Array size
12 x 12
Problem
What the build needed to solve
My contribution
Pin CAD, guide-feature design, clamp-interface iteration, FDM prototype fabrication, laser-cut housing integration, and mechanical testing.
The system needed to convert climbing-route image data into a physical tactile map. The main mechanical challenge was not strength; it was repeatable pin motion. The pins had to rise smoothly, avoid binding in the guide plate, lock in the raised position, and remain readable by touch inside a compact tabletop prototype.
Constraints
Design boundaries
Convert route-image data into a raised tactile pin pattern.
Package the mechanism into a compact tabletop demonstrator.
Use a 12 x 12 pin array with FDM-printed PLA pins.
Reduce binding between pins and guide holes.
Keep the pins readable by touch without sharp contact.
Work within the limited output of an SG90 micro servo at 5 V, approximately 3 N at a 2 in arm.
Build log
Design evolution
The mechanism was developed through physical iteration. Each revision was printed, assembled, tested, and changed based on pin-rise behavior, binding, tactile readability, and housing fit.
Revision
Failure mode
Design change
Result
Early pin array
Pins were too tall, heavy, and prone to guide-hole binding
Reduced pin height and section size
Lower actuation effort
Solid pin geometry
Too much lift force for SG90 servo
Added partially hollow PLA geometry
Reduced pin mass while keeping return behavior
Early guide/clamp
Pins tilted or failed to lock
Iterated guide features and side-holder geometry
Improved raised-position stability
Tactile interface
Pin tops were less readable and less comfortable
Rounded tactile top
Improved touch readability
Final demonstrator
Needed integrated route display
Combined laser-cut housing, pin grid, actuator path, and electronics
Smooth locking across tested route patterns
Details
Technical details
System function
Physical tactile map for climbing-route information
Array configuration
12 x 12 tactile pin array
Pin material
FDM-printed PLA
Pin geometry
Partially hollow body, rounded tactile top, flared/flat base
Measured pin body length
~6.91 cm
Exposed tactile travel
~1 in
Actuator constraint
SG90 micro servo at 5 V, ~3 N at ~2 in arm
Housing
Laser-cut birch plywood
Prototype generations
4
Route images tested
14
Actuated pins per route
~20-40
Early failure mode
~60% pin-rise failure from binding and geometry issues
Final result
Smooth locking across tested route patterns
Funding
$2,000 NYU Prototyping Fund
Testing
Results
Prototype generations
4
Route images tested
14
Pins per route
~20-40
Early pin-rise failure
~60%
Final result
Smooth locking
Pin length
6.91 cm
Material
PLA
Award
$2,000
The prototype was tested through functional route-image trials rather than formal durability cycling. Across 14 climbing-route images, each route actuated approximately 20-40 pin positions. Early designs showed roughly 60% pin-rise failure due to guide-hole binding and pin geometry issues. After revising pin mass, guide behavior, holder geometry, and base contact shape, the final tested patterns achieved smooth locking across the tested routes.
The engineering evidence for this project is physical iteration: printed prototypes, guide-fit testing, route-image functional testing, housing integration, and observed reduction in pin-rise failure.
Scope note: This was functional prototype testing, not a fixed-cycle durability qualification.
Reflection
Engineering lessons
- The primary failure mode was friction and guide-hole binding, not pin fracture.
- The strongest improvement came from changing the pin, guide, and clamp geometry together rather than treating them as separate parts.
- Future testing should include a 100-200 cycle actuation test, measured jam count, guide-clearance study, and direct force measurement with a scale or force gauge.
Gallery
CAD, fabrication, and test views
CAD
Custom PLA pin geometry with rounded tactile top and reduced-mass body
CAD
Hollowed pin profile used to reduce servo lift load
CAD
Laser-cut flat-panel housing with dense pin grid
Final
Integrated demonstrator with pin array, actuation hardware, and electronics