6,400 mechanical, color-changing spools of thread.


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The F21 Thread Screen, built for Forever 21, is a 2,000 pound machine that can dynamically display images and basic animations with 6,400 mechanical spools of thread. By driving a custom belt made of fabric, each spool can display one of 36 colors, thus making up a larger image at an 80x80 resolution. At launch, the Thread Screen is showing Instagrams that have been tagged with #f21threadscreen.

A Feat of Engineering

Over a year and a half in the making, the F21 Thread Screen is one of the most complex machines ever built for a brand. It's comprised of over 200,000 parts - over 8 times what you'd find in your car. Every component, from the thousands of motors and gears, to the 600 pounds of milled aluminum, to the turned wooden spools - all have been custom designed, engineered, and manufactured from scratch. Despite the massive complexities living under the hood, the result is a beautiful and simple looking display that is mesmerizing to watch.

How it Works

Each spool has a 5 1/2 foot long piece of threaded fabric that rolls over top of it, similar to a conveyor belt. The fabric is made up of 36 colors, each 1 3/4 inches in length. Instagrams that are hashtagged with #F21ThreadScreen are automatically captured and optimized for the screen’s 80x80 resolution, then each spool’s motor drives the fabric to it’s appropriate color. Each ribbon also features a reflective strip which is scanned by an infrared sensor, which tells the machine the color each spool is currently showing, allowing for corrections for any slip that may occur.

Some Stats

• 200,000 total parts - 8 times what goes into a modern car
• 6.7 miles of threaded fabric - enough to cross the Brooklyn Bridge 6 times
• 6,400 spools - stacked on top of each other, they’d be taller than the London Eye
• 2,000 lb / 900 kg

Animated GIF Tests

Hardware Highlights

  • Aluminum Super Structure.
  • 32 channel stepper motor driver PCBs with optical homing sensors.
  • Each fabric belt features a small retroreflective strip for homing on the optical sensor.
  • 6,400 bipolar stepper motors.
  • Injection molded ABS module chassis with wooden spools.
  • Drivetrain uses brass and acetal gears and silicone coated molded acetal driveshafts.
  • Each stepper motor  is limited to around 180 - 200mA @ 12V, which gives a maximum peak of 1,280 Amps at 12 Volt, or 15kW.

Software Highlights

The web server pulls images from Instagram for certain hashtags, queuing them up and sending to our render server software which calculates best visual representation for the image based on available colors on the fabric. We then send out commands to the motor controllers over 10 RS485 buses (20 modules per bus) and a picture or animation appears.

  • Ruby
  • Node.js
  • Firmware written in C and C++ 
  • Bash
  • Linux 
  • WebGL 
  • FFmpeg
  • SQL