I’ve often encountered the opinion that cnc machining is hard and very unapproachable. Well, currently I don’t share this point of view, even though it had influenced my choices in the past.

What has sparked my interested in cnc?

For a couple of years I’ve worked in the workshop that designed real world models. Which led to questions what is happening with them later on, how are those objects manufactured. Technologies closer to craft and prototyping like resin casting are pretty easy to grasp, but things like injection molding always seemed out of reach. Even more so if you take into account up front costs involved - molds can reach costs in the similar range to ones of a new car. The stories I’ve heard about how tricky the process is discourages many people.

But on my end I’ve kept this subject in the scope of things I’m interested in :) - and luckily I got a chance to try it out.

Broken machine.

One of the local schools had a small cnc mill - it has been unused for a number of years. I’ve asked why, what’s wrong with it - and the only info I’ve been able to get is that from a mechanical standpoint it was ok. Which was encouraging - thus I’ve asked if I can try to launch it. After a while I got a permission from the school management.

It has turned out the machine had been barely used. The only issue was that the electronics were a bit dated. To make things worse the license key for a software that connected to it has been lost. I’ve checked available options and decided to install completely new controller.

Fixes / tweaks.

I’m not a trained specialist when it comes to electronics. My knowledge in the matter has been (and to a degree still is) fairly limited. But the good news was that there was no time limit. Moreover the worst that could happen was that the machine still wouldn’t work. In the best case scenario it would get a 2nd life.

The equipment has been moved to Fablab Warsaw - it was much better space for such operation. I had better access to tools and I had people I could ask for help when I hit the roadblock.

The whole operation had taken around half a year. I’ve installed CSMiO controller from CS-Lab. All the electronics were moved to much more spacious box for which I’ve designed and manufactured proper panel and ventilation.

When it comes to software I’ve again chosen product from CS-Lab, simCNC namely. In the beginning I’ve tried widely popular Mach. It worked, but it’s so clunky and ugly I didn’t want to deal with it. SimCNC fulfilled all the needs, has moderately modern UI, with logically laid out layout that makes it much more straightforward to set up.

First chips. Learning CAM.

So as the machine was operable it was time to put it to test and get some chips flying. When I look back it seems this step was the most confusing part - at least until I’ve actually started doing it. Milling is not at all like for example printing - you don’t actually hit “mill” button when you have your model designed ;) . The way CAD, CAM, postporocessor and control software interact with each other was not clear to me. Articles I found at the time were usually written by pros for pros and didn’t help a complete beginner like me (which makes me think a short article on the matter might be a good idea).

To start off I’ve settled on madCAM (plugin for Rhino) and Fusion360 for CAM work. Both of those have logically laid out CAM interface that does not put too much stuff up front - thus you start with the settings that are the most important ones. My extra praise goes to less known madCAM - it really helped me to understand the steps involved in preparing milling jobs.

For the first projects I’ve used styrodur foam - just to keep things a bit more safe. Consequences of mistakes when milling relatively soft material are fairly low, and is most of the cases you have a chance to hit emergency stop button before things get serious. It quickly turned out that key to milling is good planning. Another important skill to tackle is mounting and securing block of the material you’re going to mill. It was surprising to me how nice results you can get, even on a simple machine, if you get those basics right.

After 2-3 months of testing it was time to return refurbished machine to school.

My own mill.

This experience made me want to keep playing with machining. So I’ve started looking for a small mill for myself that would allow me to continue learning. In the end I’ve picked up a basic machine, quite similar to the one I’ve resurrected.

Again I’ve swapped the controller for CSMiO with simCNC. Even though default controller (Piko) was ok, CS-Lab’s offering seemed easier to expand / tweak. Having a Linux client was extra bonus - I appreciate being able to run the machine on the stable system where I have more control, where I don’t fight with updates. Linux flexible GUI’s also allows me to tweak the interface to suit the machine better.

After a while I’ve added a vacuum table and material probe. The latter was a nice one as it allowed me to learn how to handle those and how to prepare scripts for them.

By the way - I’m super happy I found the probe from the seller linked below. For my needs it was perfect - and very affordable.

https://topcom.cz/

Machining centre job.

Working on my own mill had an unexpected side effect - I got a job as a machining centre operator. Local college needed someone to handle theirs and they were willing to provide some training.

It was really nice opportunity to learn how industrial grade equipment works. I had a chance to train myself in using Heidenhain controller and compare how such professional equipment differs from a hobby or semi pro one.

The experience with tool probe paid off as well - one of the tasks involved getting Renishaw probe into shape.

Final thoughts.

All this led me to simple conclusion - most of the people that can plan a couple steps ahead and have “ok-ish” visual imagination can learn fundamentals of cnc machining.

In a broader sense - instead of getting discouraged by hearing something is difficult it may be beneficial to actually giving it a try. Often actually doing things makes concepts that on paper seem strange / abstract much more approachable and understandable.