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Open Source Truing Stand (in progress):

Problem: I'd like to get into wheel building, especially for more unique wheels which can't be purchased preassembled (IGH, dynamo hubs). However, most truing stands are very expensive, especially those which use a caliper-style truing system (which I prefer) over simple adjustable screws on the left/right sides. The Park Tool stands can cost well over $500.

Goal: Low-cost bicycle wheel truing stand that can accommodate a variety of wheel sizes and hub widths. All parts manufacturable with simple tools (no mill/lathe)

Design: Aluminum extrusion was chosen to build the frame due to its straightness and ease of use. Extrusion allows for easy mounting of accessories like a disc brake rotor alignment gauge or tool holders. Steel plates increase the rigidity of the frame, The truing stand sits on a stable H frame base with rubber feet.

The arm pivots to accommodate different size wheels (20-29"). The arm pivots freely until locked in position by a clamping screw. This was chosen over a knob-adjustable system due to the lack of datasheets and availability of appropriate torsion screws. The caliper is almost entirely 3D-printed and rotates about two press-fit bearings. The calipers are curved outwards to provide clearance while truing wheels with the tire on and accommodates up to 3" tires. The caliper is adjusted via a knob, which pushes against the two caliper jaws and spreads them apart, opposing a rubber band closing them.

The truing stand accommodates varying-width hubs by using different 3D-printed top caps on the vertical pillars of the stand. Using replaceable top caps greatly reduces the cost and potential play introduced by a pivoting or linear motion system. The stand is fitted with caps for all hub widths (100, 120, 126, 130 and 135mm) and axle sizes (9mm quick release, 10mm nutted) of bikes I own. The fact that they are printed allows for easy expansion to accommodate boost hubs and through axles.

Design Document:

Bike Wheel Truing Stand

BOM:

Bike Wheel Truing Stand BOM

SolidWorks rendering

GoKart Steering Wheel (Dec 2024 - July 2025):

Goal: Comfortable, low-cost steering wheel for the Electrium Mobility GoKart, while providing readily accessible controls to a driver wearing racing gloves.

Design: The main frame of the steering wheel was decided to be a simple aluminum plate, coupled to the steering shaft by an angled steel coupler. Both of these are simple to manufacture, and the large flat plate provides ample mounting space for buttons and displays.

The grips were custom sized to fit the driver's hands, with the contour and placement of buttons done per hand measurements. The grips flare out at the top to secure the thumb. The contours were modeled using SolidWorks surface modelling.

The team has had some experience in manufacturing polyurethane skateboard wheels, so the same leftover material (Smooth-Cast 60D) was used for the grips. However, the team has previously cast it in silicone molds, which has been quite expensive at $80/bottle (Smooth-On EcoFlex). Instead, I pioneered a novel 3D-printed mold method. This consisted of designing a PLA mold with alignment pins, vent hole, and a seam along the side to inject a hot glue seal. These molds were then sanded smooth, coated in filler primer, sanded again, and then clear coated. They were then covered in Smooth-on Universal Mold Release.

The mold was clamped on to the aluminum plate and the edges sealed with hot glue. Polyurethane resin (with black mica powder mixed in for color) was then injected with a 150mL syringe. This was left to cure and then the mold released easily from the grips. No damage was done to the molds, allowing for their immediate reuse for the grip on the other side.

In order to provide speed and battery data, an I2C OLED screen and a Seeed XIAO ESP32S3 were used. The OLED provides a crisp display of the simple values, and the Seeed ESP32 is one of the most compact MCUs available. An MCU onboard the steering wheel was necessary due to previous experiences with interference when transmitting I2C over long distances. The ESP32 communicates with the primary vehicle ESP over CANBUS using an SN65HVD230 CANBUS transceiver through a braided repurposed ethernet cable with all connections wired in redundant pairs. All of these are soldered to a hand-wired perfboard, which was a first to me. The ESP32 is socketed for easy replicability, and the cable is doubly-secured with zip ties for strain relief.

The steering wheel has several inputs for the driver to use. These include two compact thumb buttons for quick actions like radio toggle. As well, there are two paddle shifters to allow for display interfacing. These are printed in PETG-CF for added durability. They have magnets embedded using epoxy to allow for a tactile, snappy actuation. When pressed, they actuate microswitches.

Electronics are housed in simple screw-on PLA enclosures with embedded heat set inserts for serviceability. The screen is covered in acrylic to provide protection to the fragile display. All periphral devices are connected to the perfboard with JST-SM connectors for easy replacement.

