admin – Henry York

Pedal Car Frame

Category: Mechanics

| Year: 2025

This is an internal project I did while working at MWW1 Engineering and Prototype Services. Photos are used with permission of MWW1.

I designed and machined components for a prototype of MWW1’s pedal car concept, a hybrid human/electrically-powered micro-mobility vehicle.

I designed the bulkhead in SolidWorks. The bulkhead connects the 5-ft. long aluminum spine of the vehicle with a 2-ft. vertical post. The bulkhead also contains a slot for the motor mount and two threaded holes for mounting idler gears.

Next, I programmed the milling of the bulkhead in FeatureCAM. I then machined the part on the shop’s Haas TM-2P CNC mill. I test-fit the spine and vertical post when machining their interfaces on the bulkhead and then modified and re-ran that section of the program until I reached the desired fit. The bulkhead required five machine setups (orientations in the mill) to complete.

I then designed the motor mount and programmed its machining operations. The motor mount took two machine setups to complete.

After finishing the motor mount, I used a hand drill to put mounting holes in the spine and vertical post. I attached the spine and vertical post to the bulkhead, and then installed the motor mount.

Motor mount before running second setup operations

Spine, vertical post, and motor mount attached to bulkhead.

While completing this project, my machining skills improved in two main areas: optimization and fits.

Optimization was required because a large amount of material needed to be removed from the bulkhead stock in order to minimize its weight. I programmed the mill to use three different endmill lengths for roughing operations, with shorter endmills being used when possible. Shorter endmills chatter less than longer endmills, meaning shorter endmills can be run at a higher feedrate, which minimizes machining time and therefore optimizes the milling program.

Fits were important on this project because the bulkhead interfaces with three components, and a loose fit for any of them could make the pedal car unsafe. Design choices help minimize the risk of a loose fit; two bolts compress the sides of the spine so that it fits tightly with the bulkhead, and three bolts compress the bulkhead so that the vertical post and motor mount fit into it tightly. It was necessary to modify the motor mount in order to make its fit with the bulkhead tighter. I tapped a hole through the motor mount and then added a bolt which presses against the vertical post.

While completing this project, I learned more about designing parts in assemblies, programming and running milling operations, optimizing these milling operations and improving the resulting fits between parts.

Rainforest Model

Category: Art

| Year: 2023

Objectives

Create a realistic model of a rainforest

Process

Cut base from 3mm plywood with jigsaw
Built terrain with spackle
Glued dirt to base, sealed with watered-down glue
Painted dirt and rock with airbrush
Built trees from wire and clay
- Added texture to trunk with resin sand medium
- Painted trunk with airbrush
- Glued leaves cut from cardstock and then painted green
Built smaller plants from cardstock and wire
- Painted with airbrush, then glued to base
Decorated clearing in the middle
- Added static grass in the center
- Made flowers from cut, painted construction paper
Added extra foliage with moss and static grass
Made a monkey from wire and clay, and parrots from cardstock

Conclusions

I am very pleased with how the scenery looks
Using paper to make the plants worked very well

Focus Bracketer

Category: Electronics

| Year: 2023

Objectives

Automate the process of focus bracketing with a digital camera
- Focus bracketing is taking multiple photos of the same subject with different depths of focus
  - These can then be combined in software to create a single photo entirely in focus
- Some cameras have this feature built in, but mine does not
Require no permanent modifications to the camera and be easily removable

Focus Bracketing Example

Single photo; the background is out of focus

Digital combination of five photos taken with the FocusBracketer; the whole photo is in focus

Process

Designed bracket to attach servo motor to camera, and 3D printed it
Created wheel for servo to turn the camera lens
- Rubber grip is a length of audio cable glued to the wheel
Designed PCB in KiCad
- Includes OLED screen and four buttons for the user interface
- Has terminals to connect servo and camera shutter cables
- Controlled by Seeduino XIAO microcontroller, programmed with Arduino framework
  - Chose this board because it can be soldered directly to the PCB, which keeps the device low profile
  - Program allows user to set start point, end point, and number of steps
    - As start/end points are being set, the servo is jogged
Tested device by taking close-up photos of small objects

Reflection

The device generally works well
- Sometimes the servo does not travel to the right place after the endpoint is set
  - This could be because the wheel is slipping
  - Measuring the rotation of the camera lens and providing feedback to the microcontroller could fix this
- Is much more efficient than moving the lens manually, and results in more consistent images
The process was a good test of my PCB milling skills
- This was the largest PCB I had made in a while

Ornaments

Category: Art

| Year: 2023

Santa’s Workshop (2024)

Santa’s Sleigh (2023)

Nativity Scene (2022)

Process

Stable and manger designed in Rhino
CNC toolpath for stable programmed in Fusion 360
Stock for milling cut from 2×6 with jigsaw
Workpiece milled with ⅜ inch end mill at slow feedrate
Stable finished with sanding, wood stain, and varnish
Figures inside stable molded from air-dry clay
- Looks more organic than 3D printed people
Painted with acrylic paint and sealed with varnish
Star in stable milled from brass on CNC machine
- Used very slow feedrate with .8 mm end mill
Finished with filing and polishing

