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@rocktronica
Last active January 31, 2023 03:55
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// Size 4-40
screwDiameter = 2.8;
screwHeadDiameter = 5.5;
screwHeadHeight = 2.3;
insertDiameter = 4;
insertThreadedDiameter = 4.45;
insertHeight = 3.5;
standardPotShaftTopHeight = 8;
standardPotShaftTopDiameter = 6;
standardFlattedDepth = standardPotShaftTopDiameter - 4.5;
minimumKnobHeightFromShaft = 2;
minimumKnobHeight = standardPotShaftTopHeight + minimumKnobHeightFromShaft;
potKnobDefaultShimCount = 3;
module pot_knob(
knobDiameter = 15,
knobHeight = minimumKnobHeight,
knobColor = [.1,.1,.1,1],
innerColor = undef,
shaftDiameter = standardPotShaftTopDiameter,
shaftHeight = standardPotShaftTopHeight,
showChamfer = true,
markerHeight = 1,
markerWidth = 2,
markerRotation = 0,
markerColor = "white",
showMarker = true,
invertMarker = false,
shimWidth = 1,
shimLength = .5,
shimCount = potKnobDefaultShimCount,
tightenerDiameter = 0,
recessHeight = 0,
recessDiameter = 0,
flatted = false,
flatDepth = standardFlattedDepth,
flatTolerance = undef,
$fn = 100,
debug = false,
tolerance = .25,
previewGutter = .1
) {
useSkirt = recessHeight > 0 && recessDiameter > 0;
recessHeight = useSkirt ? recessHeight : 0;
recessDiameter = useSkirt ? recessDiameter : 0;
shaftHeight = useSkirt ? shaftHeight + recessHeight : shaftHeight;
innerColor = innerColor == undef
? knobColor
: innerColor;
module standard_pot_flat_cutout(
rotation = -markerRotation,
depth = flatDepth - (flatTolerance == undef ? tolerance : flatTolerance)
) {
width = shaftDiameter + previewGutter * 2;
length = shaftDiameter; // arbitrary
rotate([0, 0, rotation]) {
translate([
width / -2,
-length - (shaftDiameter + tolerance * 2) / 2 + depth,
-previewGutter
]) {
cube([width, length, shaftHeight + previewGutter * 2]);
}
}
}
module outer() {
cylinder(
d = knobDiameter,
h = knobHeight
);
}
module shims() {
offset = shimCount == 1
? 0
: (360 / shimCount / 2) - markerRotation;
for (i = [0 : shimCount]) {
rotate([0, 0, offset + 360 * (i / shimCount)]) {
translate(
[(shimWidth / -2),
shaftDiameter / 2 - shimLength + tolerance,
previewGutter * -2
]) {
cube([
shimWidth,
shimLength * 2,
shaftHeight + previewGutter * 3
]);
}
}
}
}
module inner() {
difference() {
translate([0, 0, -previewGutter]) {
cylinder(
d = shaftDiameter + tolerance * 2,
h = shaftHeight + previewGutter
);
}
if (shimCount > 0) {
shims();
}
if (flatted) {
standard_pot_flat_cutout();
}
} // difference
}
module recess() {
translate([0, 0, -previewGutter]) {
cylinder(
d = recessDiameter + tolerance * 2,
h = recessHeight + previewGutter
);
}
}
module marker() {
z = invertMarker
? knobHeight - markerHeight
: knobHeight;
height = invertMarker
? markerHeight + previewGutter
: markerHeight;
rotate([0, 0, markerRotation * -1]) {
translate([(markerWidth / -2), 0, z]) {
cube([markerWidth, knobDiameter / 2, height]);
}
}
}
module shaft_chamfer() {
chamferDiameter = shaftDiameter + 3;
chamferHeight = chamferDiameter / 2;
translate([0, 0, recessHeight - previewGutter]) {
cylinder(
d1 = chamferDiameter,
d2 = 0,
h = chamferHeight + previewGutter
);
}
}
module tightener_cutout() {
wallDepth = (knobDiameter - shaftDiameter) / 2;
headCavityDepth = max(screwHeadHeight, wallDepth - insertHeight);
minimumBaseBeneathHeadDepth = 2;
translate([0, 0, recessHeight + shaftHeight / 2])
rotate([90, 0, 0]) {
cylinder(
d = tightenerDiameter,
h = knobDiameter
);
if (wallDepth >= headCavityDepth + minimumBaseBeneathHeadDepth) {
translate([0, 0, knobDiameter / 2 - headCavityDepth]) {
cylinder(
d = screwHeadDiameter + tolerance * 2,
h = headCavityDepth + previewGutter
);
}
}
}
}
intersection() {
difference() {
color(knobColor) outer();
color(innerColor) {
inner();
if (showChamfer) {
shaft_chamfer();
}
recess();
if (showMarker && invertMarker) {
marker();
}
if (tightenerDiameter > 0) {
tightener_cutout();
}
}
} // difference
if (debug) {
translate([
knobDiameter / -2 - previewGutter,
knobDiameter / -2 - previewGutter,
-previewGutter
]) {
cube([
knobDiameter / 2 + previewGutter,
knobDiameter + previewGutter * 2,
knobHeight + previewGutter * 2
]);
}
}
}
if (showMarker && !invertMarker) {
color(markerColor) {
marker();
}
}
}
@rocktronica
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Designing Potentiometer Knobs

From the blog post Designing Potentiometer Knobs

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