Re: mirror prints

Reversing could be X or Y axis reversed


Identify your type of machine
Identify where your end stops are

On I3 the Bed moves in Y, Y is backwards from what you think. (remember movement is relative to the extruder)
On I3 type machines Min end stops are at Left, Back and Down positions, if they are elsewhere they are maximum end stops

Find in configuration.h the section on endstop directions eg

// ENDSTOP SETTINGS:
// Sets direction of endstops when homing; 1=MAX, -1=MIN
// :[-1,1]
#define X_HOME_DIR -1
#define Y_HOME_DIR -1
#define Z_HOME_DIR -1

Adjust to match your endstops positions. (NB with ramps you may need to move the endstops plugs, min and max endstops uses different pins)

Now check your direction of moment,
X -ve should move head left, X+ve should move head right
Y -ve should move bed back, Y +ve should move bed forward
Z -ve should move head down, Z +ve should move head up

Either invert these in firmware or in hardware as needed.