module min_lines(D) {
    divisor=60;
    len=D/20;
    Dist=D-len;
    for(dot=[0:6:360]){
        translate([sin(dot)*Dist,cos(dot)*Dist,0])
        color("black")
        rotate([0,0,-dot]) // negative z rotates towards outer circle
        if (dot % 90 == 0){ 
            divisor = 30;
            translate([0,D/divisor,0]) // h
                square([D/divisor,D/divisor*4], center=true);
        }
        else { 
            divisor = 60;
            translate([0,D/divisor*2,0]) // min
                square([D/divisor,D/divisor*4], center=true);
        }
    }
}

min_lines(240);