add magnet dummy to save magnets.

Author: gluap

README.md

@@ -201,6 +201,14 @@ the magnets.
 
 ![Mounting/HandlebarRail](./render/thumbnails/Mounting/HandlebarRail.png)
 
+An alternative Handlebar rail can be mounted like most bike computers with a
+rubber o ring;
+![Mounting/HandlebarRailOring](./render/thumbnails/Mounting/HandlebarRailOring.png)
+
+Often you find magnets where one magnet is strong enough for your display - you
+can use a platic decoy to save on magnets in these cases
+![Mounting/DisplayMagnetDummy](./render/thumbnails/Mounting/DisplayMagnetDummy.png)
+
 #### Bike rack mount
 
 The bike rack mount can be used to attach a "Top Rider" main case to a standard

src/Mounting/HandlebarRailOring.scad

@@ -0,0 +1,99 @@
+include <../../variables.scad>
+
+use <../../lib/Round-Anything/polyround.scad>
+use <../../lib/utils.scad>
+
+module HandlebarRailRail() {
+  mirrorCopy([1, 0, 0])
+  difference() {
+    mirror([0, 1, 0])
+    rotate([90, 0, 0])
+    linear_extrude(HandlebarRail_rail_length, convexity=3)
+    polygon([
+      [0, 0],
+      [8, 0],
+      [8, 7],
+      [8 - 1.95, HandlebarRail_rail_total_height - 1.25 - 1.95 - 1.3],
+      [8 - 1.95, HandlebarRail_rail_total_height - 1.95 - 1.3],
+      [8, HandlebarRail_rail_total_height - 1.3],
+      [8, HandlebarRail_rail_total_height],
+      [0, HandlebarRail_rail_total_height],
+    ]);
+
+    translate([8-2, HandlebarRail_rail_length, -2])
+    rotate([0, 0, -45])
+    translate([-1, 0, 0])
+    cube([10, 10, 20]);
+  }
+}
+
+module HandlebarRailStopblock() {
+  difference() {
+    hull() {
+      for(i=[-1,1])for(j=[0,1])
+      translate([i*(HandlebarRail_stopblock_width/2-HandlebarRail_stopblock_radius), j*(-HandlebarRail_stopblock_depth+2*HandlebarRail_stopblock_radius)-HandlebarRail_stopblock_radius, 0])
+      cylinder(r=HandlebarRail_stopblock_radius, h=HandlebarRail_stopblock_height);
+    }
+
+    // cutout for magnets
+    translate([0, -HandlebarRail_stopblock_magnet_wall_thickness, 0]) {
+      // hole for pushing magnet out
+      translate([0, -HandlebarRail_stopblock_magnet_thickness*1.5, 0])
+      cylinder(d=HandlebarRail_stopblock_magnet_thickness, h=HandlebarRail_stopblock_height);
+
+      translate([0, -HandlebarRail_stopblock_magnet_thickness, HandlebarRail_rail_total_height + HandlebarRail_stopblock_magnet_lift + HandlebarRail_stopblock_magnet_height / 2])
+      cube([HandlebarRail_stopblock_magnet_width, HandlebarRail_stopblock_magnet_thickness * 2, HandlebarRail_stopblock_magnet_height], center=true);
+
+      #translate([0, -HandlebarRail_stopblock_magnet_thickness*1.5, HandlebarRail_stopblock_height-3+epsilon])
+      cube([HandlebarRail_stopblock_magnet_width, HandlebarRail_stopblock_magnet_thickness, 6], center=true);
+    }
+  }
+}
+
+module HandlebarRailZiptieCutout(width) {
+  translate([0, width, 0])
+  rotate([90, 0, 0])
+  difference() {
+    cylinder(r=HandlebarRail_tube_radius*1.3, h=width, $fn=$fn*2);
+    cylinder(r=HandlebarRail_tube_radius*1.2, h=width, $fn=$fn*2);
+  }
+}
+
+module HandlebarRailOringCutout(r_torus=9.2,r_oring=1.7) {
+    rotate_extrude()translate([r_torus,0,0])circle(r_oring);
+    difference(){hull(){cylinder(h=epsilon,r=r_torus+r_oring);
+        translate([0,5,10])cylinder(h=epsilon,r=r_torus+r_oring);}
+        hull(){cylinder(h=epsilon,r=r_torus-r_oring);
+        translate([0,5,10])cylinder(h=epsilon,r=r_torus-r_oring);}}
+}
+
+module HandlebarRail() {
+  difference() {
+    union() {
+      HandlebarRailRail();
+      HandlebarRailStopblock();
+    }
+
+    translate([0, 0, -HandlebarRail_tube_radius + HandlebarRail_tube_indent]) {
+      union () {
+        // tube
+        translate([0, 50, 0])
+        rotate([90, 0, 0])
+        cylinder(r=HandlebarRail_tube_radius, h=100);
+        #translate([7.6,HandlebarRail_rail_length/2,HandlebarRail_tube_radius - HandlebarRail_tube_indent+5])
+        rotate([0,10,0])HandlebarRailOringCutout(r_torus=6,r_oring=1.2);
+          translate([-7.6,HandlebarRail_rail_length/2,HandlebarRail_tube_radius - HandlebarRail_tube_indent+5])
+        rotate([0,-10,0])HandlebarRailOringCutout(r_torus=6,r_oring=1.3);
+      }
+    }
+  }
+}
+
+if (orient_for_printing) {
+  translate([0, 0, HandlebarRail_stopblock_depth])
+  rotate([90, 0, 0])
+  HandlebarRail();
+} else {
+  rotate([0, 0, 90])
+  HandlebarRail();
+}