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add ring_hook

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Adrian Mariano 2025-10-23 19:30:39 -04:00
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include<BOSL2/std.scad>
//////////////////////////////////////////////////////////////////////
// LibFile: hooks.scad
// Functions and modules for creating hooks and hook like parts.
// At the moment only one part is supported, a ring hook.
// Includes:
// include <BOSL2/hooks.scad>
// FileGroup: Parts
// FileSummary: Hooks and hook-like parts.
//////////////////////////////////////////////////////////////////////
// Module: ring_hook()
// Synopsis: A hook with a circular hole or attached cylinder
// SynTags: Geom
// Topics: Parts
// See Also: prismoid(), rounded_prism(), ycyl()
// Usage:
// ring_hook(base_size, hole_z, or, od=, [ir=], [hole=], [rounding=], [fillet=], [hole_rounding=], [anchor=], [spin=], [orient=])
// Description:
// Form a part that attaches a loop hook with a cylindrical hole a specified distance away from its mount point.
// You specify a rectangle defining the base a hole diameter or radius, and `hole_z`, a distance from the base to the hole.
// You can set the hole diameter to zero to create a solid paddle with no hole.
// .
// In order to calculate a tangent where the base joins the cylinder,
// the lower corners of the base must be outside the cylinder (see Example 3). This scenario occurs when
// the base is narrower than the Y-cylinder and hole_z is less than Y-cylinder radius. Also, hole_z must
// be large enough to accommodate hole rounding and base rounding.
// Arguments:
// base_size = 2-vector specifying x and y sizes of the base
// hole_z = distance in the z direction from the base to the center of the hole
// or = radius of the cylindrical portion of the part (or zero to create no hole)
// ---
// od = diameter of the cylindrical portion of the part
// ir, id = optional radius/diameter of the center hole
// hole = Set to "circle" for a circle hole, "D" for a D-shaped (semicircular) hole or a path to create a custom hole. Default: "circle"
// rounding = rounding of the vertical-ish edges of the prismoid and the exposed edges of the cylinder
// fillet = base rounding, set negative to form a rounded edge instead of fillet
// hole_rounding = rounding of the optional hole
// anchor = Translate so anchor point is at origin (0,0,0). See [anchor](attachments.scad#subsection-anchor). Default: `CENTER`
// spin = Rotate this many degrees around the Z axis. See [spin](attachments.scad#subsection-spin). Default: `0`
// orient = Vector to rotate top towards. See [orient](attachments.scad#subsection-orient). Default: `UP`
// Named anchors:
// hole_front = front, center of the cylindrical portion of the part (same as the part FRONT if hole_z=or)
// hole_back = back, center of the cylindrical portion of the part (same as the part BACK if hole_z=or)
// tangent_right = right side anchor at the point where the prismoid merges with Y-cylinder, at y=0
// tangent_left = left side anchor at the point where the prismoid merges with Y-cylinder, at y=0
// Attachable Parts:
// "inside" = The inner hole (not defined if there is no hole)
// Example: Ring connector
// ring_hook([50, 10], 25, 25, ir=20);
// Example: Widen the base, add base fillet, no hole
// ring_hook([70, 10], 25, or=25, ir=0, fillet=3, rounding=1.5);
// Example: Narrow base
// ring_hook([40, 10], 25, or=25, ir=0, fillet=3, rounding=1.5);
// Example(3D,VPR=[90,0,0]): If the base is narrower than the cylinder diameter then its corners have to be outside the cylinder for this shape to be defined because it requires a tangent line to the cylinder. This example shows a valid base corner point in blue. An invalid corner point appears in red: no tangent to the circle exists through the red point.
// hole_z = 20;
// base_size = [40, 10];
// outer_radius = 25;
// ring_hook(base_size, hole_z, outer_radius, ir=0);
// up(hole_z) color("blue", 0.25) ycyl(r=outer_radius, h=base_size.y + 2);
// right(0.5*base_size.x) color("blue") ycyl(r=1, h=base_size.y + 2, $fn=12);
// right(0.3*base_size.x) color("red") ycyl(r=1, h=base_size.y + 2, $fn=12);
// Example(3D,VPR=[60.60,0.00,62.10]): Through hole can be specified using or/od, ir/id, wall variables. All of these are equivalent.
