From 9f9c128b6c8a2e5714d21f64df2a6159bff1ded0 Mon Sep 17 00:00:00 2001 From: Adrian Mariano Date: Mon, 17 Aug 2020 20:44:42 -0400 Subject: [PATCH] Added rabbit clips. --- joiners.scad | 240 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 240 insertions(+) diff --git a/joiners.scad b/joiners.scad index 1ab34e6..1178d4e 100644 --- a/joiners.scad +++ b/joiners.scad @@ -564,6 +564,7 @@ module dovetail(gender, length, l, width, w, height, h, angle, slope, taper, bac } +// Section: Tension Clips // h is total height above 0 of the nub // nub extends below xy plane by distance nub/2 @@ -780,5 +781,244 @@ module snap_pin_socket(size, r, radius, l,length, d,diameter,nub_depth, snap, fi +// Module: rabbit_clip() +// Usage: +// rabbit_clip(type, length, width, snap, thickness, depth, [compression], [clearance], [lock], +// [lock_clearance], [splineteps], [anchor], [orient], [spin]) +// Description: +// Creates a clip with two flexible ears to lock into a mating socket, or create a mask to produce the appropriate +// mating socket. The clip can be made to insert and release easily, or to hold much better, or it can be +// created with locking flanges that will make it very hard or impossible to remove. Unlike the snap pin, this clip +// is rectangular and can be made at any height, so a suitable clip could be very thin. It's also possible to get a +// solid connection with a short pin. +// . +// The type parameters specifies whether to make a clip, a socket mask, or a double clip. The length is the +// total nominal length of the clip. (The actual length will be very close, but not equal to this.) The width +// gives the nominal width of the clip, which is the actual width of the clip at its base. The snap parameter +// gives the depth of the clip sides, which controls how easy the clip is to insert and remove. The clip "ears" are +// made over-wide by the compression value. A nonzero compression helps make the clip secure in its socket. +// The socket's width and length are increased by the clearance value which creates some space and can compensate +// for printing inaccuracy. The socket will be slightly longer than the nominal width. The thickness is the thickness +// curved line that forms the clip. The clip depth is the amount the basic clip shape is extruded. Be sure that you +// make the socket with a larger depth than the clip (try 0.4 mm) to allow ease of insertion of the clip. The clearance +// value does not apply to the depth. The splinesteps parameter increases the sampling of the clip curves. +// . +// By default clips appear with orient=UP and sockets with orient=DOWN. +// . +// The first figure shows the dimensions of the rabbit clip. The second figure shows the clip in red overlayed on +// its socket in yellow. The left clip has a nonzero clearance, so its socket is bigger than the clip all around. +// The right hand locking clip has no clearance, but it has a lock clearance, which provides some space behind +// the lock to allow the clip to fit. (Note that depending on your printer, this can be set to zero.) +// +// Figure(2DMed): +// snap=1.5; +// comp=0.75; +// mid = 8.053; // computed in rabbit_clip +// tip = [-4.58,18.03]; +// translate([9,3]){ +// back_half() +// rabbit_clip("pin",width=12, length=18, depth=1, thickness = 1, compression=comp, snap=snap, orient=BACK); +// color("blue"){ +// stroke([[6,0],[6,18]],width=0.1); +// stroke([[6+comp, 12], [6+comp, 18]], width=.1); +// } +// color("red"){ +// stroke([[6-snap,mid], [6,mid]], endcaps="arrow2",width=0.15); +// translate([6+.4,mid-.15])text("snap",size=1,valign="center"); +// translate([6+comp/2,19.5])text("compression", size=1, halign="center"); +// stroke([[6+comp/2,19.3], [6+comp/2,17.7]], endcap2="arrow2", width=.15); +// fwd(1.1)text("width",size=1,halign="center"); +// xflip_copy()stroke([[2,-.7], [6,-.7]], endcap2="arrow2", width=.15); +// move([-6.7,mid])rot(90)text("length", size=1, halign="center"); +// stroke([[-7,10.3], [-7,18]], width=.15, endcap2="arrow2"); +// stroke([[-7,0], [-7,5.8]], width=.15,endcap1="arrow2"); +// stroke([tip, tip-[0,1]], width=.15); +// move([tip.x+2,19.5])text("thickness", halign="center",size=1); +// stroke([[tip.x+2, 19.3], tip+[.1,.1]], width=.15, endcap2="arrow2"); +// } +// } +// +// Figure(2DMed): +// snap=1.5; +// comp=0; +// translate([29,3]){ +// back_half() +// rabbit_clip("socket", width=12, length=18, depth=1, thickness = 1, compression=comp, snap=snap, orient=BACK,lock=true); +// color("red")back_half() +// rabbit_clip("pin",width=12, length=18, depth=1, thickness = 1, compression=comp, snap=snap, +// orient=BACK,lock=true,lock_clearance=1); +// } +// translate([9,3]){ +// back_half() +// rabbit_clip("socket", clearance=.5,width=12, length=18, depth=1, thickness = 1, +// compression=comp, snap=snap, orient=BACK,lock=false); +// color("red")back_half() +// rabbit_clip("pin",width=12, length=18, depth=1, thickness = 1, compression=comp, snap=snap, +// orient=BACK,lock=false,lock_clearance=1); +// } +// Arguments: +// type = One of "pin", "socket", "male", "female" or "double" to specify what to make. +// length = nominal clip length +// width = nominal clip width +// snap = depth of hollow on the side of the clip +// thickness = thickness of the clip "line" +// depth = amount to extrude clip (give extra room for the socket, about 0.4mm) +// compression = excess width at the "ears" to lock more tightly. Default: 0.1 +// clearance = extra space in the socket for easier insertion. Default: 0.1 +// lock = set to true to make a locking clip that may be irreversible. Default: false +// lock_clearance = give clearance for the lock. Default: 0 +// splinesteps = number of samples in the curves of the clip. Default: 8 +// anchor = anchor point for clip +// orient = clip orientation. Default: UP for pins, DOWN for sockets +// spin = spin the clip. Default: 0 +// +// Example: Here are several sizes that work printed in PLA on a Prusa MK3, with default clearance of 0.1 and a depth of 5 +// module test_pair(length, width, snap, thickness, compression, lock=false) +// { +// depth = 5; +// extra_depth = 10;// Change this to 0.4 for closed sockets +// cuboid([max(width+5,12),12, depth], chamfer=.5, edges=[FRONT,"Y"], anchor=BOTTOM) +// attach(BACK) +// rabbit_clip(type="pin",length=length, width=width,snap=snap,thickness=thickness,depth=depth, +// compression=compression,lock=lock); +// right(width+13) +// diff("remove") +// cuboid([width+8,max(12,length+2),depth+3], chamfer=.5, edges=[FRONT,"Y"], anchor=BOTTOM) +// attach(BACK) +// rabbit_clip(type="socket",length=length, width=width,snap=snap,thickness=thickness,depth=depth+extra_depth, +// lock=lock,compression=0,$tags="remove"); +// } +// left(37)ydistribute(spacing=28){ +// test_pair(length=6, width=7, snap=0.25, thickness=0.8, compression=0.1); +// test_pair(length=3.5, width=7, snap=0.1, thickness=0.8, compression=0.1); // snap = 0.2 gives a firmer connection +// test_pair(length=3.5, width=5, snap=0.1, thickness=0.8, compression=0.1); // hard to take apart +// } +// right(17)ydistribute(spacing=28){ +// test_pair(length=12, width=10, snap=1, thickness=1.2, compression=0.2); +// test_pair(length=8, width=7, snap=0.75, thickness=0.8, compression=0.2, lock=true); // With lock, very firm and irreversible +// test_pair(length=8, width=7, snap=0.75, thickness=0.8, compression=0.2, lock=true); // With lock, very firm and irreversible +// } +// Example: Double clip to connect two sockets +// rabbit_clip("double",length=8, width=7, snap=0.75, thickness=0.8, compression=0.2,depth=5); +// Example: A modified version of the clip that acts like a backpack strap clip, where it locks tightly but you can squeeze to release. +// cuboid([25,15,5],anchor=BOTTOM) +// attach(BACK)rabbit_clip("pin", length=25, width=25, thickness=1.5, snap=2, compression=0, lock=true, depth=5, lock_clearance=3); +// left(32) +// diff("remove") +// cuboid([30,30,11],orient=BACK,anchor=BACK){ +// attach(BACK)rabbit_clip("socket", length=25, width=25, thickness=1.5, snap=2, compression=0, lock=true, depth=5.5, lock_clearance=3,$tags="remove"); +// xflip_copy() +// position(FRONT+LEFT) +// xscale(0.8) +// zcyl(l=20,r=13.5, $tags="remove",$fn=64); +// } +module rabbit_clip(type, length, width, snap, thickness, depth, compression=0.1, clearance=.1, lock=false, lock_clearance=0, + splinesteps=8, anchor, orient, spin=0) +{ + assert(is_num(width) && width>0,"Width must be a positive value"); + assert(is_num(length) && length>0, "Length must be a positive