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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,$fn=6);
}
translate([0,-1,0])
cube(size=[l,width+2,thickness+tooth+1]);
}
}
module xcarriage() {
cw = bearings_l+2*bearings_m; // carriage width
% for(mz=[0,1]) mirror([0,0,mz]) translate([0,0,-belts_apart/2]) belt(l=cw+2);
difference() {
translate([-cw/2,-belt_width/2,-(rods_apart+bearings_d+bearings_m)/2])
cube(size=[cw,bearings_d/2+bearings_s+belt_width/2,rods_apart+bearings_d+bearings_m]);
for(sz=[-1,1]) translate([0,0,sz*rods_apart/2]) {
rotate([0,90,0])
cylinder(d=bearings_d,h=bearings_l,center=true,$fn=60);
translate([0,-bearings_d/2,0])
cube(size=[bearings_l,bearings_d,bearings_d],center=true);
rotate([0,90,0]) cylinder(d=bearings_d-bearings_m,h=cw+2,center=true,$fn=60);
translate([-cw/2-1,-belt_width,-(bearings_d-bearings_m)/2])
cube(size=[cw+2,belt_width,bearings_d-bearings_m]);
for(sx=[-1,1]) translate([sx*bearings_l/4,0,0]) {
rotate([0,90,0]) difference() {
cylinder(d=tiehole_od,h=tiehole_w,center=true,$fn=60);
cylinder(d=tiehole_id,h=tiehole_w+2,center=true,$fn=60);
}
translate([0,-tiehole_od/2,0])
cube(size=[tiehole_w,tiehole_od,tiehole_od],center=true);
} // translate for(sx)
} // for(sz)
difference() {
gap=belts_apart/6;
translate([0,-.5,-gap/2])
cube(size=[cw+2,belt_width+2,belts_apart+2*belt_thickness+gap],center=true);
for(mx=[0,1]) mirror([mx,0,0]) {
ofc = mounting_holes_apart/2+screwhead_d/2+belt_thickness+belt_tooth+play_tolerance; // offset from center
r=1;
x0 = ofc+r; x1=cw/2-r;
z0 = r; z1 = belts_apart/2-belt_thickness;
difference() {
hull() for(x=[x0,x1]) for(z=[z0,z1])
translate([x,0,z])
rotate([90,0,0]) cylinder(r=r,h=belt_width+2,center=true,$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();
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