cutout on the back side

in the unfortunate event of filament grinding it may serve as an
escape way for filament powder

1 files changed, 13 insertions, 0 deletions

diff --git a/another.scad b/another.scad
index 4af7d29..38a9aae 100644
--- a/another.scad
+++ b/another.scad
@@ -232,96 +232,109 @@ module the_extruder(
     rotate([-90,0,0])
     translate([0,0,mount_d/sqrt(2)/2+mount_screw_d-gearbox_d/2/*TODO:*/])
     cylinder(r=min(body_h-filament_elevation,filament_elevation)/sin(60)-epsilon,h=pf_h(pf)+gearbox_d/2/*TODO:*/,$fn=6);
    }//union (first child of difference)
 
    // protrusion
    translate([0,0,-1])
    cylinder(d=protrusion_d+protrusion_tolerance_h,h=protrusion_h+protrusion_tolerance_v+1,$fn=fnd*(protrusion_d+protrusion_tolerance_h));
    // mount screw holes
    for(zr=[0:90:359]) rotate([0,0,zr]) translate([mount_d/2,0,0]) {
     translate([0,0,mount_screw_l-mounthole_depth/2-layer_height-1])
     mirror([0,0,1])
     cylinder(d=mount_screw_d+mount_screw_d_tolerance,
              h=mount_screw_l-mounthole_depth/2-layer_height+1,
 	     $fn=fnd*(mount_screw_d+mount_screw_d_tolerance));
     translate([0,0,mount_screw_l-mounthole_depth/2])
     cylinder(d=mount_screwhead_d,h=body_h+1,$fn=fnd*mount_screwhead_d);
    }//for
    // pushfit
    translate([0,0,filament_elevation])
    rotate([0,0,45]) translate([pulley_d/2,0,0])
    rotate([-90,0,0])
    translate([0,0,mount_d/sqrt(2)/2+mount_screw_d+epsilon])
    rotate([0,0,180]) {
     pushfit(pf);
     cylinder(d=filament_guide_d,h=gearbox_d,center=true,$fn=fnd*filament_guide_d);
     translate([0,-filament_guide_d/2/sqrt(2),0])
     rotate([0,0,45])
     cube(size=[filament_guide_d/2,filament_guide_d/2,gearbox_d],center=true);
    }//rotate translate rotate translate rotate translate
    // pulley
    cylinder(d=pulley_d+pulley_clearance,h=body_h+1,$fn=fnd*(pulley_d+pulley_clearance));
    // leverspace
    hull() for(x=[0,gearbox_d])
    rotate([0,0,45])
    translate([x,0,ls_z-ls_h/2])
    cylinder(d=idler_d+idler_clearance,h=ls_h,$fn=fnd*(idler_d+idler_clearance));
 
    // idler clearance
    a=cos(45)*(pulley_d+idler_d)/2;
    b=mount_d/2-a;
    x=sqrt(pow(a,2)+pow(b,2));
    translate([mount_d/2,0,ls_z])
    intersection() {
     r = x+idler_d/2+idler_clearance;
     cylinder(r=r,h=ls_h,center=true);
     translate([-r-1,0,-ls_h/2-1]) cube(size=[2*r+2,r+1,ls_h+2]);
    }
+
+   // back side cutout
+   a0 = asin((mount_screwhead_d+2*extrusion_width)/mount_d);
+   a1 = atan((longwing-lever_thickness/2)/(gearbox_d/2));
+   translate([0,0,ls_z]) hull() {
+    rotate([0,0,-180+a0])
+    rotate_extrude(angle=a1-a0)
+    translate([0,-ls_h/2])
+    square([sqrt(pow(gearbox_d/2,2)+pow(longwing-lever_thickness/2,2))+1,
+            ls_h]);
+    cylinder(d=bore_d/2/*TODO:recalculate angles based on this,
+                         too lazy to do that now*/,
+             h=ls_h,center=true);
    }
    
    rotate([0,0,-45])
    translate([0,0,ls_z-ls_h/2])
    cube(size=[gearbox_d,gearbox_d,lever_thickness+lever_v_clearance]);
    translate([0,0,ls_z-ls_h/2]) {
     translate([mount_screwhead_d/2,0,0])
     mirror([0,1,0])
     cube(size=[gearbox_d,gearbox_d/2+1,lever_thickness+lever_v_clearance]);
    }
    //translate([-mount_d/2,-longwing,filament_elevation])
    if(!tensioner) /* XXX: this seems to be bullshit, but it's so old, that it's historical bullshit */
    translate([mount_d/2,-longwing,filament_elevation])
    rotate([0,-90,0]) difference() {
     cylinder(d=spring_d+spring_d_clearance,h=spring_lc+spring_dl,$fn=fnd*(spring_d+spring_d_clearance));
     translate([0,0,spring_lc+spring_dl]) sphere(d=spring_d*3/4,$fn=fnd*spring_d*3/4);
    }
     
   }//difference
 
   if(supports) intersection() {
    difference() {
     translate([0,0,ls_z-ls_h/2-epsilon])
     cylinder(d=gearbox_d,h=ls_h+2*epsilon,$fn=fnd*gearbox_d);
     cylinder(d=pulley_d+pulley_clearance,h=body_h+1,$fn=fnd*(pulley_d+pulley_clearance));
    }
    // supports
    // TODO: hardcoded stuff below…
    if(false) { // parallel
     for(y=[-gearbox_d:4:gearbox_d])
      translate([0,y-extrusion_width/2,0])
      cube(size=[gearbox_d,extrusion_width,body_h]);
    }else{ // radial
     for(zr=[-65:(65+50)/7:50])
      rotate([0,0,zr]) translate([0,-extrusion_width/2,0])
      cube(size=[gearbox_d,extrusion_width,body_h]);
    }
   }
 
  }//body module
 
  module springpad() {
   smalld=st_screw_d+2*extrusion_width;
   bigd = spring_d+spring_d_clearance/2;
   hf = (bigd-smalld)/2;
   translate([-gearbox_d/2+st_shell+st_nut_h+st_shell+smalld,-longwing,filament_elevation])
   rotate([0,90,0]) difference() {
    union() {