Francis Qin

Projects For Recruiters Resume

Projects

Things I've designed, printed, wired up, and debugged.

Servo-powered robotic arm

May – Aug 2026

SolidWorksRaspberry Pi Pico 2Servos3D Printing

A four-joint desktop arm (base, shoulder, elbow, and gripper), each joint driven by its own hobby servo. I designed and iterated the parts in SolidWorks, printed the full assembly on a Bambu Lab printer, and checked fit, range of motion, and structural integrity before final assembly. Two thumb joysticks on a breadboard steer it, and a Raspberry Pi Pico 2 reads them and drives the servos.

An orange and green 3D-printed robotic arm on a desk, with a servo mounted on its round base, a parallel linkage up the arm, and a two-finger gripper reaching down — The printed arm. The shoulder servo sits on the side of the base, and the parallel linkage keeps the gripper level as the arm reaches.

A breadboard with a Raspberry Pi Pico 2 and two thumb joysticks, with jumper wires running out to the servo leads — The controller: a Pico 2 and two joysticks on a breadboard, wired out to the four servo leads (labelled with tape).

how it's wired

control signalpowerground

Simplified signal flow, not a pin-for-pin schematic. Servos can pull a lot of current when they start moving or stall, so they run off their own 5 V supply rather than the Pico. The supply's ground is tied to the Pico's ground so the PWM signals share a reference.

how it works

Each joystick axis is a potentiometer, so pushing the stick changes a voltage that the Pico reads with its analog-to-digital converter.
The Pico turns those readings into a target angle for each joint.
A hobby servo sets its angle from the width of a pulse repeated about 50 times a second, roughly 1 ms at one end of its travel and 2 ms at the other. The Pico generates a separate PWM signal for each of the four servos.
I calibrated each servo's endpoints and the motion sequencing through repeated test runs, so the joints move to the same place every time and stay inside the range the printed parts allow.

what went into it

Several design revisions in SolidWorks, refining part geometry and the assembly between prints.
Printing the whole arm on a Bambu Lab printer and test-fitting before final assembly to check range of motion and structural integrity.
Writing down each iteration and test result to guide the next round of mechanical and control changes.

Tabletop board game

Oct – Dec 2025

SolidWorksAutoCADLaser Cutting3D Printing

A fully functional tabletop game built for two clients by a three-person team. I led it from start to finish. The board is two mirrored halves, one per player, laser cut from MDF with finger-jointed walls. Each half is split into scoring zones worth +1 to +5, with a goal pocket at the far end. The pucks, blockers, posts, and goal arch are all 3D printed.

Two laser-cut MDF trays side by side, each marked with scoring zones from +1 to +5, with white 3D-printed pucks and angled blockers, a rubber band stretched between printed posts, and a white printed arch over a goal opening — The final prototype: two mirrored halves, laser-cut MDF with 3D-printed pieces.

how the board is laid out

laser-cut MDF3D printedrubber band

One half of the board from above, simplified. Piece positions vary from game to game.

how we built it

Produced the complete CAD package (part models, assemblies, and manufacturing drawings) in SolidWorks and AutoCAD.
Ran prototyping cycles with 3D printing and laser cutting, reworking geometry and assembly around playtesting feedback and the places parts failed.
Ran our design reviews, documenting decisions, test outcomes, and revisions until we landed on a prototype the clients approved.