Converting a STEP file to G-code for CNC milling 3D surfaces

I thought this was going to be just a one-click export or something like that but unfortunately not, since G-code apparently requires drill bit specifications embedded in the file… so that’s why CNC operators can charge so much money… :stuck_out_tongue_closed_eyes:

But searching this forum most people seem to mostly mill “2D” stuff… and the best bet for generating output for 3D I’ve found so far is this:

Anyone else have any experience with actually milling 3D surfaces and preparing your own files and if so, what did you use that didn’t cost an arm and a leg?

I have something which needs to be milled from both sides (but I have mounts for threaded inserts so it can be screwed into place when turned), but maybe that disqualifies it from me ever producing my own files and expecting someone else to be able to mill and line it up?

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G-code depends so much on machine and tools used so unless you have your own machine, you need a really good reason to dive into this.

I did some tool path simulation to evaluate different cutters for 3 axis milled longboard wheel wells but it was only a simulation.


That’s not even the beginning of it. Machining is an entirely separate vocation from design, regardless of any magic CNC genie, and you’re mostly likely to destroy your machine, or get yourself physically injured. And if you want to get into CNC machining, for crying out loud buy the proper CAM software actual machinists actually use, farting around with some stupid free DIY solution, especially as a non-expert machinist, is preposterous, it’s the definition of knowing just enough to really get yourself into trouble.


It’s a bit disheartening to want to dive into a new hobby like this one and find that the same old company dominates even here… :face_with_diagonal_mouth:

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Not quite sure what you mean…Autodesk? No, Fusion does not dominate CAM. Specialists in the CAM field dominate CAM. Go to an injection molding shop and they’ll be using stuff you haven’t even heard of.

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A good application for getting your head around the CNC process is DeskProto. Their evaluation is unique in that is let’s you actually save GCode for a while where most just let you look at it.

Jim is spot on. If you’re seriousl about getting into CNC, trying to learn on your own is expensive and dangerous. You’ll be breaking $100+ tools and potentially launching shattered tool steel across the shop at subsonic speeds. Go take a machining course at a local Community College with good hand’s on experience, overseen by someone that knows the ins and outs and will keep you from accidentially perforating yourself or a classmate.

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If you look around Grasshopper-land, you may find some tool-path generators. There was one that did 5-axis, that perhaps be dumbed down to 3, err 2.5D.

Mew? GitHub - fellesverkstedet/Bark-beetle-parametric-toolpaths: A grasshopper plugin for digital fabrication. Enables direct fabrication of geometry with 3D printers, CNC milling, Laser cutters, Robot arms and more. Also featuring 1:1 augmented reality toolpath projections.

I’ve used LinuxCNC for running my machine, and I was looking into PyCam, though their development stopped, which is a shame. Because it’s just Python, it would seem that something like PyCam could be implemented in Rhino, perhaps without threatening the makers of many fine tool packages, well not really for the last part.

FreeCad also has some CNC ability. It imports Rhino Step files just fine. It’s very left-brain and tedious to draw in, for a Rhino person.

Nudge: I wish there was an entry-level CAM solution for Rhino3D - #10 by Brenda

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IKR. I get so frustrated when most ppl think 2.5D is 3D! :rofl:

So far Mecsoft and CNC Software, and cost me an arm and a leg :sob:

I have machines and tools, and I want to antiquate the CAM/CNC industries.

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That’s more of a ‘disclaimer’ than anything – imo.

I’ve been doing CAD/CAM/CNC for over 18yrs, and I’m so tired of so many things associated with ‘proper’ this and ‘proper’ that – to say the least.

I’m literally a master machinist, so we’re good there.

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I’ve heard of all of it pretty much, and it’s all pretty well dominated by one hand-full of corporate entities that all of them are feeding off of and private labeling from.

Hmmm another ‘disclaimer’ lol.

DeskProto interesting though – heard of them plenty. But did another quick looksee. Noticed they’re owned by Delft Spline Systems and not seeing any association with the proverbial MW/MW :thinking:
which is good, unless I’m missing something.

Also, I’m familiar with their ‘Roland’ ideology/tech, even though I’m not really a believer in that approach – while I do know lots of people are.