Hi,

i am using ramps 1.4 with A4988 drivers. I am not using any jumpers for micro-stepping. I am also building the Kossel mini printer.

When i command the g28 command on PrinterFace to my printer, the stepper motors hum but do not go to their home positions. The motors have a lot of torque however they do not move. The endstops are all working correctly and i checked each driver and stepper motor individually and they all work. The wires are all connected correctly. When the power if off and i move the stepper motors they all make the Arduino light up. does anyone know that the problem is?

thanks!

If you're not using microstepping you will probably want to turn down all the acceleration values in the firmware, and get the drivers providing the right amount of torque. The standard acceleration values in Marlin are fairly aggressive for even for many normal printers at 16x microstepping.

Note: If you don't use microsteps, then expect each "step" to be fairly large, and that your machine will produce fairly inaccurate results at small scales. Many printers are designed to give somewhere around 0.1-0.2mm accuracy with 16x microstepping (depending on the mechanics of the printer, such as if it's made with metric or imperial threaded rod, the type and pitch of belts, etc).