2015-09-03 (Th) Wrist Mounted Chording Keyboard

Yesterday's recommendations were considered to develop a servo lever which can accommodate the shape of the keypad. Area under the lever was exaggerated to make the first fit easier and allow for measurements to be taken. Model changes were made but another revision may be necessary depending on performance. Corners on the model may need to be rounded (fillet) to keep from catching on clothing, scraping skin or becoming breaking points.

Rotating view of offset servo lever

A single copy of the offset servo lever was printed. Printed components were all assembled to make a makeshift keyboard. No controller had been installed so there was no motion but the levers and servos could be pushed by hand. When the pieces were assembled the offset servo arm fit well and didn't collide with other parts but it had to be placed on four washers so it wouldn't rub on wires connected to the thumb switches. This spacer could be built into the model or the wires could be routed differently.

 Keyboard in the fully deployed position

Keyboard in the transitioning position

When fully deployed, as though ready to type, the parts fit well without a thumbside lever arm which would have crossed the thumbboard if it was straight. Another offset lever arm will be modeled if necessary. When retracted the new offset lever arm had no trouble encompassing the parts but the straight lever attached to the opposite servo collided with the pulleys. Another offset servo arm will be modeled.

Keyboard in the retracted position

Example of where an offset servo arm might go

Servo arm colliding with pulley

Downloadable Files:
To do:
  • Wrist mount
    • Revise offset levers 
      • Shorten offset distance
      • Allow rear bolt hole to bend around
      • Replace far end of lever with servo end
      • Shrink hinge hole radius
      • Make holes in thumb board cylindrical instead of countersunk
      • Model servo arm to go around pulleys
      • Model hinge arm to go around thumbboard
      • Round corners?
    • Integrate:
      • Controller
      • Servos
      • Enclosure for each controller
      • Limit switches
    • Debug
    • Test
    • Refine
    • Repeat
    • Activation switch
    • Route wires
  • Write instructions
    • Make diagram with everything labeled
    • Schematic

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.
Completed projects from year 2

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2015-09-01 (Tu)