Update for v4.0

README.md

@@ -1,10 +1,35 @@
-# flag-clip
+# Flag Clip (Revised)
 
-Hybrid clip / carabiner 3D printable model to attach flags to the rope of a flag pole.
+Hybrid clip / carabiner 3D printable model to attach flags to the cable of a flag pole.
 
 The gate of the carabiner does double duty as the lever of the clip.
 
+Spring mechanism inspired by [https://www.thingiverse.com/thing:1212828/remixes](https://www.thingiverse.com/thing:1212828/remixes)
+
 Since this was intended for outdoors use, I've printed this in PETG.
 
 ![](img/clip.jpeg)
-![](img/flag.jpeg)
+
+OpenSCAD file enclosed for tuning. In particular, the diameter of the eye at the bottom needs to be closely matched to the flag cable diameter.
+
+# Installation
+
+![](img/install_1.jpeg)
+![](img/install_2.jpeg)
+![](img/install_3.jpeg)
+![](img/install_4.jpeg)
+![](img/install_5.jpeg)
+
+## Revision History
+
+### 2022-05-15 Version 1.0	
+
+Initial Design
+
+### 2022-07-04 Version 2.0
+
+Substantial Revision. It turns out that even a moderate wind was enough to pull the flag off the pole with the initial design. This revision is considerably more robust to wind, though it still failed in a heavy thunderstorm.
+
+### 2023-08-15 Version 4.0
+
+Revised again (Rev v3 was unsuccessful). This time tested through an entire season's worth of storms.