// ydistribute(spacing = 25) {
// ring_hook([50, 10], 40, or=25, ir=20);
// ring_hook([50, 10], 40, 25, wall=5);
// ring_hook([50, 10], 40, wall=5, ir=20);
// ring_hook([50, 10], 40, od=50, id=40);
// ring_hook([50, 10], 40, od=50, wall=5);
// ring_hook([50, 10], 40, wall=5, id=40);
// }
// Example: Semi-circular through hole (a D-hole):
// ring_hook([50, 10], 12, 25, ir=15, hole="D", rounding=3, hole_rounding=3, fillet=2);
// Example: hole_z must be greater than 0 with no hole or with hole="D". Here hole_z is 1, close to the minimum value of zero.
// xdistribute(spacing=60){
// ring_hook([50, 10], 1, 25, ir=0);
// ring_hook([50, 10], 1, 25, ir=15, hole="D");
// }
// Example: hole_z must be greater than ir + hole_rounding + fillet when hole="circle". Here hole_z is only 1 larger than the minimum.
// ring_hook([50, 10], hole_z=27, or=25, ir=20, hole_rounding=3, fillet=3);
// Example: Rounding all edges
// ring_hook([50, 10], 40, 25, ir=15, rounding=5, hole_rounding=5, fillet=5);
// Example: Giving an arbitrary path for the hole, in this case an octagon to make the object printable without support.
// ring_hook([50, 20],30, 25, ir=10, hole=octagon(side=10,realign=true), hole_rounding=3, rounding=4) ;
// Example: The ring_hook includes 4 custom anchors: front & back at the center of the cylinder component and left & right at the tangent points.
// ring_hook([55, 10], 12, 25, ir=0) show_anchors(std=false);
// Example: Use the custom anchor to place a screw hole
// include <BOSL2/screws.scad>
// diff()
// ring_hook([20, 10], 15, 7, ir=0, fillet=3)
// attach("hole_front")
// screw_hole("M5", length=20, head="socket", atype="head", anchor=TOP, orient=UP);
// Example: Use the custom anchor to create a cylindrical extension instead of a hole
// $fs=1;$fa=2;
// ring_hook([30,10], hole_z=17, or=10, ir=0, rounding=1.5)
// attach("hole_front", BOT)
// cyl(d=10, h=14, rounding1=-2, rounding2=2);
// Example(3D,VPR=[83.70,0.00,29.20]): Use the "inner" part to create a bar across the hole:
// diff()
// ring_hook([50, 20],30, 25, ir=10, hole_rounding=3, rounding=4)
// attach_part("inner")
// prism_connector( circle(3, $fn=16),
// parent(), LEFT,
// parent(), RIGHT, fillet=1);
module ring_hook(base_size, hole_z, or, ir, od, id, wall, hole="circle",
rounding=0, fillet=0, hole_rounding=0,
anchor=BOTTOM, spin=0, orient=UP) {
or_tmp = get_radius(r=or, d=od);
ir_tmp = get_radius(r=ir, d=id);
dummy = assert(num_defined([ir_tmp, or_tmp, wall])==2, "Must define exactly two of r/d, ir/id and wall");
ir = is_def(ir_tmp) ? ir_tmp : or_tmp - wall;
or = is_def(or_tmp) ? or_tmp : ir + wall;
dummy2 = assert(ir <= or, "Hole doesn't fit or wall size is negative")
assert(sqrt((0.5*base_size.x)^2 + hole_z^2) > or, "Base corners must be outside the cylinder")
assert(in_list(hole,["circle","D"]) || is_path(hole,2), "hole must be \"circle\", \"D\" or a 2d path")
assert(all_nonnegative([hole_rounding]), "hole_rounding must be greater than or equal to 0");
if (ir > 0 && hole=="circle")
assert(ir + hole_rounding < hole_z-fillet,str("ir + hole_rounding must be less than ",hole_z-fillet));
z_offset = (hole_z - or)/2;
tangents = circle_point_tangents(
r=or,
cp=[0,hole_z],
pt=[0.5*base_size.x, 0]);
// we want the tangent with the larger y value
tangent = tangents[0].y > tangents[1].y
? tangents[0] : tangents[1];
// anchor calcs
angle = atan((tangent.x - 0.5*base_size.x)/tangent.y);
top_x = 0.5*base_size.x + (hole_z + or)*tan(angle);
// when or > 0.5*base_size.x, need to move the anchor
