Motors only move one direction, endstop configuration problem?

firmware: Marlin 1.1
Control: Pronterface 2015.3.10
bed: 305mm x 305mm
controller: miniRambo

Replacing a broken Rambo with a miniRame

Please see next message.

Edited 1 time(s). Last edit at 11/24/2016 08:13PM by charlieRC.

Ok, problem has changed.

I managed to get the X and Y axis's to work correctly, but I still have an issue with the z axis. It moves up and down in the correct direction, but since the origin has not been set, it stops pretty high above the bed. If I hit the Z home, the motors make an awful screeching noise and move very slowely downward. The screeching is so loud that I hit the reset button on the miniRambo right away.

Question is: Why would the Z motors seem to work perfectly if I click 10mm up or 10mm down, but then when Z home is clicked, they screech very loudly and move very slowly?

You may have the Z-Homing-Speed set too high. Or you may have the Z-Acceleration set too high. Also check the MAX_FEEDRATE numbers (for Z). Probably something is set high enough the motors can't do what they are being told to do.

Holly cow!!! That was it.

The line in configuration.h was...

#define HOMING_FEEDRATE {50*60, 50*60, 4*60}

I changed that last parameter to 4*30 and the problem seems to be solved. Would 120 work as well as 4*30??

I've been fighting with this all day. Man, I wish I could buy you a cup of coffee (or what ever your preference is) but I can only say Thank you!!!
still have an issue with that endstop, but I'm pretty sure I will figure that out easy enough.

Quote
charlieRC
Would 120 work as well as 4*30??

Yes! The 60 is there to make the units more clear. The feedrate number needs to be in mm per minute. But mm per second is more clear to the user.

To be clean, you could have changed the 4*60 to 2*60. But the important thing is you cant be all the way up at 240 steps per minute.