value"); + assert(is_num(thickness) && thickness>0, "Thickness must be a positive value"); + assert(is_num(snap) && snap>=0, "Snap must be a non-negative value"); + assert(is_num(depth) && depth>0, "Depth must be a positive value"); + assert(is_num(compression) && compression >= 0, "Compression must be a nonnegative value"); + assert(is_bool(lock)); + assert(is_num(lock_clearance)); + legal_types = ["pin","socket","male","female","double"]; + assert(in_list(type,legal_types),str("type must be one of ",legal_types)); + + if (type=="double") { + attachable(size=[width+2*compression, depth, 2*length], anchor=default(anchor,BACK), spin=spin, orient=default(orient,BACK)){ + union(){ + rabbit_clip("pin", length=length, width=width, snap=snap, thickness=thickness, depth=depth, compression=compression, + lock=lock, anchor=BOTTOM, orient=UP); + rabbit_clip("pin", length=length, width=width, snap=snap, thickness=thickness, depth=depth, compression=compression, + lock=lock, anchor=BOTTOM, orient=DOWN); + cuboid([width-thickness, depth, thickness]); + } + children(); + } + } else { + anchor = default(anchor,BOTTOM); + is_pin = in_list(type,["pin","male"]); + default_overlap = 0.01 * (is_pin?1:-1); // Shift by this much to undo default overlap + extra = 0.02; // Amount of extension below nominal based position for the socket, must exceed default overlap of 0.01 + clearance = is_pin ? 0 : clearance; + compression = is_pin ? compression : 0; + orient = is_def(orient) ? orient + : is_pin ? UP + : DOWN; + earwidth = 2*thickness+snap; + point_length = earwidth/2.15; + // The adjustment is using cos(theta)*earwidth/2 and sin(theta)*point_length, but the computation + // is obscured because theta is atan(length/2/snap) + scaled_len = length - 0.5 * (earwidth * snap + point_length * length) / sqrt(sqr(snap)+sqr(length/2)); + bottom_pt = [0,max(scaled_len*0.15+thickness, 2*thickness)]; + ctr = [width/2,scaled_len] + line_normal([width/2-snap, scaled_len/2], [width/2, scaled_len]) * earwidth/2; + inside_pt = circle_circle_tangents(bottom_pt, 0, ctr, earwidth/2)[0][1]; + sidepath =[ + [width/2,0], + [width/2-snap,scaled_len/2], + [width/2+(is_pin?compression:0), scaled_len], + ctr - point_length * line_normal([width/2,scaled_len], inside_pt), + inside_pt + ]; + fullpath = concat( + sidepath, + [bottom_pt], + reverse(apply(xflip(),sidepath)) + ); + assert(fullpath[4].y < fullpath[3].y, "Pin is too wide for its length"); + + snapmargin = -snap + select(sidepath,-1).x;// - compression; + if (is_pin){ + if (snapmargin<0) echo("WARNING: The snap is too large for the clip to squeeze to fit its socket") + echo(snapmargin=snapmargin); + } + // Force tangent to be vertical at the outer edge of the clip to avoid overshoot + fulltangent = list_set(path_tangents(fullpath, uniform=false),[2,8], [[0,1],[0,-1]]); + + subset = is_pin ? [0:10] : [0,1,2,3, 7,8,9,10]; // Remove internal points from the socket + tangent = select(fulltangent, subset); + path = select(fullpath, subset); + + socket_smooth = .04; + pin_smooth = [.075, .075, .15, .12, .06]; + smoothing = is_pin + ? concat(pin_smooth, reverse(pin_smooth)) + : let(side_smooth=select(pin_smooth, 0, 2)) + concat(side_smooth, [socket_smooth], reverse(side_smooth)); + bez = path_to_bezier(path,relsize=smoothing,tangents=tangent); + rounded = bezier_polyline(bez,splinesteps=splinesteps); + bounds = pointlist_bounds(rounded); + kk = search([bounds[1].y], subindex(rounded,1)); + echo(rounded[kk[0]]); + extrapt = is_pin ? [] : [rounded[0] - [0,extra]]; + finalpath = is_pin ? rounded + : let(withclearance=offset(rounded, r=-clearance)) + concat( [[withclearance[0].x,-extra]], + withclearance, + [[-withclearance[0].x,-extra]]); + attachable(size=[bounds[1].x-bounds[0].x, depth, bounds[1].y-bounds[0].y], anchor=anchor, spin=spin, orient=orient){ + xrot(90) + translate([0,-(bounds[1].y-bounds[0].y)/2+default_overlap,-depth/2]) + linear_extrude(height=depth, convexity=10) { + if (lock) + xflip_copy() + right(clearance) + polygon([sidepath[1]+[-thickness/10,lock_clearance], + sidepath[2], + [sidepath[2].x,sidepath[1].y+lock_clearance]]); + if (is_pin) + offset_stroke(finalpath, width=[thickness,0]); + else + polygon(finalpath); + } + children(); + } + } +} + + + // vim: expandtab tabstop=4 shiftwidth=4 softtabstop=4 nowrap