Results:

38% reduction in grip casting costs using 3D printed molds compared to silicone molds. 3D printed molds are much more durable and can be reused 5+ times.
Highly ergonomic grip shape and button placement.
Clear and effective display with simple, tactile controls.
Easy serviceability with quick swap components.

Next Steps:

Neodymium magnets in the paddle shifters are currently held in place by only epoxy and easily pull out of position when the epoxy fails. Redesign paddles to insert magnets from the back of parts.
Paddle shifter microswitches are not able to be serviced as they are secured using epoxy to the lower paddle shifter housing. Redesign to be screw-in.
Paddle shifter paddles are not stiff enough. Redesign thicker/with reinforcing ribs.
Weatherproofed electronics. Electronics are not protected currently.

The finished steering wheel

Steering wheel backside. Note the paddle shifters.

3D-printed molds. Note alignment bulges, injection port, and vent hole.

Hand-wired perfboard

Mounted to the perfboard is the ESP32 and CANBUS Transceiver

Raspberry Pi Point-and-Shoot Camera (in progress):

Goal: Configurable point-and-shoot style camera based around the Pi Camera HQ. Simple interface (shutter only) with options for more adjustment if deemed necessary.

Design: The design relies on a Raspberry Pi Camera HQ module, Pi Zero 2W, and Adafruit PiTFT Plus 2.8" Capacitive touch screen. The Pi Camera HQ was chosen due to its high image quality and support for interchangable lenses. The Pi Zero 2W was chosen because it is the fastest Pi in the Zero form factor, which is beneficial for the live preview. The PiTFT was chosen due to the good image quality, compact form factor, and because it opens the possibility for a touchscreen UI.

The system is powered by a pair of 18650 cells connected to a charging board, totaling to 5000mAh. This provides excellent battery life for multi-day trips. The system also has a secondary low-power MCU (ATtiny85) for power button monitoring. This allows for greatly extended battery life, as the Pi Zero 2W alone draws 600mW at idle (which would drain the battery in ~30hrs), while the ATtiny85 draws about 1/1000th of the power. The ATtiny85 monitors the state of the power button and safely shuts down the Pi, cuts power via a G700P06J MOSFET, and then waits for another button press to turn the Pi back on.

The system is housed inside a 3D printed, leather wrapped case with ergonomic handle. The design provides sufficient room for future expansion (gyroscope for horizon levelling, RTC for timestamping, etc.).

eBakfiets Electric Cargo Bike (Jan - Aug 2024):

Goal: Electric Dutch "bakfiets"-style cargo bike with custom frame, electronics, and control interface.

Design: Custom AISI 4130 chromoly bike frame developed in SolidWorks Weldments. The frame features an adjustable tie-rod steering system, large plywood cargo box, disc brake mounts, support for a suspension fork, and heavy-duty center mounted kickstand.

The rear triangle was fully welded on a universal, adjustable aluminum extrusion welding jig, while the entire frame was assembled by tack welding the tubes in place on a low-cost, disposable MDF welding jig with a cost of $70.

The bakfiets was powered by a 48V, 12S 3P battery pack using 21700 Molicell P28A cells. This battery pack was housed in a waterproof 3D-printed case which could be qucikly removed by sliding off rails mounted to the cargo box. Using a FlipSky VESC and custom-designed antispark module, this powered a 26" 1200W geared hub motor.

It featured a centrally-mounted ESP32, which controlled the relay for the front/tailights, as well as a WS2813 addressable RGB strip underneath the cargo box which allowed for underglow lighting effects and turn signals. This was connected to a handlebar mounted ESP32, which allowed for an OLED battery/speed display and turn signal/lighting controls. These were all connected to a custom-designed power distribution board, which adapted the 48V battery power down to the 12V and 3.3V needed for the lights and MCUs.

Results:

Independently designed frame, welding jig, and working steering system.
Highest power battery and motor system the team has operated to date.

Next Steps:

Improved welding jig with cutouts to permit access from both sides, as well as additional stiffening and reinforcements.
Further funding to continue work on final integration, additional parts, and PCB production.

Remote-Control Airplane (Aug 2020 - Sept 2021):

Goal: Low-cost fixed wing RC airplane to learn the fundamentals of aircraft controls and electronics.

Design: Foam frame, removable wing for easy transport, and easily replaceable plywood motor mount in case of crashes.

Servo-driven rod-actuated elevators and rudder.

Results:

Learned soldering and basic electronics theory.
Completed entire project for under $100, undercutting consumer RC airplanes.
Easily serviceable and replaceable airframe.

Next Steps:

Landing gear to avoid dangerous hand-launching.
Fine tuning of control surfaces and remote control system to reduce control sensitivity.

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