knob.hs

#!/usr/bin/env stack
{- stack script --resolver lts-22.6 
    --package linear
    --package waterfall-cad
    --extra-dep waterfall-cad-0.3.0.0
    --extra-dep opencascade-hs-0.3.0.0
-}

-- short-description: Tommy's Knobs

-- description: [A pal of mine](https://www.tommyp.org/) DJs under the name [Syntax Terror](https://soundcloud.com/syntax-terrorist).
-- description: 
-- description: A while back, he contacted me about printing some replacement dials for his [Traktor Kontrol X1 MK2](https://www.native-instruments.com/en/products/traktor/dj-controllers/traktor-x1/), as these had apparently fallen off during transit.
-- description: 
-- description: He sent me a list of possible knob designs from Thingiverse.
-- description: 
-- description: Now, I'm broadly of the opinion that the point of having a 3d printer is that you can make _custom parts_.
-- description: Thingiverse is great, but if you're just going to print stuff from Thingiverse all the time, you'd be better off with an Alibaba account. 
-- description: 
-- description: With this in mind, I thought I'd have a go at designing some custom knobs, instead.
-- description: 
-- description: This meant I was able to use the line "I've got some knobs here with your name on them", while we were arranging postage.
-- description: 
-- description: While I'm relatively happy with how these came out, I regret not playing around with the bevel radius and number of cuts a little more than I did.
-- image: https://doscienceto.it/blog/photos/knobs-01.jpg
-- image: https://doscienceto.it/blog/photos/traktor_kontrol.jpg

import qualified Waterfall
import Linear 

shaft :: Waterfall.Solid
shaft = 
    let r = 3 
        h = 20 
        cutOff = 2
    in (Waterfall.scale (V3 r r h) Waterfall.unitCylinder) `Waterfall.difference` 
        (Waterfall.translate (cutOff *^ unit _y) $ Waterfall.scale (V3 h h (h*3)) $ Waterfall.translate (0.5 *^ unit _y) $ Waterfall.centeredCube)

knob :: Waterfall.Shape -> Waterfall.Solid
knob t = 
    let rInner = 19/2
        h = 19
        fillet = Waterfall.roundConditionalFillet (\(V3 _ _ z, V3 _ _ z') -> if z > h/2 && z' > h/2 then Just 5 else Nothing)
        cutR = 1.75
        cutN = 8
        cuts = Waterfall.rotate (unit _z) (pi/cutN) $ mconcat $ take 10 $ iterate (Waterfall.rotate (unit _z) (2*pi/cutN)) $ Waterfall.translate (rInner *^ unit _y) $ Waterfall.scale (V3 cutR cutR (h*3)) $ Waterfall.centeredCylinder 
        plainCyl = fillet $ Waterfall.scale (V3 rInner rInner h) $ Waterfall.unitCylinder
        rOuter = 21/2
        baseH = 2
        coneS = rOuter + baseH
        coneGrad = 0.75
        baseCone = Waterfall.scale (V3 coneS coneS (coneS * coneGrad)) $ Waterfall.translate (unit _z) $ Waterfall.rotate (unit _x) pi $ Waterfall.unitCone
        base = (Waterfall.scale (V3 rOuter rOuter (h/2)) Waterfall.unitCylinder) `Waterfall.intersection` baseCone
        shaft' = Waterfall.translate ((h - 20 - 2) *^ unit _z) $ shaft

        tDepth = 0.5
        text = Waterfall.translate ((h- tDepth*9) *^ unit _z) $ Waterfall.prism (tDepth *10) t
    in  (((plainCyl `Waterfall.difference` cuts) `Waterfall.union` base) `Waterfall.difference` shaft') `Waterfall.union` text


main :: IO ()
main = do
    let stlRes = 0.05
    font <- Waterfall.fontFromSystem "monospace" Waterfall.Regular 5
    Waterfall.writeSTL stlRes "knob-syntax.stl" (knob $ Waterfall.text font "syntax")
    Waterfall.writeSTL stlRes "knob-terror.stl" (knob $ Waterfall.text font "terror")