Motors and Movement - Printing in Plastic: Build Your Own 3D Printer - page 224

Figure 13-14. Secure the motor mount with the nuts.
Adding the Y-Axis Motor and Motor Mount
Now attach a stepper motor to the Y-Axis Motor Mount (Part R) using four #6-32 x 1-1/2” machine
screws, nuts, and washers as demonstrated in Figure 13-15.