Trouble with random "lines"

I’ve been running a few pocketing jobs the last few days without any problems. Today, I noticed two random lines in the work piece, which worry me. I’m using ramps 1.6 (Marlin 2.0.0) with the full graphic LCD controller. I also noticed some problems with the display of the lcd (duplicate files with the same name, files dissappear from the screen, …weird stuff). I checked the cabling and it looks ok. I tried pulling the SD card out during a machine run, and it stopped. So that rules that out.

The jobs take around 4 hours each. The machine is placed in a garage with an ambient temperature of 5C. The temperature of the heatsinks, located on the DR8825 drivers, is between 16 and 30C. The measured voltage, between the pots and ground is between 0.68 and 0.69V for all three drivers. I use these motors.

These random lines appear in both directions (x and y), while I haven’t (yet) noticed an issue with the z. The picture I posted only shows lines in the x direction.

LIYCY PRO 4X0,5mm2 signal cable is used for the wiring, which I joined (at the end) with ordinary dupont (breadboard) cables to connect to the ramps board. I don’t use a router, but a 500w chinese spindle, which is commonly used with the mpcnc.

To rule out the gcode generating application, I ran the same job twice. It ran fine once, but these issues occurred the second time.

Would anybody know, what could be the cause of this?

Update: I discovered, that if I turn the spindle speed, on the controller, to the max (and Marlin is not fully booted yet) right after powering both boards (spindle controller and ramps), the issues with the lcd display (sd card files not shown, duplicate) are back. If I wait that marlin first boots and then I turn the spindle to the max, the files are listed correctly. Perhaps these two issues (random lines and lcd display issues) could be related. Here is a video showing the issues.

Some of those spindles are extremely electrically noisy. Shielding all of there wires, and shielding the LCD’s cables should help/fix it.

Thank you, Ryan. What I was surprised about was, that the machine ran fine for about two weeks. These issues only started to occur yesterday. Do you know why that happens? Does the spindle “degrade” in some way so it generates more electrical noise?

Not really sure, it if is brushed, perhaps they are wearing down in an odd way and sparking more? Or maybe your wires are just a little closer than they used to be.