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
@@ -152,230 +152,243 @@ module the_extruder(
     
     // idler space and mounting hole
     place_idler() {
      difference() {
       cylinder(d=idler_d+idler_clearance*2,h=idler_h+idler_v_tolerance,center=true,$fn=60);
       if(supports) for(y=[-lsd/2+extrusion_width:(lsd-2*extrusion_width)/3:lsd/2-extrusion_width])
        translate([-lsd/2-1,y-extrusion_width/2,-idler_h/2-idler_v_tolerance/2-1])
        cube(size=[lsd+2,extrusion_width,idler_h+idler_v_tolerance+2]);
      }
      cylinder(d=mount_screw_d+mount_screw_d_tolerance,h=lever_thickness+2,center=true,$fn=30);
      translate([0,0,lever_thickness/2-mount_screwhead_h]) 
      cylinder(d=mount_screwhead_d,h=mount_screwhead_h+1,$fn=fnd*mount_screwhead_d);
     }
     // mounting screw hole
     translate([mount_d/2,0,0])
     cylinder(d=mount_screw_d+mount_screw_d_tolerance,h=lever_thickness+2,center=true,$fn=fnd*mount_screw_d);
     
     // lever end
     translate([mount_d/2,0,0]) rotate([0,90,0]) {
      translate([0,-longwing,lsd/2]) finger_indent(d=lever_thickness-1,r=15);
      translate([0,-longwing,0])
      mirror([0,0,1])
      difference() {
       cylinder(d=spring_d+spring_d_clearance,h=lsd,$fn=fnd*(spring_d+spring_d_clearance));
       sphere(d=spring_d*3/4,$fn=fnd*spring_d*3/4);
      }
     }//rotate-translate
    }//difference
    // bridging patch
    place_idler()
    translate([0,0,lever_thickness/2-mount_screwhead_h])
    mirror([0,0,1])
    cylinder(d=mount_screwhead_d,h=layer_height);
   }//translate
  }//lever module
  
  module body() {
   difference() {
    union() {
    cylinder(d=gearbox_d,h=body_h,$fn=fnd*gearbox_d);
     // finger and spring support
     fsw = gearbox_d-(gearbox_d-mount_d)/2-spring_lc;
     translate([-gearbox_d/2,0,0]) difference() {
      union() {
       hull() {
        translate([0,-longwing,ls_z])
        rotate([0,90,0])
        cylinder(d=lever_thickness,h=fsw,$fn=fnd*lever_thickness);
        hh=body_h-ls_z;
        translate([0,0,ls_z-lever_thickness/2])
        mirror([0,1,0]) cube(size=[fsw,longwing-hh+lever_thickness/sqrt(2),hh+lever_thickness/2]);
        hhh=ls_z;
        translate([0,0,0])
        mirror([0,1,0]) cube(size=[fsw,longwing-hhh+lever_thickness/sqrt(2),hhh+lever_thickness/2]);
       }
      }
      translate([0,-longwing,ls_z]) rotate([0,-90,0]) {
       if(!tensioner) finger_indent(d=lever_thickness-1,r=15); else {
        if(debug) translate([0,-lever_thickness/2-1,-gearbox_d]) cube(size=[body_h/2+1,lever_thickness/2+1,gearbox_d+2]);
        mirror([0,0,1]) {
         translate([0,0,st_shell])
         hull() for(o=[0,spring_d]) translate([0,-o,0])
         rotate([0,0,30])
         cylinder(d=st_nut_d,h=st_nut_h,$fn=6);
         translate([0,0,-1]) cylinder(d=st_screw_d,h=fsw+2,$fn=fnd*st_screw_d);
         bigd = spring_d+spring_d_clearance;
         hf = (bigd-st_screw_d)/2;
         translate([0,0,st_shell+st_nut_h+st_shell-epsilon])
         cylinder(d1=st_screw_d,d2=bigd,
          h=hf+epsilon, $fn=fnd*bigd);
         translate([0,0,st_shell+st_nut_h+st_shell+hf-epsilon])
         cylinder(d=bigd,h=fsw+1,$fn=fnd*bigd);
        }
       }
      }
     } // translate
     
     // pushfit bracket
     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-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() {
     cylinder(d1=smalld,d2=bigd,h=hf,$fn=fnd*bigd);
     translate([0,0,hf-epsilon])
     cylinder(d=bigd,h=hf*2,$fn=fnd*bigd);
    }
    translate([0,0,-epsilon])
    cylinder(d=st_screw_d,h=2*hf+epsilon,$fn=fnd*st_screw_d);
   }
  }
 
  module knob() {
   ch = knob_indent_d/2;
   translate([0,0,body_h+epsilon]) {
    mirror([0,0,1]) translate([0,0,-epsilon]) {
     difference() {
      cylinder(d=pulley_d,h=knob_bore_l,$fn=fnd*pulley_d);
      translate([0,0,-1]) difference() {
       cylinder(d=bore_d+knob_bore_d_tolerance,h=knob_bore_l+2);
       translate([-bore_d/2-1,bore_dd-bore_d/2+knob_bore_d_tolerance/2,-1])
       cube([bore_d+2,bore_d/2,knob_bore_l+4]);
      }
     }
    }
    difference() {
     union() {
      cylinder(d1=gearbox_d-2*ch,d2=gearbox_d,h=ch+epsilon,$fn=fnd*gearbox_d);
      translate([0,0,ch])
      cylinder(d=gearbox_d,h=knob_h-2*ch+epsilon,$fn=fnd*gearbox_d);
      translate([0,0,knob_h-ch])
      cylinder(d1=gearbox_d,d2=gearbox_d-2*ch,h=ch,$fn=fnd*gearbox_d);
     }
     for(a=[0:360/knob_indents:359]) rotate([0,0,a])
      translate([0,gearbox_d/2,-1])
      cylinder(d=knob_indent_d,h=knob_h+2,$fn=fnd*knob_indent_d);
    }
   }
  }//knob module
 
  mirrorleft()
  if(what=="lever") color("green",0.7) lever();
  else if(what=="body") color("yellow",0.7) body();
  else if(what=="knob") color("red",0.7) knob();
  else if(what=="springpad") color("blue",0.7) springpad();
  else if(what=="both") {
   color("green",0.7) lever();
   color("yellow",0.7) body();
  }else{
   color("green",0.7) lever();
   color("yellow",0.7) body();
   color("red",0.7) knob();
   color("blue",0.7) springpad();
  }
 }
 
 the_extruder(what="both",left=false);