// use x^2 + y^2 = r^2, x = sqrt(r^2 - y^2)
delta_y = z_offset;
mid_x = sqrt(or^2 - delta_y^2);
h = hole_z + or;
w = base_size.y;
size = [base_size.x, w];
size2 = [2*top_x, w];
right_tang_dir = unit([tangent.x, 0, tangent.y-hole_z]);
left_tang_dir = unit([-tangent.x,0, tangent.y-hole_z]);
anchors = [
named_anchor("hole_front", [0, -w/2, z_offset], FRONT, 0),
named_anchor("hole_back", [0, w/2, z_offset], BACK, 180),
named_anchor("tangent_right", [tangent[0], 0, tangent[1] - hole_z + z_offset], right_tang_dir, _compute_spin(right_tang_dir,UP,BACK)),
named_anchor("tangent_left", [-tangent[0], 0, tangent[1] - hole_z + z_offset], left_tang_dir, _compute_spin(left_tang_dir,UP,BACK)),
];
override = [
for (i = [-1, 1], j=[-1:1], k=[0:1])
if (k==0 && j!=0 && or > 0.5*base_size.x)
[[i, j, 0],
[mid_x*unit([i, 0, 0]) + 0.5*base_size.y*unit([0, j, 0])]]
else if (k==0 && or > 0.5*base_size.x)
[[i, 0, 0], [mid_x*unit([i, 0, 0])]]
else if (k==1 && j==0)
[[i, 0, 1], [or*sin(45)*unit([i, 0, 0])
+ (z_offset + or*sin(45))*unit([0, 0, k])]]
else if (k==1)
[[i, j, 1], [or*sin(45)*unit([i, 0, 0])
+ 0.5*base_size.y*unit([0, j, 0])
+ (z_offset + or*sin(45))*unit([0, 0, k])]]
];
profile = is_path(hole) ? hole
: hole=="D" ? arc(angle=180, r=ir, rounding=hole_rounding, wedge=true)
: ir > 0 ? circle(ir)
: undef;
parts = is_undef(profile) ? undef
:[
define_part("inner",
attach_geom(
region=[ymove(z_offset,profile)], l=size.y),
T=xrot(90),
inside=true)
];
attachable( anchor, spin, orient,
size=point3d(size,h),
size2=size2,
anchors=anchors,
override=override,
parts=parts
) {
down(h/2)
difference() {
union() {
startangle = atan2(tangent.y-hole_z, tangent.x);
endangle = posmod(atan2(tangent.y-hole_z, -tangent.x),360);
steps = segs(or,endangle-startangle)+1;
delta = (endangle-startangle)/(steps-1);
profile = rounding == 0 ? [[or,0,-base_size.y/2],[or,0,base_size.y/2]]
: let(
// rounded prism roundings are computed on top face, so cos() correction is needed
// to get them to align properly
bez = _smooth_bez_fill([//[or-rounding*(startangle>0?cos(startangle):1),0,-base_size.y/2],
[or-rounding,0,-base_size.y/2],
[or,0,-base_size.y/2],
[or,0,-base_size.y/2+rounding]],0.92),
pts = bezier_curve(bez)
)
concat(pts, reverse(zflip(pts)));
toplist = [
[for(pt=profile) [0,-or,pt.z]],
if (startangle<0)
move(-[tangent.x-base_size.x/2,tangent.y] ,zrot(startangle, profile)),
for(angle = lerpn(startangle, endangle, steps)) zrot(angle, profile),
if (startangle<0)
move(-[-tangent.x+base_size.x/2,tangent.y] ,zrot(endangle, profile)),
];
intersection(){
up(hole_z)xrot(90)
vnf_vertex_array(transpose(toplist),caps=true,col_wrap=true,reverse=true,triangulate=true);
cuboid([max(base_size.x,2*or),w+1, or+hole_z+1],anchor=BOT);
}
// When base is outside the circle the base needs to be clipped so the roundings don't interfere
// This mask does this clipping
maskpath2 = [zrot(startangle,[or+1,0,0]),
zrot(startangle,[or-rounding, 0, 0]),
zrot(startangle+delta, [or-rounding-.1, 0, 0]),
];
maskpath = up(hole_z,xrot(90, [each maskpath2,
[maskpath2[0].x, maskpath2[0].x*tan(startangle+delta),0]
]));
difference(){
rounded_prism(
rect(base_size),
rect( [ 2*tangent.x, w ] ),
h=tangent.y,
joint_bot=-fillet,
joint_sides=rounding,
k_sides=0.92, k_bot=0.92,
anchor=BOT );
if (startangle>0)
xflip_copy()
vnf_vertex_array([fwd(w/2+1, maskpath), back(w/2+1, maskpath)],
col_wrap=true,caps=true,reverse=true);
}
}
if (ir > 0) {
up(hole_z)
prism_connector(
profile,
parent(), FRONT,
parent(), BACK,
fillet=hole_rounding);
}
}
children();
}
}