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