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Fixed some issues with internal threading.

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Tightening code slightly for generic threaded rod
Added figure showing flank angle
This commit is contained in:
Adrian Mariano 2021-08-28 19:06:47 -04:00
parent 1f7d17eab6
commit c4c9b6cd93
1 changed files with 60 additions and 31 deletions
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91
threading.scad
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@ -916,16 +916,15 @@ module generic_threaded_rod(
rmax = max(_r1,_r2)+pmax; rmax = max(_r1,_r2)+pmax;
depth = pdepth * pitch; depth = pdepth * pitch;
dummy1 = assert(_r1>depth && _r2>depth, "Screw profile deeper than rod radius"); dummy1 = assert(_r1>depth && _r2>depth, "Screw profile deeper than rod radius");
skew_mat = affine3d_skew(sxz=(_r2-_r1)/l); map_threads = right((_r1 + _r2) / 2) // Shift profile out to thread radius
map3d_and_scale = affine3d_frame_map(x=[0,0,1], y=[1,0,0]) // Map profile to 3d, parallel to z axis * affine3d_skew(sxz=(_r2-_r1)/l) // Skew correction for tapered threads
* scale(pitch); // scale profile by pitch * affine3d_frame_map(x=[0,0,1], y=[1,0,0]) // Map profile to 3d, parallel to z axis
* scale(pitch); // scale profile by pitch
hig_table = [ hig_table = [
[-twist, 0], [-twist/2-0.0001, 0],
[-twist/2-0.00001, 0],
[-twist/2+higang1, 1], [-twist/2+higang1, 1],
[+twist/2-higang2, 1], [ twist/2-higang2, 1],
[+twist/2+0.00001, 0], [ twist/2+0.0001, 0],
[+twist, 0],
]; ];
start_steps = sides / starts; start_steps = sides / starts;
thread_verts = [ thread_verts = [
@ -934,10 +933,7 @@ module generic_threaded_rod(
for (step = [0:1:start_steps]) let( for (step = [0:1:start_steps]) let(
ang = 360 * step/sides, ang = 360 * step/sides,
dz = step / start_steps, // z offset for threads at this angle dz = step / start_steps, // z offset for threads at this angle
rot_prof = zrot(ang*dir) // Rotate profile to correct angular location rot_prof = zrot(ang*dir)*map_threads, // Rotate profile to correct angular location
* right((_r1 + _r2) / 2) // Shift profile out to thread radius
* skew_mat // Skew correction for tapered threads
* map3d_and_scale, // Map profile into 3d
full_profile = [ // profile for the entire rod full_profile = [ // profile for the entire rod
for (thread = [-threads/2:1:threads/2-1]) let( for (thread = [-threads/2:1:threads/2-1]) let(
tang = (thread/starts) * 360 + ang, tang = (thread/starts) * 360 + ang,
@ -961,20 +957,21 @@ module generic_threaded_rod(
style = higang1>0 || higang2>0 ? "quincunx" : "min_edge"; style = higang1>0 || higang2>0 ? "quincunx" : "min_edge";
thread_vnfs = vnf_merge([ thread_vnfs = vnf_merge([
// Main thread faces
for (i=[0:1:starts-1]) for (i=[0:1:starts-1])
zrot(i*360/starts, p=vnf_vertex_array(thread_verts, reverse=left_handed, style=style)), zrot(i*360/starts, p=vnf_vertex_array(thread_verts, reverse=left_handed, style=style)),
// Top closing face(s) of thread
for (i=[0:1:starts-1]) let( for (i=[0:1:starts-1]) let(
rmat = zrot(i*360/starts), rmat = zrot(i*360/starts),
pts = deduplicate(list_head(thread_verts[0], len(prof3d)+1)), pts = deduplicate(list_head(thread_verts[0], len(prof3d)+1)),
faces = [for (i=idx(pts,e=-2)) [0, i+1, i]], faces = [for (i=idx(pts,e=-2)) left_handed ? [0, i, i+1] : [0, i+1, i]]
rfaces = left_handed? [for (x=faces) reverse(x)] : faces ) [apply(rmat,pts), faces],
) [apply(rmat,pts), rfaces], // Bottom closing face(s) of thread
for (i=[0:1:starts-1]) let( for (i=[0:1:starts-1]) let(
rmat = zrot(i*360/starts), rmat = zrot(i*360/starts),
pts = deduplicate(list_tail(last(thread_verts), -len(prof3d)-2)), pts = deduplicate(list_tail(last(thread_verts), -len(prof3d)-2)),
faces = [for (i=idx(pts,e=-2)) [len(pts)-1, i, i+1]], faces = [for (i=idx(pts,e=-2)) left_handed ? [len(pts)-1, i+1, i] : [len(pts)-1, i, i+1]]
rfaces = left_handed? [for (x=faces) reverse(x)] : faces ) [apply(rmat,pts), faces]
) [apply(rmat,pts), rfaces]
]); ]);
slope = (_r1-_r2)/l; slope = (_r1-_r2)/l;
@ -986,35 +983,43 @@ module generic_threaded_rod(
// This method is faster but more complex code and it produces green tops // This method is faster but more complex code and it produces green tops
difference() { difference() {
