From 35376827d163eda8b03079e6d2b7432a3ddcef93 Mon Sep 17 00:00:00 2001 From: Simon Brooke Date: Wed, 24 Sep 2025 12:07:28 +0100 Subject: [PATCH] Moved the lower knuckle out into its own file, and substantially improved it. I'm still having problems with fudge factors which I need to resolve; I need to learn more about filletting, rounding, radiusing and fairing. --- model/fourbar.scad | 80 ++++------------------ model/lowerknuckle.scad | 144 ++++++++++++++++++++++++++++++++++++++++ model/tricycle.scad | 2 +- 3 files changed, 157 insertions(+), 69 deletions(-) create mode 100644 model/lowerknuckle.scad diff --git a/model/fourbar.scad b/model/fourbar.scad index 77966db..3f07b39 100644 --- a/model/fourbar.scad +++ b/model/fourbar.scad @@ -5,6 +5,7 @@ include include include +include include $fn=64; @@ -48,64 +49,6 @@ module fourbar_leg(length=1000, chord=100, lat_skew=35, long_skew=30) { } -module lower_bar_end_knuckle(chord=100, pivot_radius=12, rise=8,lat_skew=30) { - l_body=chord * 1.5; - w_body=pivot_radius * 2.5; - h_axis=pivot_radius * 2.75; - - difference() { - union () { - translate([l_body/2, w_body/2, h_axis]) - rotate([0, 90, 0]) - cyl(h=l_body, r=w_body/2, rounding=5); - - // 'except=TOP' in phrase introduces the spurious hulls - translate([l_body/2, w_body/2, h_axis*.75]) - cuboid([l_body, w_body, h_axis * .75], rounding=5); - // bulge for wheel axle; the fork insertion end of - // a lefty axle is 25mm diameter - translate([chord * 0.25, w_body/2, 0]) - rotate([90, 0, 0]) - cyl(h=w_body, r=25, rounding=5); - // fairing for this - translate([chord * 0.25, w_body/2, -3]) - rotate([80, 0, 90]) - prismoid([w_body, 45], [w_body, 10], rounding=5, h=l_body * .75); - - } - translate([ chord*0.25, -1, pivot_radius * 3]) - cube([chord, pivot_radius * 4, pivot_radius * 4]); - // scoop for leg-bottom knuckle to rotate within - translate([ chord*0.25, w_body/2, h_axis]) - rotate([0, 90, 0]) - cylinder(h=chord, r=pivot_radius * 1.3); - // through hole for pivot axle - translate([-1, w_body/2, h_axis]) - rotate([0, 90, 0]) - cylinder(h=l_body+2, r=pivot_radius/3); - // through hole for wheel axle - translate([ chord * 0.25, w_body +1, 0]) - rotate([90, 0, 0]) - cylinder(h=w_body-5, r=12.5); - } - - // airfoil stub to be epoxied into the lower bar of - // the linkage - translate([chord*1.25, 1, 30]) - rotate([90 + rise, 360 - lat_skew, 0]) - airfoil(h=chord, L=2 - chord); - -// // brake disk -// translate([(0 - (chord*1.25)), (l_hlb * cos(rise)), 1]) -// rotate([90, 0, 0]) -// color("silver") -// cylinder( h=1.5, r=75); -// // wheel (obviously) -// translate([(0 - (chord*1.25)), (l_hlb * cos(rise)), -10]) -// wheel(); - -} - module fourbar_axle_half( length=1000, chord=100, lat_skew=35, long_skew=30, shoulder=650) { rise=8; @@ -127,6 +70,16 @@ module fourbar_axle_half( length=1000, chord=100, lat_skew=35, long_skew=30, sho rotate([0, long_skew, 0]) translate([(0 - (chord*1.25)), (l_hlb * cos(rise) + 72), -62]) lower_bar_end_knuckle(chord, 12, rise, lat_skew); + + rotate([0, long_skew, 0]) + translate([(0 - (chord*1.25)), (l_hlb * cos(rise) + 155), -62]) + wheel(); + rotate([0, long_skew, 0]) + translate([(0 - (chord*1.25)), (l_hlb * cos(rise) + 115), -62]) + rotate([90, 0, 0]) + color("silver") + cylinder( h=1.5, r=75); + } @@ -145,15 +98,6 @@ module fourbar(length=1000, chord=100, lat_skew=30, long_skew=30, shoulder=650) fourbar_axle_half(length, chord, lat_skew, long_skew, shoulder); } -translate([-125, 0, 0]) - color("blue") - lower_bar_end_knuckle(); -translate([-100, 74, 0]) - wheel(); -translate([-100, 34, 0]) - color("silver") - rotate([90, 0, 0]) - cylinder(h=1.5, r=75); // fourbar(length=1000, chord=100, long_skew=30, lat_skew=35, shoulder=650); -// fourbar_axle_half(1000,100, 30); \ No newline at end of file +// fourbar_axle_half(); \ No newline at end of file diff --git a/model/lowerknuckle.scad b/model/lowerknuckle.scad new file mode 100644 index 0000000..4377230 --- /dev/null +++ b/model/lowerknuckle.scad @@ -0,0 +1,144 @@ +// lowerknuckle.scad + +// (c) Simon Brooke 2025; CC-BY-SA + +include +include +include +include + +$fn=64; + + +module lower_bar_end_knuckle_old(chord=100, pivot_radius=12, rise=8,lat_skew=30) { + l_body=chord * 1.5; + w_body=pivot_radius * 2.5; + h_axis=pivot_radius * 2.75; + + difference() { + union () { + translate([l_body/2, w_body/2, h_axis]) + rotate([0, 90, 0]) + cyl(h=l_body, r=w_body/2, rounding=5); + + // 'except=TOP' in phrase introduces the spurious hulls + translate([l_body/2, w_body/2, h_axis*.75]) + cuboid([l_body, w_body, h_axis * .75], rounding=5); + // bulge for wheel axle; the fork insertion end of + // a lefty axle is 25mm diameter + translate([chord * 0.25, w_body/2, 0]) + rotate([90, 0, 0]) + cyl(h=w_body, r=25, rounding=5); + // fairing for this + translate([chord * 0.25, w_body/2, -3]) + rotate([80, 0, 90]) + prismoid([w_body, 45], [w_body, 10], rounding=5, h=l_body * .75); + + } + translate([ chord*0.25, -1, pivot_radius * 3]) + cube([chord, pivot_radius * 4, pivot_radius * 4]); + // scoop for leg-bottom knuckle to rotate within + translate([ chord*0.25, w_body/2, h_axis]) + rotate([0, 90, 0]) + cylinder(h=chord, r=pivot_radius * 1.3); + // through hole for pivot axle + translate([-1, w_body/2, h_axis]) + rotate([0, 90, 0]) + cylinder(h=l_body+2, r=pivot_radius/3); + // through hole for wheel axle + translate([ chord * 0.25, w_body +1, 0]) + rotate([90, 0, 0]) + cylinder(h=w_body-5, r=12.5); + } + + // airfoil stub to be epoxied into the lower bar of + // the linkage + translate([chord*1.25, 1, 30]) + rotate([90 + rise, 360 - lat_skew, 0]) + airfoil(h=chord, L=2 - chord); + +// // brake disk +// translate([(0 - (chord*1.25)), (l_hlb * cos(rise)), 1]) +// rotate([90, 0, 0]) +// color("silver") +// cylinder( h=1.5, r=75); +// // wheel (obviously) +// translate([(0 - (chord*1.25)), (l_hlb * cos(rise)), -10]) +// wheel(); + +} + +module lower_bar_end_knuckle(chord=100, pivot_radius=12, rise=8,lat_skew=30, colour="blue") { + l_body=chord * 2; + w_body=pivot_radius * 2.5; + h_axis=pivot_radius * 2.75; + + difference() { + union () { + // (more streamlined) body + translate([160, w_body/2, -22]) + rotate([0,0,180]) + scale([1, 2, 1]) + color( colour) + airfoil(h=70, L=l_body); + // boss for wheel axle + translate([ chord * 0.25, w_body * 0.9, 0]) + rotate([90, 0, 0]) + color( colour) + cyl(h=w_body * 1.25, r=20, rounding=5); + + } + // scoop for leg-bottom knuckle to rotate within + translate([ chord*0.25, w_body/2, h_axis]) + rotate([0, 90, 0]) + cylinder(h=chord, r=pivot_radius * 1.3); + // space for the airfoil leg to emerge + translate([ chord*0.25, w_body*.75, pivot_radius * 2.25]) + rotate([lat_skew + 45, 0, 0]) + cube([chord, pivot_radius * 4, pivot_radius * 4]); + // through hole for pivot axle + translate([-1, w_body/2, h_axis]) + rotate([0, 90, 0]) + cylinder(h=250, r=pivot_radius/3); + // through hole for wheel axle + translate([ chord * 0.25, w_body *1.5, 0]) + rotate([90, 0, 0]) + cylinder(h=w_body * 1.4, r=12.5); + // slice off the front bottom + translate([chord * 1.25, w_body/2, 0 - w_body]) + rotate([270-lat_skew, 0, 90]) + color( colour) + cuboid([2* w_body, 2*w_body, l_body *.75]); + // slice off the upper back + translate([0, w_body/2, w_body * 2.5]) + rotate([270-lat_skew, 0, 90]) + color( colour) + cuboid([2* w_body, 2*w_body, l_body *.75]); + } + + // airfoil stub to be epoxied into the lower bar of + // the linkage + translate([chord*1.25, 1, 30]) + rotate([90 + rise, 360 - lat_skew, 0]) + color( colour) + airfoil(h=chord, L=2 - chord); + +// // brake disk +// translate([(0 - (chord*1.25)), (l_hlb * cos(rise)), 1]) +// rotate([90, 0, 0]) +// color("silver") +// cylinder( h=1.5, r=75); +// // wheel (obviously) +// translate([(0 - (chord*1.25)), (l_hlb * cos(rise)), -10]) +// wheel(); + +} + +//translate([-125, 0, 0]) +// lower_bar_end_knuckle(); +//translate([-125, 0, 125]) +// color("blue") +// lower_bar_end_knuckle(); +//translate([-100, 74, 0]) +// wheel(); + diff --git a/model/tricycle.scad b/model/tricycle.scad index 6548999..3874f72 100644 --- a/model/tricycle.scad +++ b/model/tricycle.scad @@ -11,7 +11,7 @@ include rotate([0, 0, 270]) translate([0, 1300, 180]) subframe(structure="carbon"); -translate([0, 0, 320]) +translate([0, 0, 250]) fourbar(length=1000, chord=100, long_skew=30, lat_skew=35, shoulder=650); translate([800, 0, 120])