Building the World's First Computer: Babbage's Analytical Engine

My 3D printer (a Lulzbot TAZ 6) is operational again after replacing the controller board because of a bad stepper motor driver.  In the meantime I found a generous machinist with a big CNC mill who is making the framing plates. While I wait for those, I'm printing and stockpiling the assortment of odd-looking pieces that will be needed for version 2 of the prototype assembly. The most complicated of the framing plates is the one to which the 18 stepper motors are attached. Half are for rotational motion and half are for lifting motion. This prototype has one digit wheel stack holding two 4-digit numbers, a set of fixed and movable long pinions that can shift up or down to effect multiplication or division by 10, and one anticipating carriage mechanism that can add or subtract. That will be enough to do simple repetitive calculations, like of the Fibonacci Series. It is not enough to do multiplication or division. I've worked out a scheme to do that, in the next version, with o

 I've been experimenting with new gear parameters using two teeth per digit -- see the previous post -- that should be more tolerant of backlash. The results so far are encouraging. For the prototype driven by stepper motors I'm looking for access to a CNC mill capable of making precisely-located holes in 12" x 18" acrylic plates that are 3/8" thick, and I have two good leads. In the meantime I have made a couple of small manual test jigs using my 8" x 10" Genmitsu CNC router to make the holes in the smaller framing plates for those. long pinion manual testbed anticipating carriage manual testbed Both seem to operate pretty smoothly even though the axle-to-axle spacing is at the spec for the gears, unlike the extra-wide spacing I had to use before that made the backlash worse. In the process of playing with the anticipating carriage mechanism I found and fixed several bugs in my original design: The reset pin on the carry sector lifter could interfere w