Packaging
The gantry needed useful planar travel while fitting inside a product with significant space constraints.
MIT 2.009 · Product Engineering Processes
Scribbly
A team-developed embroidery accessory that turns a user-provided image into thin, washable guide lines on fabric. My primary responsibility was the compact XY gantry and its mechanical integration.
Mechanical DesignCADGantry SystemsPrototypingTesting
01 · Overview
Turning a product concept into a working motion system
The gantry had to fit within the product envelope while moving a range of fabric and hoop sizes accurately and reliably.
Scribbly converts digital designs into washable guides drawn directly onto fabric so users can embroider the pattern afterward.
My primary responsibility was the gantry system: mechanical architecture, CAD, motion-stage mounts, moving components, assembly, alignment, and testing. The broader team developed the enclosure, product form, garment interface, electronics, and other product subsystems.
02 · Design
Compact motion without unnecessary complexity
Packaging, reliability, and precision had to be balanced within a constrained consumer-product envelope.
Reliability
The mechanism deliberately used fewer belts and fewer opportunities for failure, treating simplicity as a performance requirement.
Precision
Motor speed, torque, available power, payload, stiffness, and positioning precision had to be considered together.
Mechanical architecture
A lightweight H-belt gantry built around linear rods
The motion system used NEMA 17 stepper motors, four 0.25-inch linear rods, oil-impregnated bushings, and spring-loaded belt clips for tension.
Motion architecture
Two rods ran front-to-back and two left-to-right. The rod diameter balanced low moving mass with sufficient stiffness for the target motion.
System integration
The gantry geometry and mounting had to coordinate with the broader team's enclosure and product packaging while preserving usable motion.
03 · Build
Details that made the mechanism buildable and tunable
Assembly features were designed around practical alignment, tensioning, guidance, and constraint rather than assuming perfect manufactured geometry.
Alignment
The gantry was squared with a dial indicator before being bolted to the stationary frame.
Belt tension
Spring-loaded belt clips provided tension without bulky dedicated tensioners.
Guidance
Linear rods and plain bushings created a compact guidance system with low part count and straightforward assembly.
Constraint strategy
The mechanism was designed to avoid overconstraint, reducing binding and improving tolerance of manufacturing and assembly variation.
04 · Test & Iterate
Design, build, measure, and refine
The gantry moved from requirements and architecture through detailed CAD, assembly, dial-indicator alignment, and full-product testing.
1
Define
Translate product needs into travel, payload, speed, torque, power, and precision requirements.
2
Design
Arrange motors, belts, rods, bushings, and moving stages within the available package.
3
Align
Assemble, tension belts, square the motion system with a dial indicator, and secure it to the frame.
4
Integrate
Test the gantry inside the full product and verify usable motion.
05 · Result
A functioning gantry integrated into the final product
The completed motion system provided approximately 10 inches of travel and about 0.5 mm positioning resolution while carrying a lightweight payload of roughly 5 ounces.
The final product successfully turned digital artwork into physical guide patterns on fabric.
For the gantry, the central challenge was balancing mechanical design, packaging, motor sizing, manufacturing, alignment, reliability, and system integration.
06 · Gallery
From concept development to the final machine
These images show the broader team's product development as well as the gantry and final drawing results.
