Since a few people have asked, let me also add the following note:
For this design, Part #9 (Bosch Pitch Change Gear) is indeed a 55-tooth, 0.7 module gear. This is NOT a typo. They are available from PIC Designs, and can be ordered via
their web site or phone-in orders. Just request part number MSG25-55 when ordering. In our experience, the delivery time for the 55-tooth gear is exactly the same as a more common 56-tooth gear.
The 55-tooth gear was selected as the best-fit solution for the matched free-speed design point we selected for this concept. There is legitimate debate about whether a 55-tooth gear is absolutely needed, or if a more commonly available 56-tooth gear is "good enough." If you like, you can drop in a 56-tooth gear instead. If you do, just adjust the center-to-center distance between the mounting location of the Bosch motor and the first torque shaft (Part 11) accordingly, and you should be good to go.
-dave