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Work (not yet completed) on the lower knuckles of the four bar linkage.

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Simon Brooke 2025-09-20 17:49:49 +01:00
parent 1befca0a60
commit 025575a488
3 changed files with 47 additions and 25 deletions
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55
model/fourbar.scad
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@ -34,21 +34,51 @@ module fourbar_leg(length=1000, chord=100, long_skew=30, lat_skew=30) {
}
module fourbar_axle_half( length, chord) {
translate([0, 0, -120])
rotate([82, 0, 180])
module lower_knuckle(chord=100, pivot_radius=12) {
difference() {
cube([chord * 1.5, pivot_radius * 3, chord*.66]);
translate([ chord*0.25, -1, pivot_radius * 2])
cube([chord, pivot_radius * 4, pivot_radius * 4]);
}
}
module fourbar_axle_half( length, chord, long_skew) {
shoulder=650;
lat_skew=30;
rise=8;
// I've got something wrong in computing the half-lower-bar
// length, and I don't know what.
fudge=0;
w = ((length * sin(lat_skew) ) + ( shoulder / 2));
l_hlb= w * (1/cos(rise)) + fudge;
v_offset=l_hlb * sin(rise);
echo("long_skew", long_skew);
translate([0, 0, 0 - v_offset])
rotate([90-rise, 0, 180])
color("black")
airfoil(h=length, L=chord);
airfoil(h=l_hlb, L=chord);
// lower knuckle
translate([-chord, length, -60])
translate([(0 - (chord*1.25)), l_hlb * cos(rise), 30])
rotate([0, long_skew, 0])
color("black")
cube([chord, chord/4, chord/2]);
lower_knuckle(chord, 12);
// wheel
translate([0, length + 50, -50])
translate([-50, l_hlb + 72, -40])
rotate([270, 0, 0])
wheel(iso=451);
wheel(iso=451);
// brake disk
translate([-50, l_hlb + 35, -40])
color("silver")
rotate([90, 0, 0])
cylinder(h=1.5, r=75);
// brake caliper
}
@ -64,11 +94,12 @@ module fourbar(length=1000, chord=100, long_skew=30, lat_skew=30, shoulder=650)
mirror([0, 1, 0])
fourbar_leg(length, chord, long_skew, lat_skew);
fourbar_axle_half(w, chord);
fourbar_axle_half(w, chord, long_skew);
mirror([0, 1, 0])
fourbar_axle_half(w, chord);
fourbar_axle_half(w, chord, long_skew);
}
// fourbar();
// lower_knuckle();
// fourbar();
// fourbar_axle_half(1000,100, 30);