Build Instructions

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• 1

  Supplies

  1. 2 x Single-axis joystick modules
  2. 1 x Custom ESP32-S3 based hand controller
  3. 1 x ESP32-S3 DevKitC board
  4. 1 x Flipsky 75100 dual ESC running VESC firmware
  5. 2 x Flipsky 7070 BLDC motors
  6. 1 x Hailong Li-Ion Battery Pack (36VDC Li-Ion battery pack, 10S3P configuration)
  7. 1 x Generic furniture dolly from Home Depot
  8. 1 x Step2 platic poolside chair (different colors available)
  9. 1 x Adhesive-backed solderless breadboard
  10. 1 x Set of JST-ZH cables + connectors to connect to the Flipsky 75100 dual ESC
  11. 1 x Assortment of multi-color heat shrink
  12. 1 x Assorted jumper wires
  13. 2 x Micro-USB to USB-A cables
  14. 2 x XT-90 to XT-60 adapter
  15. 2 x XT-60 extension cable
  16. 1 x Set of adhesive wire clips
  17. 1 x Set of 4 x rubber furniture dolly wheels (2 x rigid, 2 x swivel)
  18. 1 x Roll of black PLA+ 3D printing filament
  19. 1 x Wrench set
  20. 1 x Staple remover tool
  21. 1 x Stapler tool with staples
  22. 1 x Thread-checking tool set
  23. 1 x Automotive brake pad spreader tool (to force the dolly caster wheel brackets apart and make more room for the chain drive mount components)
  24. 2 x Tritan 55VX32 flat sprocket, one for each rear caster wheel
  25. 2 x Uxcell #25 chain roller sprocket with 10mm bore, 25-tooth (lower torque, higher RPM)
  26. 2 x Uxcell #25 chain roller sprocket with 10mm bore, 10-tooth (higher torque, slower RPM)
  27. 1 x Wen drill press to drill out the Tritan 55VX32 sprockets
  28. 1 x Set of metric drill bits for the Tritan 55VX32 sprockets (and useful in general)
  29. 1 x Set of 82-degree countersink drill bits for the flat head screws that mount the Tritan 55VX32 sprockets
  30. 1 x Chain breaker tool
  31. 2 x #25 chain master links
  32. 1 x Length of #25 chain
  33. 1 x Cordless drill
  34. 1 x Set of motor phase wire banana bullet connectors
  35. (Optional) 1 x Pair of 3-pin motor phase wire connectors to prevent accidental reversed wiring
  36. 1 x ZH-1.5mm connectors kit
  37. 1 x 3.2 foot length of LED strip lights (144 LEDs per meter, cut to equal lengths for each side of the dolly)
  38. 1 x Logic level converter breakout board (for sending commands from the ESP32-S3 dev module [3.3V logic] to the LED light strips [5V logic])
  39. (Optional) 1 x High-current battery on/off switch
  40. 1 x Soldering + hot air reflow station (for soldering cables)
  41. 1 x Spool of solder (for soldering cables)
  42. 4 x 1/4"-20 bolts (for mounting the folding seat on the dolly)
  43. 1 x Set of flat-head M3 machine screws (for the electronics enclosure top, and mounting the sprocket to its adapter on the wheel)
  44. 1 x Set of M3 heat set threaded inserts (for the electronics enclosure base)
  45. 1 x Set of #6 x 5/8" flat head Phillips wood screws (to mount the sprocket adapter to the caster wheel, and the 3D-printed electronics enclosure + battery mount to the underside of the dolly)
  46. 1 x Assortment of M4 flat head machine screws (to attach the Flipsky controller to the electronics enclosure base)
  47. 1 x Assortment of M3 pan head self-tapping wood screws (for the custom PCB controller + enclosure assembly)
  48. 8 x No. 6 x 5/8" pan-head wood screws (to attach the motor mounts to the dolly)
  49. 16 x 1/4"-20 Nylon lock nuts
  50. 16 x 1/4"-20 x 2 inch long carriage bolts (if spares are needed for mounting the new caster wheels)
  51. 2 x 3/8"-16 female threaded knobs (for the rear-wheel studded knobs)
  52. 2 x 3/8"-16 x 3 inch long threaded studs (for the rear-wheel studded knobs)
  53. 2 x 3/8"-16 Nylon lock nuts (for the rear-wheel studded knobs)
  54. 1 x Tube of thread locker
  55. (Optional - for racing flags) 1 x Pair of 1/2" to 3/4", and 3/4" to 1" EMT-conduit telescoping couplings
  56. (Optional - for racing flags) 1 x 6-foot piece of 1/2" EMT conduit
  57. (Optional - for racing flags) 1 x 6-foot piece of 3/4" EMT conduit
  58. (Optional - for racing flags) 1 x 6-foot piece of 1" EMT conduit
  59. (Optional - for racing flags) 2 x Flag clips
  60. (Optional - for racing flags)1 x Checkered flag
  61. (Optional - for racing flags) 1 x Orange safety flag
  62. (Optional - for racing flags) 2 x Flagpole ground stakes
• 2

