diff --git a/bushing.jscad b/bushing.jscad
index 806a2bc..34e1867 100644
--- a/bushing.jscad
+++ b/bushing.jscad
@@ -2,9 +2,15 @@
 // author     : Tim Farrell
 // license    : MIT License
 // revision   : 3
-// tags       : Rubber
+// tags       : TPU
 // file       : bushing.jscad
 
+const { polygon, cylinder, torus } = require('@jscad/modeling').primitives;
+const { extrudeLinear } = require('@jscad/modeling').extrusions;
+const { translate, rotateZ } = require('@jscad/modeling').transforms;
+const { subtract, union } = require('@jscad/modeling').booleans
+
+
 function getParameterDefinitions () {
   return [
     {name: 'overhang', type: 'float', initial: 7, min: 1, max: 40, step: 1, caption: 'Overhang'},
@@ -24,27 +30,35 @@ function knurling(p) {
     const bushing_radius = p.bushing_diameter / 2;
     const thread_radius = bushing_radius * 0.72
     const twist_angle = 45;
-    const overlap = 2;
+    const overlap = 1;
     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]
-    ]);
+    const square = polygon({points: [
+      [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])
-        );
+      knurls.push(
+        translate(
+          [0, 0, -p.bushing_height/2],
+          rotateZ(
+            2 * Math.PI * i / threads,
+            [extrudeLinear({height: p.bushing_height, twistAngle: twist, twistSteps: 120}, square)]
+          )
+        )
+      );
+      knurls.push(
+        translate(
+          [0, 0, -p.bushing_height/2],
+          rotateZ(
+            2 * Math.PI * i / threads,
+            [extrudeLinear({height: p.bushing_height, twistAngle: -twist, twistSteps: 120}, square)]
+          )
+        )
+      );
     }
     return union(...knurls);
 }
@@ -54,17 +68,17 @@ function donut(p) {
     const outer_radius = p.overhang + p.host_hole_diameter/2 - inner_radius;
     const z_offset = p.bushing_height/2 - (p.bushing_height/2 - p.host_hole_height/2);
     return union(
-        torus({ ri: inner_radius, ro: outer_radius }).translate([0, 0, z_offset]),
-        torus({ ri: inner_radius, ro: outer_radius }).translate([0, 0, -z_offset])
+        translate([0, 0, z_offset], torus({ innerRadius: inner_radius, outerRadius: outer_radius })),
+        translate([0, 0, -z_offset], torus({ innerRadius: inner_radius, outerRadius: outer_radius }))
     );
 }
 
 function bushing_main(p) {
     const outer_radius = p.overhang + p.host_hole_diameter/2;
     const main_cylinder = cylinder({
-        r: outer_radius - (p.taper ? (p.bushing_height - p.host_hole_height) / 2 : 0),
-        h: p.bushing_height,
-        center: true
+        radius: outer_radius - (p.taper ? (p.bushing_height - p.host_hole_height) / 2 : 1),
+        height: p.bushing_height,
+        center: [0, 0, 0]
     });
     if (p.taper) {
         return union(
@@ -79,14 +93,14 @@ function host_hole(p) {
     const inner_radius = p.host_hole_diameter/2;
     const outer_radius = p.overhang + inner_radius;
     
-    return difference(
-        cylinder({r: outer_radius, h: p.host_hole_height, center: true}),
-        cylinder({r: inner_radius, h: p.host_hole_height, center: true})
+    return subtract(
+        cylinder({radius: outer_radius, height: p.host_hole_height, center: [0, 0, 0]}),
+        cylinder({radius: inner_radius, height: p.host_hole_height, center: [0, 0, 0]})
     );
 }
 
 function bushing_sleeve(p) {
-    const sleeve = cylinder({r: p.bushing_diameter/2, h: p.bushing_height, center: true});
+    const sleeve = cylinder({radius: p.bushing_diameter/2, height: p.bushing_height, center: [0, 0, 0]});
     if (p.knurling) {
         return union(sleeve, knurling(p));
     }
@@ -94,9 +108,12 @@ function bushing_sleeve(p) {
 }
 
 function main(p) {
-    return difference(
-        bushing_main(p),
-        host_hole(p),
-        bushing_sleeve(p)
+  return subtract(
+      bushing_main(p),
+      host_hole(p),
+      bushing_sleeve(p)
     );
 }
+
+
+module.exports = { main, getParameterDefinitions }
\ No newline at end of file