Support for distinct E factors

Marlin/example_configurations/RigidBot/Configuration.h

@@ -148,6 +148,9 @@
 // :[1, 2, 3, 4]
 #define EXTRUDERS 1  // Single extruder. Set to 2 for dual extruders
 
+// Enable if your E steppers or extruder gear ratios are not identical
+//#define DISTINCT_E_FACTORS
+
 // For Cyclops or any "multi-extruder" that shares a single nozzle.
 //#define SINGLENOZZLE
 
@@ -469,27 +472,33 @@
  *
  * These settings can be reset by M502
  *
+ * You can set distinct factors for each E stepper, if needed.
+ * If fewer factors are given, the last will apply to the rest.
+ *
  * Note that if EEPROM is enabled, saved values will override these.
  */
 
 /**
  * Default Axis Steps Per Unit (steps/mm)
  * Override with M92
+ *                                      X, Y, Z, E0 [, E1[, E2[, E3]]]
  */
-#define DEFAULT_AXIS_STEPS_PER_UNIT   { 44.3090, 22.1545, 1600, 53.5 }  // default steps per unit for RigidBot with standard hardware
-                                                                        // default steps for 16-tooth pulleys { 100.06, 50.06, 1600, 76 }, HPX2-MAX E=504, RigidBot E=53.5, Peter Stoneham's=76
+ // default steps per unit for RigidBot with standard hardware
+#define DEFAULT_AXIS_STEPS_PER_UNIT   { 44.3090, 22.1545, 1600, 53.5 }
+// default steps for 16-tooth pulleys { 100.06, 50.06, 1600, 76 } // HPX2-MAX E=504, RigidBot E=53.5, Peter Stoneham's=76
 
 /**
  * Default Max Feed Rate (mm/s)
  * Override with M203
+ *                                      X, Y, Z, E0 [, E1[, E2[, E3]]]
  */
 #define DEFAULT_MAX_FEEDRATE          { 500, 500, 5, 25 }
 
 /**
  * Default Max Acceleration (change/s) change = mm/s
+ * (Maximum start speed for accelerated moves)
  * Override with M201
- *
- * Maximum start speed for accelerated moves: { X, Y, Z, E }
+ *                                      X, Y, Z, E0 [, E1[, E2[, E3]]]
  */
 #define DEFAULT_MAX_ACCELERATION      { 800, 800, 100, 10000 }