuilt the borders of what should be the “flat” areas, lofted those curves to make the 3 “flat” sides of your model, and then made blends (tangent) using BlendSrf between them. Built this way you can edit or change your model easily without going back to your curves, and the quality tends to be higher.

ProblemSweep Alternate Solution.3dm (2.8 MB)

Also, there is generally no reason to give any surfacing tool quite that many cross sections - I’d always give any of these tools the fewest possible to get your shape. That may apply especially to Sweep2 , but in general over defining is a recipe for wiggles.


I start with them all and pare back when I figure out what I need to join to the other parts.

It seems odd to me that, with apparently small curves and uniform radius, that I would get accordion pleats here. But I get accordion pleats all the time with Sweep2 (unless I only use 2 profile curves).

I added, that even with the frame reduced by 1/8" the accordion pleats are still visible.

Yeah, I see that - there is something odd with this set of curves - it does not look right to me either… I’ll get this on the pile, thanks.