flagclip.scad

@@ -0,0 +1,173 @@
+/*
+ * Flagclip - Flag attachment carabine
+ *
+ * Copyright (C) 2022-23 Matthias Neeracher <microtherion@gmail.com>
+ */
+
+$fn= $preview ? 32 : 64;
+
+// Diameter of flagpole wire
+wire_dia        = 3.9;          // [1.0:0.05:7.0]
+
+/* [Other Parameters - Tune if Needed] */
+// Thickness (Z)
+thickness       = 4.0;          // [3.0:0.25:8.0]
+// Width of outer walls
+wall            = 4.0;          // [2.0:0.25:6.0]
+// Gaps for carabine and spring openings
+gap             = 1.0;          // [0.5:0.25:2.0]
+
+/* [Spring Parameters - Tune if Needed] */
+// Spring Center Radius
+spring_center   = 3.0;          // [2.0:0.5:10.0]
+// Gap Between Inner and Outer Rings
+spring_gap      = 3.0;          // [1.0:0.5:5.0]
+
+/* [Carabine Parameters - Tune if Needed] */
+// Aperture Angle of Carabine Loop
+cara_aperture   = 45.0;         // [30:5:90]
+// Length of Carabine Arm
+cara_arm        = 15.0;         // [10:5:50]
+
+/* [Clip Parameters - Tune if Needed] */
+// Width of Inner Gap for Clip
+clip_aper       = 2.5;          // [1.0:.5:10]
+// Width of Clip at Bottom of Opening
+clip_base       = 12.0;         // [10.0:50.0]
+// Length of Clip Arm
+clip_arm        = 18.0;         // [15.0:50.0]
+// Arc of Wire Holder
+clip_arc        = 290;          // [190.0:10:330]
+// Width of Wire Holder Walls
+clip_wall       = 2.0;          // [1.0:0.25:4.0]
+// Clearance of Gap from Edge of Spring
+clip_clear      = 4.0;          // [1.0:1.0:10.0]
+// Vertical Displacement of Clip Gap
+clip_lever      = 4.0;          // [0.0:0.25:6.0]
+
+function intersect_circle(p0, v, r) =
+    let (num = sqrt((r^2-p0[0]^2)*v[1]^2+2*p0[0]*p0[1]*v[0]*v[1]+(r^2-p0[1]^2)*v[0]^2)-p0[1]*v[1]-p0[0]*v[0],
+         l = num/(v[1]^2+v[0]^2)) p0+l*v;
+
+function intersect_lines(p0, v, q0, w) =
+    let (l = (-q0[0]*w[1]+p0[0]*w[1]+(q0[1]-p0[1])*w[0])/(v[1]*w[0]-v[0]*w[1])) p0+l*v;
+
+module flagclip(wire_dia=wire_dia, thickness=thickness, wall=wall,
+                spring_center=spring_center, spring_gap=spring_gap,
+                cara_aperture=cara_aperture, cara_arm=cara_arm,
+                gap=gap,
+                clip_aper=clip_aper, clip_base=clip_base, clip_arm=clip_arm,
+                clip_arc=clip_arc, clip_wall=clip_wall, clip_clear=clip_clear,
+                clip_lever=clip_lever)
+{
+    spring_inner_in_r  = spring_center;
+    spring_inner_out_r = spring_inner_in_r + wall;
+    spring_outer_in_r  = spring_inner_out_r + spring_gap;
+    spring_outer_out_r = spring_outer_in_r + wall;
+
+    cara_ratio_r       = [sin(0.5*cara_aperture), cos(0.5*cara_aperture)];
+    cara_ratio_out_r   = [cos(0.5*cara_aperture), -sin(0.5*cara_aperture)];
+    cara_inner_bot_r   = [0.5*spring_gap, spring_outer_in_r*cos(asin(0.5*spring_gap/spring_outer_in_r))];
+    cara_inner_top_r   = cara_inner_bot_r+cara_arm*cara_ratio_r;
+    cara_outer_top_r   = cara_inner_top_r+wall*cara_ratio_out_r;
+    cara_outer_top_rp  = cara_inner_top_r+(wall+1)*cara_ratio_out_r;
+    cara_outer_bot_r   = cara_outer_top_r-(cara_arm-0.5*wall)*cara_ratio_r;
+    cara_ratio_l       = [-sin(0.5*cara_aperture), cos(0.5*cara_aperture)];
+    cara_ratio_out_l   = [-cos(0.5*cara_aperture), -sin(0.5*cara_aperture)];
+    cara_inner_bot_l   = [-cara_inner_bot_r[0], cara_inner_bot_r[1]];
+    cara_inner_top_l   = cara_inner_bot_l+cara_arm*cara_ratio_l;
+    cara_outer_top_l   = cara_inner_top_l+wall*cara_ratio_out_l;
+    cara_outer_top_lp  = cara_inner_top_l+(wall+1)*cara_ratio_out_l;
+    cara_outer_bot_l   = cara_outer_top_l-(cara_arm-0.5*wall)*cara_ratio_l;
+    cara_inner_gap_l   = cara_inner_bot_l+(cara_arm-gap)*cara_ratio_l;
+    cara_outer_gap_l   = cara_inner_gap_l+wall*cara_ratio_out_l;
+    cara_loop_center   = [0,cara_inner_top_r[1]];
+    cara_loop_in_r     = cara_inner_top_r[0];
+    cara_loop_out_r    = cara_loop_in_r+wall;
+
+    clip_half_aperture = asin(0.5*(clip_base-clip_aper)/clip_arm);
+    clip_ratio_r       = [sin(clip_half_aperture), -cos(clip_half_aperture)];
+    clip_ratio_out_r   = [-clip_ratio_r[1], clip_ratio_r[0]];
+    clip_inner_in_r    = [0.5*clip_aper, -spring_inner_in_r*cos(asin(0.5*clip_aper/spring_inner_in_r))];
+    clip_inner_in_l    = [-clip_inner_in_r[0], clip_inner_in_r[1]];
+    clip_inner_out_r   = [0.5*clip_aper, -spring_inner_out_r*cos(asin(0.5*clip_aper/spring_inner_out_r))];
+    clip_inner_out_l   = [-clip_inner_out_r[0], clip_inner_out_r[1]];
+    clip_bot_in_r      = clip_inner_out_r+clip_arm*clip_ratio_r;
