NEMA17 Sub-Micro Servo Bracket for Auto Bed Leveling

thingiverse

This bracket is designed for a NEMA17 motor to accommodate a sub-micro servo, such as the Hitec HS-55. If you're using a direct drive extruder (http://www.thingiverse.com/thing:147705), there's ample room underneath for the servo. The servo mount aligns the output shaft with the hotend, behind it. It works well with Marlin's Auto Bed Leveling feature. The microswitch used is a Philmore 30-2505 sub-miniature switch with a roller, but any similar switch of that shape should fit. The switch's roller end is positioned just under the servo's axis. To assemble, print the parts in ABS for heat resistance, using 0.2mm layer heights, 2 perimeters, and 40-50% fill. Use a Hitec M23-I double-ended servo horn or its single-ended counterpart, M23-L. Insert the servo horn into the arm's recess, bond the cover plate with acetone or glue, and secure it with a zip-tie. Attach the microswitch underneath the center line of the arm, secure with another zip-tie, and attach the servo arm to the servo using a servo screw. For the bracket assembly, insert M3 nuts into the recesses, short M3 screws into the retaining bar's holes, place the servo in its designated spot, secure it with servo mounting screws, and slide the bracket under the stepper motor. Make sure it's snug and doesn't move. In Marlin firmware settings, define NUM_SERVOS as 1, SERVO_ENDSTOPS with corresponding servo indices for X, Y, Z (or disable with -1), SERVO_ENDSTOP_ANGLES for X, Y, Z axis extend and retract angles, X_PROBE_OFFSET_FROM_EXTRUDER, Y_PROBE_OFFSET_FROM_EXTRUDER, and Z_PROBE_OFFSET_FROM_EXTRUDER.