// ============================================================ // T123 - Kirby handle-spring winder ("T-123" torque spanner) // A T-handle tool, basically a tree of interconnected cylinders: // a top HUB carrying the crossbar (tommy bar), a STEM down to a // DISC, and a dark TANG dowel that engages the slot in the handle- // spring shaft to wind it against spring force. // Built from standard rod + dowel-pin stock, friction-fit; each // joint secured with Loctite 243 (blue, medium strength, and // OIL-TOLERANT - the tool carries an oil film and the handle areas // it works in usually have a little oil; 243 = 242 + oil resistance). // No casting or welding: reproducible at home with a lathe + saw. // Units: millimeters. // ============================================================ // Part View // "3D" -> assembled colored tool (export STL / 3MF) // Each major part on its own, top-to-bottom: "Bars", "Hub", "Disc", "Dowel" view = "3D"; // ["3D", "Bars", "Hub", "Disc", "Dowel"] // - rods - rod_dia = 8.0; // diameter of the rod stock (stem + crossbar) stem_len = 89.0; // length of the vertical stem (83 exposed + 6 pressed into the hub) cross_len = 102.0; // length of the crossbar (tommy bar) // - top hub (both bars press into this - they don't touch each other) - hub_dia = 19.0; // hub cylinder diameter stem_insert = 6.0; // how far the stem presses up into the hub bottom (deeper = stronger) hub_pad = 3.0; // solid gap below the crossbar (stem top -> cross hole) hub_pad_top = 2.0; // solid gap above the crossbar (cross hole -> hub top) hub_len = stem_insert + hub_pad + rod_dia + hub_pad_top; // hub height = 19 (6 + 3 + 8 + 2) hub_bottom = stem_len - stem_insert; // hub bottom Z (= 83) cross_z = hub_bottom + stem_insert + hub_pad + rod_dia / 2; // crossbar axis Z (= 96) // - disc near the bottom end - disc_dia = 25.0; // disc diameter disc_thick = 6.0; // disc thickness (height, Z) disc_z = 6.0; // bare stem below the disc (disc bottom sits this far up from the stem's bottom end) // - tang dowel (the critical tab; a dowel pin pressed THROUGH the disc) - // Pressed the full disc depth for shear support: this one pin carries the entire // spring-winding load (~30+ lb of twist), so deep embedment resists shearing it off. // TIP: the dowel end has a 0.1mm lead-in chamfer (leaving 3mm of full-dia usable // length); still knock any burr off the tip with 400-600 grit sandpaper. dowel_dia = 3.0; // dowel diameter (grabs the handle-fork shaft slot - must be exact) dowel_len = 9.0; // dowel length (9mm dowel pin - runs the full disc height + proud) dowel_proud = 3.1; // how far it sticks out below the disc bottom (precise to 0.1mm) dowel_margin = 1.0; // gap from the disc's edge in to the dowel dowel_r = disc_dia / 2 - dowel_margin - dowel_dia / 2; // dowel centre radius (= 10) dowel_recess = disc_thick - (dowel_len - dowel_proud); // dowel top sits this far below the disc top face (= 0.1) // - chamfers (deburr) - end_cham = 0.5; // 45 deg chamfer on the exposed ends of the two main T rods (crossbar tips + stem bottom) disc_cham = 0.5; // 45 deg chamfer on the disc's top + bottom rim edges hub_cham_top = 0.5; // 45 deg chamfer on the hub's TOP rim edge hub_bot_dia = 10.0; // the hub necks to this dia at its very BOTTOM (big shallow bottom cone) hub_cham_bot_h = 3.5; // axial height of the shallow bottom cone (10 dia -> 18 dia over 3.5mm) hub_bot_edge_cham = 0.5; // extra 45 deg chamfer easing the cone's top edge to the side (18->19 dia; total sloped 4mm) hub_cross_cs = 0.5; // even 0.5mm 45 deg chamfer swept around each crossbar-hole mouth (assembly lead-in) tang_cham = 0.1; // 45 deg lead-in on the tang tip (drops full-dia usable length 3.1 -> 3.0mm) $fn = 96; // - a rod along +Z, with optional 45 deg end chamfers -- module rod(len, dia, c_bot = 0, c_top = 0) { r = dia / 2; bot = c_bot > 0 ? [[r - c_bot, 0], [r, c_bot]] : [[r, 0]]; // bottom end top = c_top > 0 ? [[r, len - c_top], [r - c_top, len]] : [[r, len]]; // top end rotate_extrude() polygon(concat([[0, 0]], bot, top, [[0, len]])); } // - the