Had 17% humidity in the shop and while cutting I went over to the computer, which is on a metal storage cabinet next to the table and had a static discharge. It seems that discharge caused a loss of communication to the acorn controller and required me to restart cnc12. I also noticed on the table all of the bolt heads holding down the dust covers had some cool sawdust structures formed from static electricity. I would have expected the table to be grounded through the connection and hanging of the controller boxes but it appears if it is it is not good enough to dissipate the static buildup. Any thoughts on how I should protect myself from static build up and causing the controller to go offline when I have a static discharge? Should I change to a heavier shielded network cable?. Directly ground both the computer cabinet and table? Any thoughts are appreciated. Luckily this time was on a short cuts and I just rest things and ran it again.
Its always good to use a sheilded Ethernet cable between your computer and CNC controller. The two systems are often isolated from each other (laptops often don’t use grounded power supplies), and the CNC environment, especially with the dust collector can really build up a charge. Static discharges are one of the main causes of gliches when running a Gcode file.
Second, a floating metal (i.e. insulated from earth ground) cabinet is also bad. That has a lot of surface area to store charge on, and because its metal it can conduct all of that charge out rapidly when you touch it, or jump to your computer or network table once the voltage gets high enough. If you feel a good shock when you touch it, you are already at 20kVolts or more.
You can tie the cabinet to your shop’s electrical ground (NOT nuetral, only the earth ground), or to a grounding rod (you can drill a small hole through your concrete and drive a small rod into the earth and wire the cabinet to the rod. Or you could just run a wire from your cnc chassis to the cabinet. Lots of ways, and it doesn’t have to be a super low resistance connection to dissipate the charge buildup, any little wire will do.
I’ve experienced a similar issue. I have a shielded cable but my dust collector seemed to be in too close proximity to the Avid control panel. I moved it further away and that seemed to address the issue.
All of our ethernet cabling for EX is shielded. Sounds like you need to ground that cabinet and your machine frame to earth. As Jim said that should keep your static buildup from happening.
Try it out with some jumper cables to see if it helps. If it does come up with a more permanent solution.
Probably something else worth noting is that even if you don’t have issues where you are seeing erratic behavior, you should try to set up your dust collector hoses to self-dissipate (buy the dissipative hose for the last section that connects to your dust boot and ground it), and make sure non of your cables (motor, sensor, ethernet, everything) come in close proximity to the dust hose or boot (a few inches away is good).
The discharge from a DC hose can be massive compared to what integrated circuits are designed to safely handle. A spark you can see and hurts can easily destroy any chip on the electronic boards if it finds its way in.
Another thing to look out for is when you clean off the top of your spoilboard with a shop vac. Those can build up a ton of charge if its dry, and its easy to come in contact with wiring and damage something that way. A couple years ago I blew out the input that handles the touch plate and had to replace the board.
The Acorn has pretty good voltage clamps and opto isolators, but they all have their limits. Even the servos have a controller in them so they could be damaged as well.