From 41c8af93ec2bf962e3a18b8fe7602d2cf676189d Mon Sep 17 00:00:00 2001
From: Michael Krelin <hacker@klever.net>
Date: Fri, 15 Jul 2016 17:00:13 +0000
Subject: reworked carriage.

Begin not an engineer, but developer I couldn't stand the code. Though
I also started to resolve some engineering issues and being developer and
not an engineer, I didn't do that well, but that's a start…
---
(limited to 'x-carriage.scad')

diff --git a/x-carriage.scad b/x-carriage.scad
new file mode 100644
index 0000000..a546bb7
--- a/dev/null
+++ b/x-carriage.scad
@@ -0,0 +1,111 @@
+slide_tolerance = .3;
+play_tolerance=.4;
+fit_tolerance = .2;
+
+bearings_l = 25;	// 15;
+bearings_d = 15;	// 12;
+bearings_m = 2.5;	// thickness of the bearing end holder
+bearings_s = 4.5;	// the minimum shell between bearings and carriage front
+
+rods_apart = 45;
+rod_d = 8;
+
+mounting_holes_from_top = [	// the offsets of mounting holes on the back
+ [0, 20], [-4.5,10], [4.5,10]
+];
+mounting_holes_apart = mounting_holes_from_top[2][0]-mounting_holes_from_top[1][0];
+
+belt_tooth=0.70;
+belt_thickness=0.75;
+belts_thickness = belt_thickness*2+belt_tooth+0.5;
+belt_width = 6;
+belts_apart = 12;
+belt_pitch = 2;
+
+tiehole_id = bearings_d+3;
+tiehole_od = bearings_d+10;
+tiehole_w = 4;
+
+screw_d = 3;
+screwhead_d = 5.5;
+screwhead_h = 3;
+
+module belt(pitch=belt_pitch,width=belt_width,thickness=belt_thickness,tooth=belt_tooth,l=100,tolerance=0) {
+ translate([-l/2,-width/2,-thickness])
+ intersection() {
+  union() {
+   cube(size=[l,width,thickness+tolerance]);
+   for(x=[0:pitch:l/2]) for(s=[-1,1])
+    translate([l/2+s*x,0,thickness])
+    rotate([-90,0,0])
+    cylinder(r=tooth+tolerance,h=width,$fn=6);
+  }
+  translate([0,-1,0])
+  cube(size=[l,width+2,thickness+tooth+1]);
+ }
+}
+
+module xcarriage() {
+ cw = bearings_l+2*bearings_m;	// carriage width
+ % for(mz=[0,1]) mirror([0,0,mz]) translate([0,0,-belts_apart/2]) belt();
+ difference() {
+  translate([-cw/2,-belt_width/2,-rods_apart/2-bearings_d/2])
+  cube(size=[cw,bearings_d/2+bearings_s+belt_width/2,rods_apart+bearings_d]);
+
+  for(sz=[-1,1]) translate([0,0,sz*rods_apart/2]) {
+   rotate([0,90,0])
+   cylinder(d=bearings_d,bearings_l,center=true,$fn=60);
+   for(sx=[-1,1]) translate([sx*bearings_l/4,0,0])
+    rotate([0,90,0]) difference() {
+     cylinder(d=tiehole_od,h=tiehole_w,center=true,$fn=60);
+     cylinder(d=tiehole_id,h=tiehole_w+2,center=true,$fn=60);
+    }
+   rotate([0,90,0]) cylinder(d=bearings_d-bearings_m,h=cw+2,center=true,$fn=60);
+  }
+
+  difference() {
+   gap=3;
+   translate([0,-.5,-gap/2])
+   cube(size=[cw+2,belt_width+2,belts_apart+2*belt_thickness+gap],center=true);
+   for(mx=[0,1]) mirror([mx,0,0]) {
+    ofc = mounting_holes_apart/2+screwhead_d/2+belt_thickness+belt_tooth+play_tolerance; // offset from center
+    r=1;
+    x0 = ofc+r; x1=cw/2-r;
+    z0 = r; z1 = belts_apart/2-belt_thickness;
+    difference() {
+     hull() for(x=[x0,x1]) for(z=[z0,z1])
+      translate([x,0,z])
+      rotate([90,0,0]) cylinder(r=r,h=belt_width+2,center=true,$fn=30);
+     translate([cw/2,0,belts_apart/2]) mirror([0,0,1]) belt(width=belt_width+2,l=cw/2+2,tolerance=fit_tolerance);
+    }
+    bgap = belt_thickness+belt_tooth+fit_tolerance;
+    r1 = (belts_apart/3-bgap)/2;
+    echo(r1);
+    hull() for(x=[mounting_holes_apart/2,x1])
+     translate([x,0,-r1-bgap])
+     rotate([90,0,0]) cylinder(r=r1,h=belt_width+2,center=true,$fn=30);
+    dgn= sqrt(pow(x1-x0,2)+pow(z1-z0,2));
+    echo(dgn);
+    translate([x0,0,z0])
+    rotate([90,0,0])
+    * cylinder(r=dgn/2-r-belt_thickness,h=belt_width+2,center=true,$fn=30);
+    /*
+    pd = 4.5;	// post diameter
+    bhd = 5;	// belt holder diameter
+    translate([cw/2-pd/2,0,belts_apart/2-belts_thickness-bhd/2]) cube(size=[pd,belt_width,bhd],center=true);
+    translate([(cw-pd)/2,0,0]) // TODO: z
+    rotate([-90,0,0]) translate([0,0,-1]) cylinder(d=pd,h=belt_width+2,center=true,$fn=30); */
+   }
+  } // difference
+
+  translate([0,0,30/*heatsink height*//2])
+  for(mhft = mounting_holes_from_top) translate([mhft[0],0,-mhft[1]]) {
+   rotate([90,0,0]) cylinder(d=screw_d+2*play_tolerance,h=bearings_d+2*bearings_s+2,center=true,$fn=30);
+   translate([0,belt_width/2+screwhead_h+play_tolerance,0])
+   rotate([90,0,0]) cylinder(d=screwhead_d+2*play_tolerance,h=screwhead_h+play_tolerance+1,$fn=30);
+  }
+ } // difference
+}
+
+xcarriage();
+
--
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