This blog is actually about a small disaster I have with my home made CNC. And I named it "Electronics - Part 2" because I believed that the problem seems to be with the electronics.
So I have GRBL controller on the CNC and everything works fine. The next thing I would do is to machine the end piece again for my Y-axis extension. This time I planned to machine it in aluminum. So I got some 5/16" aluminum, and go really slow with it (0.2mm per pass). It took a long time and I was watching the process, and got really bored. So I closed the enclosure and went on to do something else. When I got back to it after a while, I heard that something is wrong. I rushed in, and went for my panic button.
It was bad. The machine goes to some completely weird path. The end mill bits are broken. Not only the work piece is ruined, it gouged a deep mark onto my compound table. In additional, all the alignment of the machine is all thrown off.
I have been thinking about what went wrong. Eventually I came to a conclusion that this might be an isolation problem with the electronics. The step stick stepper motor driver I am using have both the logic and the driving power supply connected. The noise from the driving power side might get into the processer side and messed with the serial commands. That's just a guess based on logic deduction, and I have no prove for it. That give me an immediate next step work item, that is to build an isolation stage into my controlling electronics.
This really highlights another important aspect of working with machines and tools - the safety is a very important issue that can not be stressed enough. It was fortunate that I have an enclosure for the CNC, so whatever went wrong stays inside the cage. It is also a great practice to have a panic button that can stop all the machine operations right away. Because when you are at that moment, there is not much logic deduction going on. A pre-defined single safety action (such as pushing one button) would be a great feature to have for any machine.
For now, I will stay with machining plastic materials and stay watching it all the time during the process.