//vnf_validate(vnf_quantize(thread_vnfs), size=0.1); vnf_polyhedron(vnf_quantize(thread_vnfs),convexity=10);
vnf_polyhedron(vnf_quantize(thread_vnfs), convexity=10);
if (!internal){ if (!internal){
if (bevel1 || bevel2) if (bevel1 || bevel2)
rotate_extrude(){ rotate_extrude(){
if (bevel2) polygon([[0,l/2], [_r2+pmax-depth, l/2], [_r2+pmax+slope*depth,l/2-depth], [rmax+1, l/2-depth], [rmax+1,l/2+maxlen], [0,l/2+maxlen]]); if (bevel2) polygon([[ 0, l/2],
if (bevel1) polygon([[0,-l/2], [_r1+pmax-depth, -l/2], [_r1+pmax-slope*depth,-l/2+depth], [rmax+1, -l/2+depth], [rmax+1,-l/2-maxlen], [0,-l/2-maxlen]]); [_r2+pmax-depth, l/2],
[_r2+pmax+slope*depth, l/2-depth],
[ rmax+1, l/2-depth],
[rmax+1, l/2+maxlen],
[ 0, l/2+maxlen]]);
if (bevel1) polygon([[ 0,-l/2],
[_r1+pmax-depth, -l/2],
[_r1+pmax-slope*depth, -l/2+depth],
[ rmax+1, -l/2+depth],
[rmax+1, -l/2-maxlen],
[ 0, -l/2-maxlen]]);
} }
if (!bevel1)
down(l/2) cuboid([2*rmax+1,2*rmax+1, maxlen], anchor=TOP);
if (!bevel2)
up(l/2) cuboid([2*rmax+1,2*rmax+1, maxlen], anchor=BOTTOM);
} }
if (!bevel1 || internal)
down(l/2) cuboid([2*rmax+1,2*rmax+1, maxlen], anchor=TOP);
if (!bevel2 || internal)
up(l/2) cuboid([2*rmax+1,2*rmax+1, maxlen], anchor=BOTTOM);
} }
/* intersection(){ /* intersection(){
//vnf_validate(vnf_quantize(thread_vnfs), size=0.1); //vnf_validate(vnf_quantize(thread_vnfs), size=0.1);
vnf_polyhedron(vnf_quantize(thread_vnfs), convexity=10); vnf_polyhedron(vnf_quantize(thread_vnfs), convexity=10);
cyl(l=l, r1=_r1+pmax, r2=_r2+pmax, chamfer1=bevel1?depth:undef, chamfer2=bevel2?depth:undef); cyl(l=l, r1=_r1+pmax, r2=_r2+pmax, chamfer1=bevel1?depth:undef, chamfer2=bevel2?depth:undef);
}*/ }*/
// Add bevel for internal threads // Add bevel for internal thread mask
if (internal) { if (internal) {
if (bevel1) if (bevel1)
down(l/2)cyl(l=depth, r1=_r1+pmax, r2=_r1+pmax-slope*depth-depth,anchor=BOTTOM); down(l/2+.001)cyl(l=depth, r1=_r1+pmax, r2=_r1+pmax-slope*depth-depth,anchor=BOTTOM);
if (bevel2) if (bevel2)
up(l/2)cyl(l=depth, r2=_r2+pmax, r1=_r2+pmax+slope*depth-depth,anchor=TOP); up(l/2+.001)cyl(l=depth, r2=_r2+pmax, r1=_r2+pmax+slope*depth-depth,anchor=TOP);
} }
} }
children(); children();
@ -1111,7 +1116,7 @@ module generic_threaded_nut(
// subtract any $slop for clearance. // subtract any $slop for clearance.
// . // .
// Higbee specifies tapering applied to the ends of the threads and is given as the linear distance // Higbee specifies tapering applied to the ends of the threads and is given as the linear distance
// over which to taper. // over which to taper. Tapering works on both internal and external threads.
// Arguments: // Arguments:
// d = Inside base diameter of threads. Default: 10 // d = Inside base diameter of threads. Default: 10
// pitch = Distance between threads. Default: 2mm/thread // pitch = Distance between threads. Default: 2mm/thread
@ -1141,6 +1146,30 @@ module generic_threaded_nut(
// [ 6/16, 0 ], // [ 6/16, 0 ],
// ]; // ];
// stroke(profile, width=0.02); // stroke(profile, width=0.02);
// Figure(2D,Med):
// pa_delta = tan(15)/4;
// rr1 = -1/2;
// z1 = 1/4-pa_delta;
// z2 = 1/4+pa_delta;
// profile = [
// [-z2, rr1],
// [-z1, 0],
// [ z1, 0],
// [ z2, rr1],
// ];
// fullprofile = 50*left(1/2,p=concat(profile, right(1, p=profile)));
// stroke(fullprofile,width=1);
// dir = fullprofile[2]-fullprofile[3];
// dir2 = fullprofile[5]-fullprofile[4];
// curve = arc(15,angle=[75,87],r=40 /*67.5*/);
// avgpt = mean([fullprofile[5]+.1*dir2, fullprofile[5]+.4*dir2]);
// color("red"){
// stroke([fullprofile[4]+[0,1], fullprofile[4]+[0,37]], width=1);
// stroke([fullprofile[5]+.1*dir2, fullprofile[5]+.4*dir2], width=1);
// stroke(move(-curve[0]+avgpt,p=curve), width=0.71,endcaps="arrow2");
// right(14)back(19)text("flank",size=4,halign="center");
// right(14)back(14)text("angle",size=4,halign="center");
// }
// Example: // Example:
// thread_helix(d=10, pitch=2, thread_depth=0.75, flank_angle=15, twist=900, $fn=72); // thread_helix(d=10, pitch=2, thread_depth=0.75, flank_angle=15, twist=900, $fn=72);
// thread_helix(d=10, pitch=2, thread_depth=0.75, flank_angle=15, twist=900, higbee=1, $fn=72); // thread_helix(d=10, pitch=2, thread_depth=0.75, flank_angle=15, twist=900, higbee=1, $fn=72);