1 files changed, 5 insertions, 0 deletions

diff --git a/x-carriage.scad b/x-carriage.scad
index 8a9f0d9..c2552d2 100644
--- a/x-carriage.scad
+++ b/x-carriage.scad
@@ -1,102 +1,107 @@
 slide_tolerance = .3;
 play_tolerance=.4;
 fit_tolerance = .25;
 
         bearings_l = 30;// LM8UU: 25
         bearings_d = 12;// LM8UU: 15
         bearings_m = 2.5;// thickness of the bearing end holder
         bearings_s = 2.5;// 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 + slide_tolerance;
 belts_apart = 12;
 belt_pitch = 2;
+beltholder_chamfer = 1;
 
 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(l=cw+2);
  difference() {
   translate([-cw/2,-belt_width/2,-(rods_apart+bearings_d+bearings_m)/2])
   cube(size=[cw,bearings_d/2+bearings_s+belt_width/2,rods_apart+bearings_d+bearings_m]);
 
   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);
    translate([-cw/2-1,-belt_width,-(bearings_d-bearings_m)/2]) cube(size=[cw+2,belt_width,bearings_d-bearings_m]);
   }
 
   difference() {
    gap=belts_apart/6;
    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,$fn=30);
      translate([cw/2,0,belts_apart/2]) mirror([0,0,1]) belt(width=belt_width+2,l=cw/2+2,tolerance=fit_tolerance);
     }
     bgap = belt_thickness+belt_tooth+fit_tolerance;
     r1 = (belts_apart/3-bgap)/2;
     hull() for(x=[mounting_holes_apart/2,x1])
      translate([x,0,-r1-bgap])
      rotate([90,0,0]) cylinder(r=r1,h=belt_width+2,center=true,$fn=30);
    }
   } // 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);
   }
+  ccs = (belt_thickness+2*beltholder_chamfer)/sqrt(2);
+  translate([0,-belt_width/2,belts_apart/2+belt_thickness/2-fit_tolerance/2])
+  rotate([45,0,0]) cube(size=[cw+2,ccs,ccs],center=true);
+
  } // difference
 }
 
 print=false;
 if(print) rotate([-90,0,0]) xcarriage();
 else xcarriage();