Mini-Project - Edge-Lit Acrylic National Champions Sign

/Engineering

Overview

 

Before I made the WallPaw with the WS2812B LED strips and edge-lit acrylic, I wanted to make a smaller prototype project.  We had recently won the 2016 football national championship, so it seemed like an obvious choice.  

The box has a pushbutton and a on/off switch on the side.  The pushbutton is designed to change the lighting mode, but I haven't updated the code to support that function yet.  Currently the sign just does the scrolling rainbow effect.

The batteries last a pretty long time, but we only turn it on for 20 minutes or so at a time.  

Some things I learned:

  • When you laser etch acrylic, it needs to be cast acrylic.  The acrylic you buy at Lowes/Home Depot in sheets is extruded acrylic, which doesn't etch correctly.  Cast acrylic has a nice uniform frosted look when etched, extruded either doesn't etch at all or doesn't look uniform.  This sign was made using extruded acrylic, which is why it isn't as bright on the top as on the bottom.  

  • Measure twice, cut once.  The box I cut out was wide enough for the battery box, but I forgot to measure the Arduino Uno before I made it.  As a result, the Uno is tilted sideways in the box so that it would fit.  

    • Don't trust online laser-cut box generators.  The one I used didn't make a box that would actually fit together.  It should've been obvious when visualizing it, but it definitely didn't work.  I had to cut off some wooden tabs and just glue the box together. ​

  • Glue doesn't like to stick to acrylic.  I ignored this and just used more hot glue until the lights stayed, but you could peel them off easily.  ​

  • Stain your wood before you put things together.  The stain makes it look a lot better, and is easier to apply when the wood can be laid flat on a table.  

Features and Function

  • On/off toggle switch
  • Removable side piece for easy battery replacement
  • Push-button to change lighting mode
  • Cordless (battery powered) 
 

Parts list

 
Parts
  • 1/4" thick wood

  • 1/4" acrylic sheet

  • WS2812 LED strip - 1 foot

  • Arduino Uno

  • 4 AA batteries and battery holder

  • Toggle switch

  • Push-button

  • Connector wire 

  • DC barrel jack connectors

  • Wood glue

Tools
  • Laser cutter

  • Soldering iron

  • Hot glue gun (this is essential)

  • Wire cutters/strippers

Design

 

My main goal when designing this was to easily be able to swap out the rechargeable batteries.  I decided to leave one wood panel easy to remove, and do the hard wiring on the other side.  The on/off switch is glued on the right side, with fairly short wires running between it and the Arduino Uno.  The wooden panel on the right is also glued in tightly.  

I used hot glue to attach the LED strip to the acrylic piece - it barely worked, but with enough hot glue it stayed.  

If I made this again I would use extruded acrylic so that the etching is nice and frosted instead of clear-ish like this piece.  I would also use screws instead of glue, so that I could easily access the Arduino to reprogram it.  

Jacob Thompson

jat5@clemson.edu

Clemson, SC

© 2020 By Jacob Thompson

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