Optical encoder bracket for Parallax Arlobot motors

thingiverse

This device holds a US Digital EM1-500 optical encoder sensor in place over a US Digital HUBDISK-2-500 2" optical disk with 5/8" bore mounted to a Parallax Arlobot motor mount and wheel kit (aluminum). It works on both Right and Left motors (just flip it vertically) The original Arlobot encoder wheel is 36 counts per rev, giving 144 counts per rev with quadrature decoding. The EM encoder has 500 counts per rev and 2000 counts per rev as quadrature, giving sub-millimeter accuracy. The Parallax motor does not have a mounting bracket for the EM encoder; that is why I designed this bracket. The 3D printed encoder mount is held in place horizontally between two posts on the motor. The posts can be 37mm +/- 0.5mm apart. The encoder mount has a spring clip that supports variation in the distance between the two posts. The encoder mount is held in place vertically by vertical supports on each end which press between the top and bottom frames of the motor. The encoder holes are 20mm apart and 3mm diameter designed for SAE 4-40 3/4 inch screws. The screw heads are countersunk below the encoder in the 3D printed bracket. The bracket is designed to extend only one end of the motor to avoid interference with a motor mount on one side. On the other side, the bracket has a tab that extends beyond the motor so that the bracket can be removed. There may be other features that interfere and hopefully small filing or modifications can resolve the interference. It takes about 50 minutes to print on my Prusa MK2.