Sure thing @Dick , here’s why I recommend using FIND HOME regularly. If you have a background in CNC machining, I apologize for “over explaining” certain aspects of the system. My hope is that future users can reference this answer if they have a similar question.
The Short Answer
FIND HOME moves a motor in the zero direction until it hits an impassible object (usually the end of the rail). Once it hits this hard object, it sets that position as point zero. Since the end of the rail is unlikely to move it makes a good reference point for the device to calculate movement off of.
The Long Answer
FarmBot Genesis uses stepper motors to move in each direction. Unlike traditional motors, stepper motors operate in “steps” (as the name would imply). This means that the FarmBot software can send a single pulse to the motor to move it a known distance.
Although FarmBot’s software can track the number of pulses that it sends to the motor, it can’t be 100% sure that each pulse resulted in a real-world movement. For example, there might be tension on the belts that slows the motor down, or the gantry might have been blown backward by a strong wind.
Because of this problem, FarmBot uses “rotary encoders”, which attach to the axis of each motor and measure the actual number of steps the motor has moved, not just a pulse count. FarmBot can compare the number of pulses sent against the number of actual axis movements to determine stall conditions or to apply error correction to movement problems.
Now imagine that you have a device that performs an OS update. The device goes offline and while it is offline, let’s suppose the wind moves the gantry 100mm. During this time, FarmBot will “loose track” of where it was and all movement will be incorrect by at least 100mm.
For this reason, I like to always do a FIND HOME before doing any serious operations- it’s just a good way to be 100% certain that FarmBot’s idea of “0” matches real-world conditions. That’s not to say that FarmBot loses track of its position often, rather I feel that the extra effort of adding a FIND HOME step gives me extra certainty about my device’s movement accuracy.
I hope this gives you a better understanding of how FIND HOME works!