Cineversity

Hi,
I’ve created a model for a client Which comprises several pieces of geometry intended for CNC milling to create repeat moulds. The geometry is quite sculpted, it’s actually a tractor vehicle design for a kids fairground ride, so it has sweeping wheel arches, curved bonnets with fluted detail .. etc. Attached is an example of one of the pieces.

The CNC moulding company have requested .Step files (I had presumed .STL’s would be fine but apparently not) The only solution we found in order to provide a step file was to take the model pieces into vector works and from there export to step but this seems to have doubled up the geometry and the files are unworkable and the CNC company’s end.

Clearly C4D does not have a direct export function to .Step but does anyone know of any plugins or recommended third party software geared for this purpose?

Any help much appreciated.

Thanks

Hi MikeWhiskey,

The “.STL” is not the same as “.STP”.

Cinema 4D has an option to import Step files. The Cinema 4D modeling core is based on segments/polygons; the information is from the start different.

To my understanding, the Step data is mathematically, and when you open it in Cinema 4D, a conversion has to be done to get Polygons.
https://help.maxon.net/c4d/r25/en-us/Default.htm#html/FSTEPIMPORT-CADIMPORT_GRP_TESSELATION.html?TocPath=CAD Import|STEP Import Settings|_____3

Tessellation is the keyword here.

Cinema 4D has no option to translate that process back. Like going from a Polygon based Sphere to a description (simplified) “Sphere, 100” instead of defining all vertices (points) and the points that create a polygon.

The round trip Cinema 4D to Vectorworks and then Step-export that you describe above leads to turning every Polygon into an object. This causes a massive increase in file size.

You can open Step files in a text app to see the difference.

Was the model done in Cinema 4D or with a CAD application?

All the best

Thanks for your reply Dr.Sassi. Very much appreciated.

Yes the source model was created in Cinema 4D. Modelled in symmetry using sub division surface and generally pulling the geometry around, adding loops etc until we were happy. Then baking that down to OBJ.
For the record, I’m a bit of a novice to this way of modelling, but the outcome seemed pretty good and clean keeping the loops to an efficient minimum while retaining good curved forms around the body work. That model was then used by my client to make a 3D printed maquette for for approval from the end client and that was very successful from the OBJ. The problem was then getting the files exported as Step for full scale CNC milling.

For the CNC step files we broke the vehicle down into its constituent parts (bonnet, Wheel arches, doors…etc) and exported them as separate files.

Thanks for the tip regarding the ‘round trip’ through vectorworks. That was clearly the case. An item that started as OBJ at say 12MB was trippling (or more) in size by the time it passed through vectorworks and ended as a .Step.

We’ve ended up having to try reducing the geometry as much as possible by taking loops out where we can but we don’t want to compromise the final design aesthetic in something that was already very efficient and end up with a model that starts to look faceted. We’re waitng to hear back as to whether these files worked at the CNC end.

But I suppose the up-shot is that Cinema 4D is not best placed for exporting to Step. We were told after completing the model that Step and Iges files are the only formats that this company can work with. Hence wondering if there’s any good, trusted conversion software out there for exactly this purpose.

I’ll keep looking and hopefully the last files I sent for CNC work.. Fingers crossed!

Thanks

Thanks for the background story, MikeWhiskey.

Cinema 4D is not able to export Step at all. The Data you create in Cinema 4D is an entirely different set of information than a CAD would produce. You can go from Step to Polygons. To my knowledge, there is no tool in Cinema 4D or VectorWorks that allows going from Polygons to Step. (Thinking about full geometry definition and not taking a polygon-based object apart, which would perhaps not be seen as a model at all, as they are independent “segments” by then.

This can’t be converted back to my knowledge, at least not with tools I had the pleasure to work with.

What you need to do, is to make clear to the Company with the CNC that you have polygon-based information and that a suitable STL file or DXF can be provided.

Good luck.