top hub: 45 deg top rim + a large shallow bottom chamfer - module hub_solid() { R = hub_dia / 2; // full radius (9.5) rb = hub_bot_dia / 2; // small radius at the very bottom (5) bh = hub_cham_bot_h; // shallow bottom-cone height (3.5) ec = hub_bot_edge_cham; // 45 deg chamfer at the cone's top edge (0.5) ct = hub_cham_top; // top 45 deg chamfer (0.5) rotate_extrude() polygon([[0, 0], [rb, 0], // 10mm bottom face [R - ec, bh], // shallow cone up to (R-ec) at bh [R, bh + ec], // 45 deg edge chamfer out to full dia [R, hub_len - ct], [R - ct, hub_len], // straight side + top chamfer [0, hub_len]]); } // the crossbar bore through the hub (positioned) module cross_bore() { translate([0, 0, cross_z]) rotate([0, 90, 0]) translate([0, 0, -(hub_dia / 2 + 1)]) cylinder(h = hub_dia + 2, d = rod_dia); } // even 0.5mm 45 deg chamfer SWEPT around each crossbar-hole mouth. The mouth is a // compound-curved edge (round hole through a round hub), so a coaxial countersink // reads oval; instead we sweep a tiny 45 deg wedge along the ACTUAL edge curve // (where the bore, radius rh about X, meets the hub surface, radius R about Z). function cx_ex(rr, ph) = sqrt((hub_dia / 2) * (hub_dia / 2) - rr * rr * sin(ph) * sin(ph)); // surface X at bore-radius rr module cross_mouth_chamfer() { c = hub_cross_cs; rh = rod_dia / 2; ov = 0.4; N = 72; e = 0.001; // The wedge runs INTO the bore by 'ov' (kept on the 45 deg line) and pokes a // hair past the surface, so the smooth bore + hub surface trim its edges flush. for (s = [1, -1]) // +X and -X mouths for (i = [0 : N - 1]) { a = 360 * i / N; b = 360 * (i + 1) / N; hull() for (ph = [a, b]) for (p = [ [s * cx_ex(rh - ov, ph), (rh - ov) * sin(ph), cross_z + (rh - ov) * cos(ph)], // surface, inside bore [s * (cx_ex(rh - ov, ph) - (c + ov)), (rh - ov) * sin(ph), cross_z + (rh - ov) * cos(ph)], // deep (45 deg), inside bore [s * (cx_ex(rh + c, ph) + 0.02), (rh + c) * sin(ph), cross_z + (rh + c) * cos(ph)] // c out on the surface, nudged proud ]) translate(p) cube(e, center = true); } } // ---- individual parts -------------------------------------- // Each part carries the holes its mating parts press into, so a // standalone part view shows its real drilled/bored features - and // unioning all the parts fills those holes back (= the assembled tool). module part_stem() { // plain rod; bottom end chamfered color("#c0c0c0") rod(stem_len, rod_dia, end_cham, 0); } module part_crossbar() { // plain rod; both ends chamfered color("#c0c0c0") translate([0, 0, cross_z]) rotate([0, 90, 0]) translate([0, 0, -cross_len / 2]) rod(cross_len, rod_dia, end_cham, end_cham); } module part_disc() { // rims chamfered; stem + dowel holes THROUGH color("#c0c0c0") difference() { translate([0, 0, disc_z]) rod(disc_thick, disc_dia, disc_cham, disc_cham); translate([0, 0, disc_z - 1]) cylinder(h = disc_thick + 2, d = rod_dia); // stem hole translate([dowel_r, 0, disc_z - 1]) cylinder(h = disc_thick + 2, d = dowel_dia); // dowel hole } } module part_hub() { // blind stem bore up + crossbar bore, mouths chamfered even color("#c0c0c0") difference() { translate([0, 0, hub_bottom]) hub_solid(); translate([0, 0, hub_bottom - 1]) cylinder(h = stem_insert + 1, d = rod_dia); // blind stem bore (6mm) cross_bore(); // crossbar bore (through) cross_mouth_chamfer(); // even 45 deg mouth chamfer } } module part_dowel() { // dark tang dowel; tip chamfered color("#333333") translate([dowel_r, 0, disc_z - dowel_proud]) rod(dowel_len, dowel_dia, tang_cham, 0); } // ---- the assembled tool (pins fill their mating holes) ----- module t123() { part_stem(); part_crossbar(); part_disc(); part_hub(); part_dowel(); } // ---- output (flip 'view' at the top) ----------------------- if (view == "3D") t123(); else if (view == "Bars") { part_stem(); part_crossbar(); } // the two rods else if (view == "Hub") part_hub(); else if (view == "Disc") part_disc(); else if (view == "Dowel") part_dowel(); echo(str("stem = ", stem_len, " mm; crossbar = ", cross_len, " mm; rod = ", rod_dia, " mm dia"));