+    clip_bot_out_r     = clip_bot_in_r+wall*clip_ratio_out_r;
+    clip_inner_r       = clip_bot_out_r-(clip_arm+0.5*wall)*clip_ratio_r;
+    clip_inner_inter_r = intersect_circle(clip_inner_r, clip_ratio_r, spring_inner_out_r);
+    clip_ratio_l       = [-clip_ratio_r[0], clip_ratio_r[1]];
+    clip_ratio_out_l   = [clip_ratio_l[1], -clip_ratio_l[0]];
+    clip_bot_in_l      = clip_inner_out_l+clip_arm*clip_ratio_l;
+    clip_bot_out_l     = clip_bot_in_l+wall*clip_ratio_out_l;
+    clip_inner_l       = clip_bot_out_l-(clip_arm+0.5*wall)*clip_ratio_l;
+    clip_outer_inter_l = intersect_circle(clip_inner_l, clip_ratio_l, spring_outer_out_r);
+    clip_inner_inter_l = intersect_circle(clip_inner_l, clip_ratio_l, spring_inner_out_r);
+    clip_outer_gap_t   = clip_outer_inter_l+clip_clear*clip_ratio_l;
+    clip_outer_gap_b   = clip_outer_gap_t+gap*clip_ratio_l;
+    clip_inner_gap_t   = clip_outer_gap_t-wall*clip_ratio_out_l-clip_lever*clip_ratio_l;
+    clip_inner_gap_b   = clip_inner_gap_t+gap*clip_ratio_l;
+    wire_center        = [0, clip_bot_in_r[1]+0.5*wire_dia];
+    clip_angle         = 180-0.5*clip_arc;
+    wire_ratio         = [sin(clip_angle), cos(clip_angle)];
+    wire_out_r         = clip_wall*[wire_ratio[1], -wire_ratio[0]];
+    clip_wire_inter_r  = intersect_lines(clip_bot_in_r, clip_ratio_r, wire_center, wire_ratio);
+    clip_wire_inter_l  = [-clip_wire_inter_r[0], clip_wire_inter_r[1]];
+    wire_out_l         = clip_wall*[-wire_ratio[1], -wire_ratio[0]];
+
+    linear_extrude(height=thickness) {
+        /* Spring */
+        difference() {
+            union() {
+                difference() {
+                    circle(r = spring_outer_out_r);
+                    circle(r = spring_outer_in_r);
+                }
+                circle(r = spring_inner_out_r);
+                translate([-spring_outer_in_r-1,-0.5*wall,0])
+                    square(size=[2*spring_outer_in_r+2, wall]);
+            }
+            circle(r = spring_inner_in_r);
+            /* Opening for Carabine */
+            polygon(points=[cara_inner_bot_r, cara_inner_top_r, cara_inner_top_l, cara_inner_bot_l]);
+            /* Opening for Clip */
+            polygon(points=[clip_inner_in_l, clip_inner_out_l, clip_bot_in_l, clip_bot_in_r, clip_inner_out_r, clip_inner_in_r]);
+            polygon(points=[clip_inner_gap_b, clip_inner_gap_t, clip_outer_gap_t, clip_outer_gap_b]);
+        }
+        /* Carabine */
+        difference() {
+            translate(cara_loop_center) circle(r = cara_loop_out_r);
+            translate(cara_loop_center) circle(r = cara_loop_in_r);
+            polygon(points=[cara_outer_top_rp, cara_inner_top_r, cara_loop_center, cara_inner_top_l, cara_outer_top_lp, [cara_outer_top_l[0], 0], [cara_outer_top_r[0], 0]]);
+        }
+        polygon(points=[cara_outer_bot_r, cara_outer_top_r, cara_inner_top_r, cara_inner_bot_r]);
+        polygon(points=[cara_outer_bot_l, cara_outer_gap_l, cara_inner_gap_l, cara_inner_bot_l]);
+        /* Clip */
+        difference() {
+            translate(clip_bot_in_r) circle(r=wall);
+            translate([clip_bot_in_r[0]-wall, clip_bot_in_r[1]-wall]) square(size=[wall, 2*wall]);
+        }
+        polygon(points=[clip_bot_in_r, clip_bot_out_r, clip_inner_inter_r, clip_inner_out_r]);
+        difference() {
+            translate(clip_bot_in_l) circle(r=wall);
+            translate([clip_bot_in_l[0], clip_bot_in_r[1]-wall]) square(size=[wall, 2*wall]);
+        }
+        difference() {
+            polygon(points=[clip_bot_in_l, clip_inner_out_l, clip_inner_inter_l, clip_bot_out_l]);
+            polygon(points=[clip_inner_gap_b, clip_inner_gap_t, clip_outer_gap_t, clip_outer_gap_b]);
+        }
+        translate([clip_bot_in_l[0], clip_bot_in_l[1]-wall]) square(size=[clip_base, wall]);
+        difference() {
+            union() {
+                translate(wire_center) circle(r=0.5*wire_dia+clip_wall);
+                polygon(points=[wire_center, wire_center+wire_out_r, clip_wire_inter_r+wire_out_r, clip_wire_inter_r]);
+                polygon(points=[wire_center, clip_wire_inter_l, clip_wire_inter_l+wire_out_l, wire_center+wire_out_l]);
+            }
+            translate(wire_center) circle(r=0.5*wire_dia);
+            polygon(points=[wire_center, clip_wire_inter_r, clip_wire_inter_l]);
+            translate(clip_wire_inter_l) square([clip_base, wall]);
+        }
+    }
+}
+
+flagclip();