How to write binary STL

I'm trying to write binary stl's from Processing, I've done ASCII stl's before but they get way to big. I'm using the wikipedia article on binary stl to write them, but I can't get it to work.

Here's my code:

try {
    for (int i=0; i!=80; ++i) {
      binfile.write(b[i]);      //useless header, as long as it doesn't begin with "solid"
    }

    binfile.write(0);
    binfile.write(0);
    binfile.write(0);
    binfile.write(4); //needs to be a 32 bit number, so yeah...
    for (int i=0; i<s.getVertexCount(); i+=3) {
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);
      binfile.write(0);//normal vector, doesn't matter
      for (int j=0; j!=3; ++j) {
        float x = s.getVertex(i+j).x;
        float y = s.getVertex(i+j).y;
        float z = s.getVertex(i+j).z;

        int convertX = Float.floatToIntBits(x);
        int convertY = Float.floatToIntBits(y);
        int convertZ = Float.floatToIntBits(z);

        binfile.write(convertX >> 24);
        binfile.write(convertX >> 16);
        binfile.write(convertX >> 8);
        binfile.write(convertX);
        binfile.write(convertY >> 24);
        binfile.write(convertY >> 16);
        binfile.write(convertY >> 8);
        binfile.write(convertY);
        binfile.write(convertZ >> 24);
        binfile.write(convertZ >> 16);
        binfile.write(convertZ >> 8);
        binfile.write(convertZ);
      }
      binfile.write(0);
      binfile.write(0);  //attribute byte count (16 bit), never used
    }
    binfile.flush();
    binfile.close();
  }
  catch(IOException e) {
    println("Oh no! ");
  }

I have all the verteces in a PShape s, so I use those to write to the stl. Since the x,y,z coordinates have to be in a 32 bit floating point number, I convert them using Float.floatToIntBits. I then bitshift them because .write only writes the 8 least significant bits (see here). The four that I write after the header is the number of triangles. The program makes an stl file, but the file doesn't work, any idea where my mistake is?