Filament Gauge

//Math by https://www.thingiverse.com/thing:1880517
//https://jscalc.io/calc/1Cj6c1zxnr4q8Tzw
diamInnerHole=85;
diamInnerSpool = 91;
diamOuterSpool = 200;
widthScale=25;
diamFilament=1.75;
innerWidth=54;

translate([0,0,-1])
linear_extrude(height=0.24+0.2+0.2+0.2){
  difference(){
    union(){
      translate([-diamOuterSpool/2,-widthScale/2]) square(size=[diamOuterSpool,widthScale]);

      circle(d=diamInnerHole);
    }
  circle(d=diamInnerHole-4);
  }
}

function getLength(d2) = (pow(d2,2)-pow(diamInnerSpool,2))*PI*innerWidth*0.8/4/pow(diamFilament,2)/1000;

maxFilament = getLength(diamOuterSpool);

function getDiam(L) = sqrt(pow(diamInnerSpool,2)+((L*4*1000*pow(diamFilament,2))/(PI*innerWidth*0.8)));

echo (getDiam(maxFilament));

perc = 0.75;
for (perc=[0.02, 0.1, 0.25, 0.37, 0.5, 0.75]){
rotate([90,0,0]) translate([getDiam(perc*maxFilament)/2,0,-widthScale/2]) cylinder(h=widthScale, r=1);
rotate([0,0,90]) translate([-widthScale/2+1.5,getDiam(perc*maxFilament)/2,0]) linear_extrude(height=1) text(str(perc*100,"% - ",round(perc*maxFilament),"m"), size=3, font="Liberation Sans:style=Bold");
rotate([90,0,0]) translate([-getDiam(perc*maxFilament)/2,0,-widthScale/2]) cylinder(h=widthScale, r=1);
rotate([0,0,-90]) translate([-widthScale/2+1.5,getDiam(perc*maxFilament)/2,0]) linear_extrude(height=1) text(str(perc*100,"% - ",round(perc*maxFilament),"m"), size=3, font="Liberation Sans:style=Bold");
}