I’m hoping someone can help me diagnose an issue that popped up after some time away from the machine.
I’m cutting a contour through 3/4" MDF using a 201 (1/4") end mill — the same setup I’ve used many times without trouble. However, I haven’t used the machine in a while, and now it’s suddenly losing steps, drifting off the toolpath, or cutting a noticeably wider kerf than the bit diameter. It almost looks like deflection or the machine is getting pushed around.
One thing I noticed: While the machine is powered, it doesn’t seem very hard to push the cutterhead side to side with my hand. There is no slipping of belts or stepper motor shaft (it is turning). That surprised me — Are the stepper motors really this easy to overload?, or is that a sign something is wrong? Is the machine simply losing holding torque for some reason?
Thanks for the quick reply. I checked the following so far.
wiring in good condition and all connectors secure - I’ve unplugged the connectors and checked the pins. There is no burning but this may be an issue if the connection is bad.
belts in good condition and well-tensioned - Yes, already checked.
pulley set screws in place and secure (put a witness mark on the ends of the pulley/motor shaft) - Yes, already checked. The shaft spins when pushing the cutter head.
linear rails/blocks lubricated - These are clean. I haven’t lubed them recently but I think this would be a less likely culprit.
I did some more probing and the wiring seems OK. It’s just the motors are not very strong and can get stalled super easily. It feels very weak to me that I can move the gantry with my hand and not a lot of effort.
The motors are 125 oz./in. — if they don’t hold a commensurate torque, then check the stepper driver wiring and the condition of the chip and the belt tension and condition of the belt?
This would seem to indicate that either the wiring harness connectors are not providing a solid connection, the motor itself is failing or has a poor internal connection, or the driver chip on the control board has started to fail & burn out.
You could try swapping the X-motor wiring harness with maybe the Z-axis (since it’s right there) & see if the issue moves to the Z-axis motor or not - this is to rule out the wiring harness as the issue. Could then try swapping the X & Z motors - if the Z motor functions poorly running off the X-axis driver, then it’s most likely the X-axis motor driver chip that’s not functioning properly.
Also, check your machines’ PSU to see if it’s providing proper voltage while running. The stepper motors need the full 24V to provide their rated torque.