{"id":66025,"date":"2019-02-12T19:08:41","date_gmt":"2019-02-13T03:08:41","guid":{"rendered":"https:\/\/www.ponoko.com\/blog\/?p=66025"},"modified":"2019-02-18T11:09:00","modified_gmt":"2019-02-18T19:09:00","slug":"split-flap-display-board-scott-bezek","status":"publish","type":"post","link":"https:\/\/www.ponoko.com\/blog\/maker-success-stories\/split-flap-display-board-scott-bezek\/","title":{"rendered":"Reimagining Split-Flap Boards"},"content":{"rendered":"\n
\"Split-Flap<\/figure><\/div>\n\n\n\n

Scott Bezek Designs A Fresh Take On Classic Display Boards<\/h2>\n\n\n\n

If you\u2019ve ever been to the Amtrak 30th<\/sup> Street Station in Philadelphia, you\u2019ve heard a sound that is found in very few places anymore: The clickety-clack of the split-flap boards<\/a> as they display the latest arrivals and departures. While these relics are mostly memories of a bygone era, artists, makers and engineers are bringing these nostalgic display pieces back to life.<\/p>\n\n\n\n

As the adage goes, \u201cEverything old is new\nagain,\u201d and these unique display boards are popping up all around trendy\nrestaurants and expensive homes. The problem? The price tag. One high-tech\nversion<\/a> that\ndebuted at CES 2018 merges the classic clattering flaps of a retro train board\nwith modern internet technology\u2014and costs upwards of $3,500. That\u2019s a lotta\nscratch to hear the fluttering of shuffling letters.<\/p>\n\n\n\n

Scott Bezek has always loved these\nelectro-mechanical displays, be he wasn\u2019t about to empty his bank account to\nget one. He knew there had to be a better way, and so he set out to learn how\nto make a split-flap board himself.<\/p>\n\n\n\n

Reimagining A Classic Display Board<\/h3>\n\n\n\n

For the next two-and-a-half years, Scott spent much of his spare time researching, designing<\/a> and prototyping<\/a> his version of a split-flap display board. \u201cUltimately, I wanted to design a split-flap display that can be built in small or single quantities, customized and put together for not too much money,\u201d he says. \u201cThis meant using widely available materials and avoiding any tooling with a high up-front cost.\u201d<\/p>\n\n\n\n

To keep it accessible, everything Scott built\nis open source. The 3D model is designed in OpenSCAD, the driver electronics\nboard is designed in KiCad and the driver firmware is written using Arduino. <\/p>\n\n\n\n

\"Split-Flap<\/figure><\/div>\n\n\n\n

\u201cSince this was my first time designing something for laser cutting<\/a>, I started by creating a simple box in OpenSCAD, which differs from other CAD tools in that it uses a programming language to define solid shapes and combine\/subtract\/extrude them into complex designs,\u201d he explains. \u201cAs a software engineer by day, creating 3D models by writing code was really appealing!\u201d<\/p>\n\n\n\n

Each module\u2019s frame is basically a box that uses\ncaptive-nut joints (t-slot joints), which hold a nut in place and allow a bolt\nto hold the perpendicular pieces together. But the most challenging part of the\n3D design was the spool. <\/p>\n\n\n\n

\u201cThe spool is made from eight separate\nlaser-cut pieces and can hold 40 letter\/number flaps (so there are 40 holes\naround the circumference),\u201d Scott says. \u201cThe four center struts provide\nrigidity and prevent the spool from twisting when it\u2019s driven by the gear on\none end.\u201d<\/p>\n\n\n\n

Here\u2019s what the digital models look like:<\/p>\n\n\n\n

\"Split-Flap<\/figure><\/div>\n\n\n\n

Creating these 3D designs in code allowed Scott to easily adjust elements of the design by simply changing the parameters. This kind of parametric design\/modeling may take a bit longer to initially set up, but it is great for iterating prototypes because it\u2019s faster for making changes\u2014saving much time (and aggravation!) in the long run.<\/p>\n\n\n\n

\"Split-Flap<\/figure><\/div>\n\n\n\n

Once the design was finalized, Scott chose MDF for the laser cut parts because this material is affordable, consistent in thickness and softer (than acrylic, for example), making it ideal for pieces that need to slot together. Having some give allows for a nice, tight fit without breaking any tabs when the pieces are slotted together.<\/p>\n\n\n\n

\"Split-Flap<\/figure><\/div>\n\n\n\n

To keep costs low, Scott used store-bought\nthree-inch vinyl stickers to hand-letter the flaps. \u201cIt\u2019s a slow, painstaking\nprocess to cut each letter in half and carefully align and apply them to the\nflaps,\u201d Scott says. \u201cEven after some practice creating my first module, it\nstill took 90 minutes straight to cut and apply the stickers for my second\nmodule.\u201d<\/p>\n\n\n\n

\"Split-Flap<\/figure><\/div>\n\n\n\n

Once the split-flap display module was built,\nit was time to get it moving. Using KiCad, a free open-source tool, Scott was\nable to design the circuit\/schematic and eventually build a custom PCB. <\/p>\n\n\n\n

But one of the most challenging aspects was\nwriting the Arduino code. \u201cThe first trick is getting the motors to spin\nquickly; you can’t just sequence them at full speed from stopped because their\ninertia will cause them to miss steps and just vibrate in place rather than\nturning,\u201d he says. \u201cSo the controller needs to accelerate and decelerate to\nstart\/stop smoothly.\u201d<\/p>\n\n\n\n

The next problem was with the motors\nthemselves. The inexpensive 28BYJ-48 motors Scott used had two variants (not\nlabeled), with one of the variants missing an integer number of steps per\nrevolution. So he had to write the control code in a way to track revolutions\nand keep the spool aligned. <\/p>\n\n\n\n

The final challenge was getting the sensor\nauto-calibration to work. \u201cSince the Arduino controls the angular rotation\nprecisely, it can predict a small range where it expects the IR sensor to\ndetect the home position,\u201d Scott explains. \u201cIf the IR sensor detects the home\nposition earlier or later than predicted, it assumes something went wrong and\nthe module switches into calibration mode. In calibration mode, it rotates\nslowly to find the home position again and resets its frame of reference.\u201d<\/p>\n\n\n\n

Once he worked through all of the engineering\nissues, he was able to perfect the design. Check it out:<\/p>\n\n\n\n