Enlarged board to add a 4thAxis that can clone the X,Y or Z axis. With a 4th option to use pin D12-13 tocontrol it. Added a breakout header for allthe Axis’s Added a communication headerfor UART(Serail) and I2C Added the a connector for anoptional fuse.(Fuse not supplies as it needs to be selected for the currentthat will be used.) Capacitors are mountedhorizontally giving more clearance between them and the stepper drivers. Goodfor ventilation. Added a pull-up resistor on theaxis enable pins. This prevents the pin from being in a floating state Added2 mounting holes