SubSum Mechanical Calculator

Description

Having seen Steven Freeborn's video on the Adall calculator, I was inspired to make my own. The SubSum is the result.

Usage Instructions

• Reading
  First look at the number at the right of the slot In the bridge, that is your tens and digits. Then look at the last number the centre of the ball passed, that is your hundreds. Note care must be taken not to confuse 99 and 199.
• Addition
  Zero the SubSum. Locate your first number in the outer ring of numbers on the housing, insert the stylus into the closest notch in the spinner, rotate clockwise until stopped by the bridge. Check the result on the bridge. Repeat for the next number.
• Subraction
  Set the bridge to display the number you wish to subtract from. Locate your first number in the inner ring of numbers on the housing, insert the stylus into the closest notch in the spinner, rotate counterclockwise until stopped by the bridge. Check the result on the bridge. Repeat for the next number. Note the SubSum cannot display display negative numbers.

Parts

One 5mm ball is needed.

This has been designed around a 0.4mm nozzle and a 0.2mm layer height. Smaller may work but I have not tested them.

Assembly

1. Clip the spinner onto the housing's central peg
2. Place bearing in track
3. Slot end of bridge onto outer housing peg
4. Align ball with slot in bridge
5. Clip bridge onto the housings central peg