  Mechanical Assembly

  I 3D-printed (PLA+ filament) the Flipsky BLDC motor mounts, and the enclosure for the Flipsky dual ESC motor controller and peripheral/receiving ESP32-S3 dev board. I added 4 x M3 heat-set threaded inserts to the base of the 3D-printed enclosure so that the lid could be attached with M3 screws. For all printed parts, it is best to print with 100% infill to help reduce the chance of breakage. Using a tougher printed material like Nylon over PLA would further strengthen the build.

  The furniture dolly originally came with 4 x swivel caster wheels. I opted for rear wheel drive for this build, and first removed the swivel wheels on the rear of the dolly and replaced them with fixed (i.e. non-swivel) wheels. I used this set of 2 x rigid/fixed, and 2 x brake/swivel wheels which are made from a soft rubber, which makes for a much smoother and quieter ride than the stock plastic wheels that came with the original furniture dolly.

  To install the new wheels, first remove the carpet/coverings on the front and rear of the dolly. The dolly was assembled by first bolting together its wooden planks using carriage bolts, and then covering them with carpeting material + staples. This staple remover tool can be used to tease out the staples. Then, the carriage bolts can be removed. Drill new holes to match the landing pattern for the wheels, re-attach them with the same bolts, and cover the newly-drilled area with carpet and fresh staples to re-hide the drill holes and bolts. Drill out the holes for mounting the plastic chair which is mounted on top of the dolly (the chair can be removed when you want to transport furniture instead of people.) This plastic chair turned out to be exactly the right size for this project, is foldable for dolly storage, has a carrying handle on its rear, and has multiple color options.

  The new pair of fixed rear wheels may have slop/play in the inner bearing in the center of each wheel. To help reduce lateral slippage, use a hammer to repeatedly tap the flared head of the inner bearing of the wheel, to reduce the gap between it and the inner race of the bearings.

  I used a wrench set to remove the lock nuts and carriage bolts from the original wheels on the dolly, and drilled mounting holes for the new wheels. Each wheel bracket has 4 x slots in its metal base which help with adjustability. I measured the thread size of the original carriage bolts (1/4"-20 x 2 inches long) using this tool set, and with the thread size determined, I used these nylon lock nuts to attach the new wheel brackets to the furniture dolly. After installing the new wheels, I re-added the carpet to the dolly using this stapler tool to maintain that "furniture dolly" look and feel.

  I wanted to be able to fold the dolly when not in use, and I needed a cheap and lightweight seat for the assembly. I found this poolside plastic seat which has a folding backrest, and even has a lip on its front end to fill the gap between the rear and middle planks of the wood on the dolly. I bolted this seat to the dolly wood using these 1/4-20 screws and 1/4"-20 Nylon lock nuts.

  To make installation, removal and replacement of the rear caster wheels easier, I built two studded hand knobs using female threaded knobs and 3/8"-16 x 3 inch long threaded studs, bonding the two together using thread locker.

  Note: Keep in mind that for all parts which may be subject to vibration, it is best practice to use nylon luck nuts where possible, and thread locker where appropriate, so that the fasteners don't shake loose over time.

  The Chain Drive and Motor Assembly section of this article provides details on how I modified the dolly to include the chain drive system.

• 3

  3D-Printed Parts

  All 3D-printed parts were made using PLA+ black filament. These printable part files are all available at this Thingiverse link. I recommend printing with 100% infill to help reduce the risk of part breakage. The files include:

  1. Flipsky 7070 BLDC motor mount
  2. Flipsky 75100 dual ESC module enclosure bottom + cover
  3. Hailong Li-Ion battery bank mount (uses zip ties)
  4. Adapter to mount the sprocket to the rear caster wheels
  5. Sprocket holder to make modifying it easier
  6. 2 x Custom joystick caps (i.e. throttle/left, and steering/right)
  7. 10mm spacer and 5mm spacer for the 3/8"-16 studded knobs for the rear caster wheels

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