Hi Alex, ok so I'm understanding a couple of things better - in that file you posted
you've got the MOI generated pipe in red and the SolidWorks pipe in green.

I wasn't quite understanding that part before.


> I have had a look at both solids in Rhino and there is differences on how the the solid shape is created.

Yes it looks like the main difference is that SolidWorks generates parts of the sweep using a trimmed torus
or cylinder analytic surface when it's possible to do so, while MOI's sweep always makes a fitted surface
using the general purpose sweep refinement process.

For example the first section starting from the outside has surface control points like this from MOI's sweep:


While the SolidWorks first section has control points like this - it's a trimmed piece of a torus:


- Michael

So basically they're structured pretty differently from when the sweep is generated, and then the STEP file generated from that will inherit those differences like the SolidWorks STEP file probably has torus surface entities in it.

Although they are structured differently, they are very closely describing the same shape. I made a very highly refined mesh to get a better visual without display artifacts and they are very closely overlapping each other:



- Michael

As to why it sometimes works with MOI's output and sometimes not, it's hard for me to speculate on that since the error is happening inside the pipe bender software.

Have you sent in a file that doesn't work to their tech support to see if it's something they can tune up?

If they require their STEP input to only contain analytic torus and cylinder entities, you'll probably need to use SolidWorks to output that since MOI isn't able to generate that particular type of restricted output right now.

One thing I don't get is why is it using STEP at all instead of taking in the DXF ?

- Michael

Thanks Michael for the investigation - perhaps its just the larger radiuses Ill keep on mental tab on when Moi Fails see if I can pick up the pattern. When it does fail I usually import the same DXF pathway and import that into solidworks - so that all makes sense that there is an underlaying difference on how different surfaces are created. I have tried to contact the Pipebend software developers but they are in China and no reply. With tube bending most parts are 3d so thats why you need to import a 3d STEP file. On this spiral file its 2d but in the pipebend software I overide the rotation on each bend and end up with a 3d spriral. Ill send a picture of that once its bent.

Here is the same machine we use in action to give you a better idea of the process. Some thing like this part in the video I can design that part in MOI in a couple of minutes it really is a killer app for this type of work.

https://www.youtube.com/watch?v=178HPP3v3x4

Hi AlexPolo,

It sounds like the pipe bender CAM is expecting analytic surfaces like toroids and cylinders rather than freeform spline surfaces. I ran into the same problem a few months back when trying to import a STEP generated by sweeping in MoI into a sheetmetal CAM program. You can solve this by using extrude and revolve instead of sweep. Those commands generate clean analytic surfaces. Of course, it's a lot more work.

- Peer

Thanks Peer I tried to simplify the shape as the outer shape can either sqr or round ultimately the machine doesnt know which tool set you put in but still same problem - here is another part created in MOI with essentially the same components a few 90 degree bends - a few straight sections and 1 large arc this file imports into the tube bend software without problems - strange that it work most of the time but with the occasional file its a no go - Ill keep experimenting see if I can pinpoint the issue.