3D crap

2015-04-24 23.09.21cI got a 3D printer (a PrintrBot Simple Metal model 1403), and it’s been great.  I don’t have time to write much, so I’ll share highlights:

  • I’m on Thingiverse here. I’ve already put up a bunch of crap, including a customizable omni wheel design.
  • I’ve been learning OpenSCAD, a free tool that lets you write code to generate 3D solids.
  • There’s no arc function in OpenSCAD, and the solutions I found online were inefficient or only worked for certain inputs, so I wrote a new one.  See below:
module arc(r,a1,a2,ir=0) {
    // normalize to 0..360 (even for negatives)
    a1n = (a1 % 360 + 360) % 360; 
    a2n = (a2 % 360 + 360) % 360;
    difference() {
        circle(r);
        if (ir != 0) circle(ir); // if inner radius given, subtract it away
            
        // get the a1 to interpolate to, adding a revolution if going the long way
        a1next = a2n>a1n ? a1n + 360 : a1n; 
        
        polygon([
            [0,0],
            [cos(1.00*a2n + 0.00*a1next)*2*r,sin(1.00*a2n + 0.00*a1next)*2*r],
            [cos(0.66*a2n + 0.33*a1next)*2*r,sin(0.66*a2n + 0.33*a1next)*2*r],
            [cos(0.33*a2n + 0.66*a1next)*2*r,sin(0.33*a2n + 0.66*a1next)*2*r],
            [cos(0.00*a2n + 1.00*a1next)*2*r,sin(0.00*a2n + 1.00*a1next)*2*r],
        ]);
    }
}

// test array
for (a = [-360:60:360], b = [-360:60:360]) {
    translate([a,b,0])  linear_extrude(height=10) arc(25,a,b);
}

2015-04-25 15_41_57-arc.scad_ - OpenSCAD

The Pandaphone

2014-12-21 23.10.18I was looking for a gift for my friend’s son, who’s about a year old.  I realized that everything I was looking at was just various enclosures with chips that made sound and light…that’s the kind of crap I can do!

So I built a theremin-type thing. It plays notes based on how close you are to its ‘eyes’, which are an ultrasonic distance sensor, and the nose is a small speaker.

Video:

Build log after the break.

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TerrorBytes Countdown Clock

2014-12-06 12.03.15bThe masses have spoken! After my wildly successful debut as a blog post writer, Tyler and I have collaborated to create a post so exciting that we may just increase our readership to tens of people!

This project started as an idea of Tyler’s. He, my husband, and I all volunteer as mentors for a high school robotics team, the TerrorBytes. The team participates in the FIRST Robotics Competition, which has very strict rules about building times and deadlines. This makes it beneficial to have a countdown clock. Last year, Tyler made one online that we would display at meetings. It was not ideal because it relied on internet and we didn’t have internet that was reliable. Tyler came up with the idea for a physical sign based on an AVR chip and some jumbo 7-segment displays.  The result is the TerrorBytes countdown clock!

Read on for the build log. Continue reading