Export to .sat and .dwg/dxf fails

Hi - could someone please help me out what is wrong with this geometry?

It does not show up in exported files (.sat,.dwg/dxf etc)
I can “select export” it from the original file, in 3dm, and open it in Rhino.

But no such luck in AutoCad Robot, etc.

I have put quite a bit of work into this one, so I would be glad to know how to export it to .sat (ACIS) and .dwg ?

I have done other, similar geometries, with the same workflow and techniques (flowalongsurface).
They where simpler in size and complexity, and I had no problems with those …

So… what is wrong with this one?

thankyou very much

Hans Henrik

SCULPTURE- surface CW.3dm (1.4 MB)

Try STEP if the target you are exporting to can read .stp.

Hi Hans- the large outer surface is ‘bad’. I would extract this surface, UntrimAll and then re-trim the holes.

You can locate the bad edge by

  • ExtractSrf the outer surface
  • Hide everything else
  • Start UntrimAll with KeepTrimObjects=Yes
  • Hide the surface
  • SelBadObjects will select the curve from the bad edge.

How were the smaller surfaces made?

@ohlers, I cleaned up the object - the problem was at the location where the blue arrow is pointing in the attached file - there was a tiny sliver of the main surface trimmed out and joined to the blend-like surface there. I deleted the little extra surface and retrimmed that hole with the edge of the blend-like surface.

SCULPTURE- surface CW_PG.3dm (1.6 MB)


Hi Pascal

thankyou very much for speedy response ! :smile:

You mean the holes with the double-curvature edges?
I did FlowAlongSurface , with an arrangement of base-curves(rails) and sweep2/closed sweep surfaces.
I nudged these base-curves on the flat plane, using history, and shaped all the holes, until they looked nice on the sculpture surface.
After flowing the objects along the surface of the sculpture, I used the flowed base-curves to split holes in the sculpture surface, and deleting the cut-out pieces of surface.
after that, I JoinEdged all naked edges. Do you understand this?

How is an object “bad” ? (edges, surfaces, curves etc )

I had some trouble with one hole in particular, that for some reason was “cut out” leaving a lot of small lines at the edge.
I have no Idea how that happened, and ended up just zooming in really close and JoinEdged small bits of edge.
Is that the culprit?

Will the solution you suggest delete the bad surface, or fix it?

I am wondering if there is a better workflow, so I avoid anything “bad” happening ? :smile:
perhaps making a flat, rectangular surface first, cut all the holes and attach (JoinEdge) all the smaller surfaces, and then flow this object along the surface of the sculpture ?

I need to export to .sat files, so I can open the project directly in AutoDesk Robot for FEA analysis.
This makes a nice workflow with the engineers…


Hans Henrik

Hi again - sorry, I overlooked that you have actually fixed it !

Yes thats excactly the hole with the weird lines from trim (split)

Thanks !!!

Ill practise your repair-sequence !

Have you any idea how this happened?


Hi Hans- the workflow seems reasonable, - I think what may have gone wrong is in the trimming part- somehow there was a sliver cut out of the larger surface and joined to the flowed surface in one location and this tiny surface was only .002 units wide, well below your file tolerance of .01 units- that is not good. At any rate, I would certainly fix the object as I outlined above rather than start over, but I think I’d model from the start at .001 tolerance- your flowed surfaces are about 0.18 units wide and that is getting uncomfortably close to the file tolerance of .01- I’d shoot for any ‘features’ being at least 10X tolerance in any dimension- preferably more than that.


Avoid using JoinEdge (http://docs.mcneel.com/rhino/5/help/en-us/commands/joinedge.htm )

rather, use MatchSrf and Join if Join does not work at first - if your surfaces are not trimmed, as in this case


Cool, thanks

FYI - I exported your 3dm file to .sat (ACIS), and tried opening it in AutoDesk Robot, but it is crashing Robot…
So, I´d probably start over, right? - adjusting the tolerance… matching surfaces…

allright, keep learning ! :smile:


Hi Hans- before starting over , I would

  • Explode and UntrimAll all of the surfaces.
  • Set tolerances to .001.
  • trim the holes using the edges of the now untrimmed smaller surfaces.
  • Join each and if they do not Join MatchSrf for Tangency - if they still do not join, check the box for ‘refine’ in matchSrf and try again.

Any luck?


I did Explode, and UntrimAll + untrim each individual smaller surfaces
set the tolerance to 0,001, and trying to trim, using the edges of the untrimmed smaller surfaces…

But the trim part does not bite…

its like the objects are not intersecting with the main surface…

any tricks?

are you using the surfaces as a whole to trim with or the edge curves? My guess is the surfaces will not trim in at least some cases, but the edge curves should, so start Trim, with no selection, and then type in

crv and Enter

this filters the trimming object selection to curves only, including edge curves (you could also dupEdge ahead of time ad simply use these curves with no filter). Then with an edge selected, Enter and click in the middle of the curve to trim the surface there.

The advantage is that the surface-surface intersection does not come into it this way, the curves used is simply pulled onto the surface to make the trim.


uuuh - sexy ! its like popping soap-bubbles ! :smile:
in other words - it works !

wow what a cool workflow ! and a neat trick with the crv command

  • Rhino is awesome…absolutely awesome !!

What is the difference betw splitting and trimming?

thanks a lot for this !


Splitting leaves all pieces in place, Trim removes the bits you click on. BTW, on surfaces, trimming does not remove anything, it only hides it, which is why you can Untrim.


cool - i just tried crv - selecting all edges, and started to pop holes, but then the big surface dissapears - maybe too many cutting objects?

Hmm - the main surface disappears also with only a few curves selected for trim… is this a bug?

Not sure- it may be that the click point on the surface is not where you think it is. See if you can narrow it down to one curve that does it- feel free to post it and the surface for a look.


Its ok, I just have to be a bit patient and only select a limited amount of curves to trim with - then it works like a charm :smile:

Thanks again fro a really cool command !

could it be a lack of RAM? I have only 4 GB on this iMac…

so - all surfaces are now joined - remarkably simple and cool -
and the .sat export opens fine in Robot - how do you like them apples now, eh ? :slight_smile:

You have totally saved my day ! thanks !!

SCULPTURE- surface CW_PG.3dm (2.4 MB)

OK! Good deal, I’m glad it all worked out.