This is a general question. Not long ago I was asked to make a 3d model for an iron casting and the foundry asked for a step file which I made in Rhino and the casting was a success. I have also made stl files for 3d printing. I know that the foundry had someone make wooden molds for the casting using a CNC machine of some sort. I now have a desktop cnc router and have used it to make a simple rabbit shape in wood and have used it to make isolation cuts to make a pc board. I’m still very much a newbie in cnc but I’ve learned a lot about G codes and am using a program called Estlcam for general things and LineGrinder for pc boards. Estlcam doesn’t seem to recognize .step files but does .stl files. I have a .step file that I want to make and I can import it into Rhino and it looks good. Can I directly convert it, or export to an .stl file? What’s the ‘best’ way? I can try it and see what happens, but I thought I might tap into better ways by asking the question.
You can make an STL from a STEP file, you can export it from Rhino.
Most CAM programs work with NURBS formats like STEP and IGES only, not STLs…
There reason why STEP or other NURBS format is preferred is that the CAM software can generate an optimized tool path by considering multiple factors. On the other hand, STL resolution is fixed, therefore toolpath generation is significantly limited.
@Joe4 You can create a mold from either a NURBS model or a mesh model, and you can even use both in the same mold. Look here.
Thanks @cdordoni for the explanation of why the step file is preferred. Thanks @brvdln for the link to the discussion. I’ve got a lot to learn. Unfortunately, I don’t get to do as much of this sort of thing as I’d like, but I keep learning. Every one I do, I try to get better. Thanks @JimCarruthers , I did export the step file I had been given to stl and was able to play with it in my CAM software.
For example, a couple of years ago I used the trial version of RhinoCAM. I created a surface with a pattern, then split it into two parts: I left one half as a NURBS surface and converted the other half into a mesh. I ran a basic toolpath simulation, and it worked fine because the tool continued machining seamlessly when moving from the NURBS surface to the mesh without any issues.
I tried a few different CAM softwares before taking to Estlcam. I somehow missed knowing about RhinoCam but I doubt I would have tried it because of the cost. Maybe someday if I can justify having more than a hobbyist CNC router, I’ll change my mind. At the moment I am having some “fun” learning the ins and outs of tools and tool paths.
Keep in mind that I’ve only tested it briefly. Unfortunately, the company I work for has been using Cimatron since it was founded, so switching to Rhinocam is practically impossible. The senior designers are used to that software and continue to work with it. I don’t have major complaints about the CAM side of it, but I find the modeling tools very outdated and limited compared to modern alternatives.
In fact, as the CAD modeler, I rarely use Cimatron except for some mold-related work. The two designers who handle mold design and machining at my company still use Cimatron for their daily work. If it were up to me, I would switch to Rhinocam without hesitation.