Erratic Z axis

Hello all,

I've recently followed a guide to put together a 3-axis CNC milling machine, as guided by  this video . In short, the X and Y axes move the gantry using pulleys on a HTD3M timing belt, and the Z axis uses a 5mm pitch lead screw.

I am using 4 TB6600 stepper motor drivers to drive 4 NEMA 23 motors. Going through stepconf, the X and Y axes run fine and smoothly, but the Z axis refuses to work in the same way. It stutters and erratically changes direction.

I've checked all of the connections for the parallel BOB I am using, the driver and motor itself, and I was able to move the Z axis without issue when I started out with the Arduino GRBL kit that was recommended in the video.

Please let me know what I should be looking for. I'm attaching the ini and hal files to this post, and in the meantime I'll re-check all of the wiring.

Thanks in advance for your help!

Well, I apologise - it appears that one of the coil wires was loose! Typical!

After completely removing it and screwing it back into its terminal (while the driver was off), I was able to get a smooth movement out of the Z axis.

Thanks for your time - apologies for not noticing...I've been troubleshooting this thing for days and I may have lost my mind I'm very much looking forward to using LinuxCNC!