Conclusions

I am pleased with how these ornaments turned out
- I will use clay again in the future as an alternative to 3D printing
I was able to make seven to give as gifts
- Once the first one was done, I was able to make the rest in batches
- This process made the painting of the figures much more efficient

Smart Light Switch

Categories: Electronics, Mechanics

| Year: 2022

Objectives

Integrate fluorescent light fixture into smart home system
Device should work consistently

Process

Tested pulling light chain with servo motor
- Added spring to give the device more pulling force
- Adjusted servo moving distance to pull the chain correctly
Modified lightbulb example from esp-homekit-sdk to control servo
- Runs on ESP-32 development board
Added light state sensor
- Compares two photoresistors to determine on/off state of fluorescent fixture
  - Two photoresistors allow the sensor to be accurate regardless of external light levels
- Interfaced sensor with esp-homekit-sdk to display state of light in smart home app

Conclusions

Successful project- is used daily
Fails to fully pull the chain occasionally
- Sensor allows this error to be noticed by the user so they can try again
- Adjusting servo travel distance may help with this issue, or using a stronger actuator
Chain gets disconnected from servo arm sometimes, but it can be reattached

One photoresistor faces the light, the other away

Bike Eye

Categories: Electronics, In Progress, Programming

| Year: 2022

Objectives

Detect cars behind cyclist and alert them audibly and visually
Provide a cheaper alternative to cycling radars like Garmin Varia™

Process

Tested an ultrasonic rangefinder, but its range was too limited
Decided to use an ESP32 camera board with a machine learning model to detect cars
- Programmed in C++ using ESP-IDF
- Code based off of TensorflowLite image classification and Espressif SD Card examples
- Initial version of firmware only collects photographs and saves to SD card
- Collected about 1100 images to train ML model
Case designed in Onshape, 3D printed in PLA
- Velcro used to attach electronics
- Powered by Li-ion battery

Future work

To complete this project, I will need to:

Add TensorflowLite model to firmware
Create alert system
- Buzzer, if loud enough, or display mounted to handlebars
Expand case
- I think a larger battery will be necessary
Road-test completed device and collect more photos for continued training

Initial ultrasonic rangefinder prototype

Internal electronics attached to case front piece

PCB Probes

Categories: Electronics, Mechanics

| Year: 2022

Objectives

Connect quickly and effectively to PCB traces
Be cheap and easy to make
Allow in-circuit reprogramming of microcontrollers

Process

Tested various designs for probes
- Decided on clothespin because it pushes down on board
Designed PCB tip in KiCad, milled on CNC machine
Designed socket to make swapping probe tips easy, and aligner to keep probe centered
- Socket and aligner 3D printed in PLA
- Socket, aligner and magnets superglued to clothespin
Clothespins magnetically attracted to base, an extra toaster tray
PCB secured to base with double-sided tape

Reflection

Probes were able to program an ATtiny chip in circuit on a PCB- it was a success
If the magnets were stronger, setup would be easier
This project was featured on hackaday.com
- https://hackaday.com/2022/02/27/need-to-probe-circuits-remember-about-clothespins/

RGB Handlebars

Categories: Electronics, Programming

| Year: 2022

Objectives

Make cyclist more visible to cars by adding lights on the sides of the bike
- Makes the shape of the bike more defined than if there were only lights on the front and back
Look cooler than a single color light
Have a long-lasting battery

Process

Initial design used an RGB pattern LED in a long tube
- Tube contains two AAA batteries to provide 3V to the LED
- LED diffuser sticks out from handlebars to be more visible
  - Latched pushbutton underneath turns the light on/off
- Electronics connected with thin magnet wire
Second design was more compact and customizable
- Includes nickel-sized PCB with light circuit
  - PCB milled at home on CNC machine
  - ATTINY 45 microcontroller runs an RGB LED
    - Microcontroller programmed in C++ without Arduino framework
    - Custom light patterns can be added
  - Pushbutton toggles light on/off and changes light pattern
- Powered by two coin cell batteries that together provide ~3V
- Case is 3D printed, with an unscrewable top for accessing the internal circuit

Reflection

The first prototype was very reliable
- Used for almost a year before the diffuser broke off
Second design was more fragile
- If bike is leaned against a wall, the pushbutton is crushed
Both designs are not bright enough to be seen during the day
- Both designs are clearly visible at night
- A higher power LED might be visible in the daytime, but would also draw more power
This project improved my skills significantly
- I got better at milling PCBs by adjusting my workflow and finding better cutting tools
- I created the Clothespin PCB Probes in order to program the PCB, and they have been useful for other projects

UV Curer

Category: Electronics

| Year: 2021

Objectives

Create a timer to control a UV light curing system for resin 3D prints

Process

Circuit designed in KiCad
- A monostable timer design based on a 555 chip
- Timer is connected to a MOSFET to control UV LED strip
Design milled into single-sided copper clad board with an engraving bit
Through-hole and surface mount components soldered
Potentiometer, power supply, and curing enclosure connected
- The potentiometer sets the relative duration of the timer, and the button is pressed to begin the cycle
- When the timer runs out, the lights shut off
- Curing enclosure is a strip of near-UV LEDs inside of a paint can

Reflection

The timer circuit is perfect for my needs – I no longer overcure resin prints
Combining the electronics into a case would make system look cleaner