From 38e29eb868018ccb863dacd63dd6a686d30abffd Mon Sep 17 00:00:00 2001
From: Timothy Farrell <tim@thecookiejar.me>
Date: Mon, 30 Dec 2019 12:55:22 -0600
Subject: [PATCH] Add inner sleeve knurling option

---
 bushing.jscad | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/bushing.jscad b/bushing.jscad
index 0ed7106..806a2bc 100644
--- a/bushing.jscad
+++ b/bushing.jscad
@@ -12,11 +12,43 @@ function getParameterDefinitions () {
     {name: 'host_hole_height', type: 'float', initial: 0.8, caption: 'Host hole height'},
     {name: 'bushing_height', type: 'float', initial: 4, min: 1, max: 40, step: 1, caption: 'Bushing height'},
     {name: 'bushing_diameter', type: 'float', initial: 10, min: 1, max: 40, step: 1, caption: 'Bushing diameter'},
-    {name: 'taper', type: 'checkbox', checked: true, caption: 'Taper Edges?'}
+    {name: 'taper', type: 'checkbox', checked: true, caption: 'Taper Edges?'},
+    {name: 'knurling', type: 'checkbox', checked: false, caption: 'Add knurling?'}
   ];
 }
 
 
+function knurling(p) {
+    const knurls = [];
+
+    const bushing_radius = p.bushing_diameter / 2;
+    const thread_radius = bushing_radius * 0.72
+    const twist_angle = 45;
+    const overlap = 2;
+    const twist = twist_angle * p.bushing_height / thread_radius;
+    const threads = 360 / twist_angle * overlap;
+    const triangle = polygon([
+        [thread_radius, thread_radius],
+        [0, thread_radius],
+        [0, 0],
+        [thread_radius, 0]
+    ]);
+
+    for (let i=0; i < threads; ++i) {
+        knurls.push(
+            linear_extrude({height: p.bushing_height, twist, slices: 30}, triangle)
+            .rotateZ(360 / threads * i)
+            .translate([0, 0, -p.bushing_height/2])
+        );
+        knurls.push(
+            linear_extrude({height: p.bushing_height, twist: -twist, slices: 30}, triangle)
+            .rotateZ(360 / threads * i)
+            .translate([0, 0, -p.bushing_height/2])
+        );
+    }
+    return union(...knurls);
+}
+
 function donut(p) {
     const inner_radius = (p.bushing_height - p.host_hole_height) / 2;
     const outer_radius = p.overhang + p.host_hole_diameter/2 - inner_radius;
@@ -54,7 +86,11 @@ function host_hole(p) {
 }
 
 function bushing_sleeve(p) {
-    return cylinder({r: p.bushing_diameter/2, h: p.bushing_height, center: true});
+    const sleeve = cylinder({r: p.bushing_diameter/2, h: p.bushing_height, center: true});
+    if (p.knurling) {
+        return union(sleeve, knurling(p));
+    }
+    return sleeve;
 }
 
 function main(p) {