Steppers only move at 0.1mm increments

I just built a Prusa 3 and finally got everything put together, and i'm testing the steppers. They are all moving but once i configured them away from the 78.xxx thats in the default marlin config the only movement increment that i can seem to muster out of the stepper is at a 0.1mm increment.

Any ideas would be greatly appreciated

#EDIT# Its also important to note that larger movements at the default 78.74 step configuration works fine.

Edited 1 time(s). Last edit at 10/26/2014 01:04AM by warnerandy.

What axis are you trying to move?
Z-axis motors with the M5 threaded rod will have a step per mm of 4000
Y-axis with the 20tooth pulley and GT2 belt would be 80 steps per mm
X-axis is the same as the Y-axis if you are using GT2 belt with 20 tooth pulley.

You can see if this is right for you with the Prusa calculator
[prusaprinters.org]

the 'default' steps per mm are not always correct for your situation.

I used the following

// default settings
#define DEFAULT_AXIS_STEPS_PER_UNIT   {80,80,4000,680}  // default steps per unit for prusa i3 rework 680 < 850 < 1060
#define DEFAULT_MAX_FEEDRATE          {500, 500, 2, 25}    // (mm/sec)
#define DEFAULT_MAX_ACCELERATION      {2000,2000,20,1000}    // X, Y, Z, E maximum start speed for accelerated moves. E default values are good for skeinforge 40+, for older versions raise them a lot.

#define DEFAULT_ACCELERATION          2000    // X, Y, Z and E max acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION  2000   // X, Y, Z and E max acceleration in mm/s^2 for retracts

Yes I spent the time calculating the correct steps per mm. The problem is that when I set the config the motors will squeal and or only move part of the requested step. I've tried tuning the pots. I read this morning of somebody suggesting changing the speed of the motor. Would that help?

Thanks.

Try moving slower, like 100 mm/min. 4000 steps/mm is a lot, it requires a lot of processing power.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

Yes, Try with a lower Acceleration rate (2000)
And also have you tuned your stepper drivers?
Turn pots with antistatic tool clockwise until motors make a buzzing noise, then bring back until buzzing is gone and motor is running smooth with good enough torque so your hand cannot stop it.
A lower acceleration may fix the immediate issue, but un tuned drivers are always going to be a problem. As you will have problems with anything bigger than a 20mm cube.