Build Instructions

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• 1

  Step 1

  Download the scad file from files section and generate the 3d model in openscad, or skip this step and print from the attached .stl file.
  

  OD = 31.9;        //outer width
  OH = 15;        // height of main cylinder
  ID = 5;         //inside diameter for mounting hole
  KD = OD+10;        //outer diameter for knob
  KH = 10;         //height of knob
  SD = 6;         //shaft diameter
  SH = 10;        //shaft height
  
  module knobMain (){
      cylinder(OH,d=OD);      //main cylinder
      //grip cylinder with grip on outside
      translate([0,0,OH+KH/2]) cylinder(KH,d=KD,center=true);
  }
  
  module knobCutout (){
      difference(){
          //cylinder to remove center hole
          translate([0,0,-0.1]) cylinder(h=SH,d=SD);
          //keep the tab on the switch
          #translate([SD/1.5,0,(SH/2)-0.1]) cube([SD,SD,SH], center=true); 
      }
  }
  
  module buildMain (){
      difference(){
          knobMain();
          knobCutout();
          // this cuts out the small indents around the outer edge
          for (i = [0:360/7:360]) {             rotate([0,0,i])
              translate([KD/2,0,OH+KH/2])
              cylinder(KH+0.1,d=KD-OD-2,center=true);
          }
      }
  }
  
  buildMain();

• 2

  Step 2

  You may need to enlarge the inner hole to suit your printer and rotary switch. generate the .stl or use downloaded file. Print 3d part.
  

• 3

  Step 3

  Use sand paper to smooth the corners and printing artifacts if necessary. I use a kitchen stove gas flame to smooth the plastic scuffs after sanding.

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