Simple sweep2 failure why?


I have checked for intersections, as can be seen running intersect sees all lines intersect.

I have checked for direction, all lines ok, no opposing directions.

rail nearest me so to speak, had direction opposite to the other rail, so flipped that, made no difference.

What have I overlooked to check ?

rails and profiles, profiles are the straight line segments.

simple sweep2 failure.3dm (32.6 KB)

Hi Steve- apart from section curve placement, Simple is only available if the rail curves have exactly the same structure - in this case they are not… e.g:


all made very simply, drew a radiused circle 20mm and projected it to an angled planar surface giving an elipse shape, as such thats enough to cause failure.

so after projecting something, one needs to redraw it. (restructure it)…never knew that requirement, thanks.


I did that yesterday and surfaced just the corners ok. thought I would skin the entire lot in one go.

It networkSrf’s ok though. why is that ?

I do despair at times.

so its beyond sweep2 ability unless I redraw that projected result. ?


When you Project, if you use Loose=Yes, you will get the same structure - that is certainly valid when projecting onto planes but for more complex targets you need to be careful, especially if the curves have kinks or potential kinks like arcs, circles, and joined polycurves in general - for non planar targets the result of a loose projection may be well out of tolerance.


The fact that NetworkSrf worked, is that ok ?

or should I redo the projections and choose Loose=yes even if using NetworkSrf ?

why did NetworkSrf not fail ?

I saw circles as accurate items creating accurate results.


Hi Steve - was the initial complaint that you could not get a Sweep2 that allowed Simple Sweep, or that Sweep2 failed altogether - I assumed you were asking about Simple sweeps, but it looks like that is not the case… I see that it fails completely, I’ll dig in.


Hi, yes, sweep2 failed, I saw the structure as a simple creation, yet sweep2 failed and I am glad to see NetworkSrf worked, but why did sweep2 fail.

Should it fail on a projected circle making what it did, in a rail, I have drawn rails with all sorts of ingredients and not had sweep2 fail, go twisted yes, but show nothing after the options panel appears, a new one on me.


It does not like the lower bend on the projected curve there are four points very, very close together on the end of that curve - I cannot reproduce this, projecting your original to a plane…


Hi Steve,
It looks like you still don’t get how basic modeling works. You take the longest possible route thinking it’s a shortcut. And on top of that, when it’s sloppy it even harder to get clean and simple results.
When I see your curves, I see three planes with a fillet between them and an angled trim through it all.
Look at the file I join, each hidden layer show the step taken.
The planes defines by your curves where slightly not rectangular and I kept them this way, but I would double-check that; there’s a strong possibility that their edges should be perpendicular to each other.
simple is better.3dm (291.9 KB)