Z軸馬達共用同一個4988驅動器，總讓人不放心，所以marlin有提供解套的方法。
可以在 Configuration_adv.h 裡面找這段
紅色的雙槓刪除後可以用第二個擠出機的4988來驅動第二顆Z軸馬達。
// A single Z stepper driver is usually used to drive 2 stepper motors.
// Uncomment this define to utilize a separate stepper driver for each Z axis motor.
// Only a few motherboards support this, like RAMPS, which have dual extruder support (the 2nd, often unused, extruder driver is used
// to control the 2nd Z axis stepper motor). The pins are currently only defined for a RAMPS motherboards.
// On a RAMPS (or other 5 driver) motherboard, using this feature will limit you to using 1 extruder.
//#define Z_DUAL_STEPPER_DRIVERS
