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Imported from GitHub: KilowattSynthesis/Braille-Display-CAD · commit 9ad9629 · license CERN-OHL-P-2.0

Description

Experimental design for a braille display using build123d CAD in Python

README

Braille-Display-CAD

Experimental design for a braille display using build123d CAD in Python

Interesting Parts

Explored Ideas

Pogo Spools

  • Laser printer fuser-like roller mask.
    • Branch: archive/pogo-spools
    • Files: ideas_pogo_spool_mask/
  • Made PCB with small stepper motors, tiny CAD parts (spools).

RF Inductors as Electromagnets

  • Use Mouser's "RF Inductors" selection, mounting an inductor vertically.

    • Branches: archive/inductor-smd-vertical, archive/inductor-smd-flat
    • Eaton makes good-looking ones. 3225 metric (1210 imp) is too big; 2520 metric (1008 imp) might be okay. 2012 metric (0805 imp) is great!
    • "Power Inductors - Leaded" are never small enough.
    • Filter to >= 20uH inductance. Filter to >=70 mA.
    • Examples (Vertical-Mount):
      • BWLD00241715 -> Not stocked in smaller quantities, though.
        • 2.4 mm x 1.72 mm x 1.52 mm
      • LBR2012T470M -> 0805 imp (2012 metric). 47uH. 75mA rated max.
    • Examples (Horizontal-Mount):
      • VLS201612CX-220M-1 -> 22uF, very good, but shielded.

  • Test results:

    • 4mm x 4mm x 3mm 33uH coil-wound SMD power inductor (ASPI-4030S-330M-T) can point a magnet. Magnets stick to the inductor always though.
    • Several inductors, up to 6mm diameter (and 1-2 MH), with 24V get very hot, but don't levitate a 1mm or 2mm neodymium magnet.
      • Good at pointing pointing the magnet, if it starts far away.
      • Cannot remove the magnet from the inductor once it's stuck.

  • Conclusion: RF inductors don't have enough magnetic force to levitate 1mm or 2mm neodymium magnets.

Nut/Bolt Grid

  • Turn a bolt in a threaded hole/nut. Each bolt is a dot. User directly touches the dot.
  • Movement can be done with one motor per dot (very tiny motors, maybe stacked), or motors can be moved between dots (CNC plotter style). Multiple heads can be used.
  • Branch: archive/cnc-plotter
  • Files: cad/nut_bolt_grid.py, cad/vertical_motor_layers.py

Silicone Sheet

  • Use CNC plotter to manipulate a silicone sheet which can pop up and down.
    • Branch: archive/silicone-sheet
    • Files: cad/silicone_sheet_mold/

Unexplored/Unrealized Ideas

  • Investigate bi-metallic strip with actuator.

  • Investigate shape memory alloy (SMA) approach. Benefit: Would be very quiet.

  • Should buy some 4mm solenoids.

  • Key and lock mechanism pushes up on the pins

  • Use GT2 belt (or similar) to press up on pins.

    • T2.5 belt is probably best - https://www.aliexpress.com/item/1005004668423141.html
    • Could try to TPU 3D print belt with the perfect braille pattern, in a closed loop. Teeth on the inside, and pattern on the outside.
    • Spring pushing on pogo pin flange, on solenoid-relieved cell frame.

  • Use CNC plotter to turn pins/bolts for placement. Use hex drive, plus solenoid to mate/un-mate. Build the plotter on a PCB with 3mm linear rails, belts, etc.

    • Branch: cnc-plotter
    • Bolt options - Search "M2.5 plunger"
    • Best option: M1.6 Grub Screw, probably.
    • Create top plate with Z-stacked nuts on it.
    • Screw driver or nut will move up and down and turn screws.
    • Search "Micro Linear Motor" for gantry.
    • Focus on M1.6 and M2.5 designs.
    • To move the screw:
      • Use a spring to push the bit up, and a solenoid to pull it down.
      • Use a hex bit maybe, or use rubber friction.
    • BOM:

  • Motors mounted on orthogonal PCBs, with rotating slanted plate to push on the pins.

    • Use magnets as the mating, somehow.

  • Microfluidics as valves.

  • MEMS on-chip stepper motor:

  • Double screw with balls and weird geometry.

  • Cams on 2.4mm diameter rods that run along each column of dots.

    • Each cam would have 8 positions, so 45 degrees per position.
    • Would probably need to move table up-and-down independently of the cams.
    • One motor per cam, probably.
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