Stepper motor locked up

[jeffmorris]

I have 3-Axis ProboStep Stepper Motor Driver Kit with blue stepper motors shown in this link: http://www.probotix.com/3_axis_stepp...tor_driver_kit

I thought that I ruined one of the stepper motors by manually raising Z-Axis too high and I hear grinding noises (I think). Yesterday and today, the stepper motor "locked up" after manually raising Z-Axis too high and I hear grinding noises (I think). Yesterday, I was able to free the stepper motor by turning the knob attached to the unused end of the motor shaft while pressing the "Page Down" key in Mach3 software. Today, I needed vise grip pliers to free the stepper motor. I can't use home/limit switch on the Z-Axis due to the overhead leadscrew on my CNC router. Link for CNC router: http://www.solsylva.com/cnc/cnc_plans_home.shtml

Any suggestions?

[ger21]

Are you sure it's the motor locking up and not the leadscrew binding?

[jeffmorris]

I'm not sure if the motor was locking up or if the leadscrew was binding. I didn't have problems before yesterday. I manually raised Z-Axis too high and I hear grinding noises a few times before yesterday and I didn't have problems before yesterday. I tried to put the home/limit switch on top of the Y-Axis carriage but the bracket that I made from hardboard and a piece of metal angle from VEX robotics kit hits the leadscrew for the X-Axis and I think that the bracket hits the nut securing the tensioning threaded rod on the Z-Axis carriage. There's not enough room between the Y-Axis carriage and the leadscrew for the X-Axis. I want to build a bigger and better CNC router but I have some health problems.

[LeeWay]

What may be happening is you are hearing the steppers missing steps. Sometimes sounds like a grinding noise. This isn't really detrimental to the steppers.
What may be happening is the screw is locking up. Binding on it's own nut and it takes a little torque (more than the stepper can provide) to unlock it or get it back where it should be. Could be the nut or the shaft bearings doing the binding or both.
If there is no way to put a limit on it, I want to see a good picture of it.
There are many ways and different types of switches that can be used.
For a temporary fix, if using mach 3, set up the soft limits at least on the Z. That will help keep you from doing that. Find out which or if the drive train is the culprit and tighten it up too.

[jeffmorris]

I made a new bracket for the Z-Axis home/limit switch by replacing the piece of metal angle from VEX robotics kit with a piece of aluminum angle and cutting about 1/4-inch from the top of the hardboard. Now, there's about 1/4-inch space between the bracket and the leadscrew for X-Axis. I think that there's about 2-1/4 inches of travel on the Z-Axis.