feat: Spring-loaded phone mount bracket for T-slot rail (Issue #535)

Parametric OpenSCAD design for 2020 T-slot rail phone mount bracket.
Adjustable width 60-85mm, spring-loaded cam quick-release lever,
vibration-dampening flexure rib grip pads. PETG 3D-printable, no supports.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
sl-mechanical 2026-03-07 09:49:10 -05:00
parent e67783f313
commit fc43135144

View File

@ -0,0 +1,504 @@
// ============================================================
// phone_mount_bracket.scad Spring-Loaded Phone Mount for T-Slot Rail
// Issue: #535 Agent: sl-mechanical Date: 2026-03-07
// ============================================================
//
// Parametric spring-loaded phone mount that clamps to the 2020 aluminium
// T-slot sensor rail. Adjustable phone width 6085 mm. Quick-release
// cam lever for tool-free phone swap. Vibration-damping flexure ribs
// on grip pads absorb motor/terrain vibration (PETG compliance).
//
// Design overview:
// - Fixed jaw + sliding jaw on a 40 mm guide rail (M4 rod)
// - Coil spring (Ø8 × 30 mm) compressed between jaw and end-stop
// spring pre-load keeps phone clamped at any width in range
// - Cam lever (printed PETG) rotates 90° to release / lock spring
// - Anti-vibration flexure ribs on both grip pad faces
// - Landscape or portrait orientation: bracket rotates on T-nut base
//
// Parts (STL exports):
// Part 1 tnut_base() Rail attachment base (universal)
// Part 2 fixed_jaw() Fixed bottom jaw + guide rail bosses
// Part 3 sliding_jaw() Spring-loaded sliding jaw
// Part 4 cam_lever() Quick-release cam lever
// Part 5 grip_pad() Flexure grip pad (print ×2, TPU optional)
// Part 6 assembly_preview() Full assembly
//
// Hardware BOM (per mount):
// 1× M4 × 60 mm SHCS guide rod + spring bolt
// 1× M4 hex nut end-stop on sliding jaw
// 1× Ø8 × 30 mm coil spring ~0.5 N/mm rate (spring clamping)
// 2× M3 × 16 mm SHCS T-nut base thumbscrew + arm bolts
// 1× M3 hex nut thumbscrew nut in T-nut
// 4× M2 × 8 mm SHCS grip pad retention bolts (optional)
//
// Dimensions:
// Phone width range : PHONE_W_MINPHONE_W_MAX (6085 mm) parametric
// Phone thickness : up to PHONE_THICK_MAX (12 mm) open-front jaw
// Phone height held : GRIP_SPAN (22 mm each jaw) portrait/landscape
// Overall bracket H : ~110 mm W: ~90 mm D: ~55 mm
//
// Print settings:
// Material : PETG (tnut_base, fixed_jaw, sliding_jaw, cam_lever)
// TPU 95A optional for grip_pad (or PETG for rigidity)
// Perimeters: 5 (structural parts), 3 (grip_pad)
// Infill : 40 % gyroid (jaws), 20 % (grip_pad)
// Supports : none needed (designed for FDM orientation)
// Layer ht : 0.2 mm
//
// Export commands:
// openscad phone_mount_bracket.scad -D 'RENDER="tnut_base_stl"' -o pm_tnut_base.stl
// openscad phone_mount_bracket.scad -D 'RENDER="fixed_jaw_stl"' -o pm_fixed_jaw.stl
// openscad phone_mount_bracket.scad -D 'RENDER="sliding_jaw_stl"' -o pm_sliding_jaw.stl
// openscad phone_mount_bracket.scad -D 'RENDER="cam_lever_stl"' -o pm_cam_lever.stl
// openscad phone_mount_bracket.scad -D 'RENDER="grip_pad_stl"' -o pm_grip_pad.stl
// ============================================================
$fn = 64;
e = 0.01; // epsilon for boolean clearance
// Phone parameters (adjust to target device)
PHONE_W_MIN = 60.0; // narrowest phone width supported (mm)
PHONE_W_MAX = 85.0; // widest phone width supported (mm)
PHONE_THICK_MAX = 12.0; // max phone body thickness incl. case (mm)
// Rail geometry (must match sensor_rail.scad)
RAIL_W = 20.0;
SLOT_OPEN = 6.0;
SLOT_INNER_W = 10.2;
SLOT_INNER_H = 5.8;
SLOT_NECK_H = 3.2;
// T-nut constants
TNUT_W = 9.8;
TNUT_H = 5.5;
TNUT_L = 12.0;
TNUT_M3_NUT_AF = 5.5;
TNUT_M3_NUT_H = 2.5;
TNUT_BOLT_D = 3.3; // M3 clearance
// Base plate geometry
BASE_FACE_W = 30.0;
BASE_FACE_H = 25.0;
BASE_FACE_T = SLOT_NECK_H + 1.5;
// Jaw geometry
JAW_BODY_W = 88.0; // jaw outer width (> PHONE_W_MAX for rim)
JAW_BODY_H = 28.0; // jaw height (Z) phone grip span
JAW_BODY_T = 14.0; // jaw depth (Y) phone cradled this deep
JAW_WALL_T = 4.0; // jaw side wall thickness
JAW_LIP_T = 3.0; // front retaining lip thickness
JAW_LIP_H = 5.0; // front lip height (retains phone)
PHONE_POCKET_D = PHONE_THICK_MAX + 0.5; // pocket depth for phone
// Guide rod / spring system
GUIDE_ROD_D = 4.3; // M4 clearance bore in sliding jaw
GUIDE_BOSS_D = 10.0; // boss OD around guide bore
GUIDE_BOSS_T = 6.0; // boss length
SPRING_OD = 8.5; // coil spring OD pocket (spring is Ø8)
SPRING_L = 32.0; // spring pocket length (spring compressed ~22 mm)
SPRING_SEAT_T = 3.0; // spring seat wall at end-stop boss
JAW_TRAVEL = PHONE_W_MAX - PHONE_W_MIN + 4.0; // max jaw travel (mm)
ARM_SPAN = PHONE_W_MAX + 2 * JAW_WALL_T + 8; // fixed jaw total width
// Cam lever geometry
CAM_R_MIN = 5.0; // cam small radius (engaged / clamped)
CAM_R_MAX = 9.0; // cam large radius (released, spring compressed)
CAM_THICK = 8.0; // cam disc thickness
CAM_HANDLE_L = 45.0; // lever arm length
CAM_HANDLE_W = 8.0; // lever handle width
CAM_HANDLE_T = 5.0; // lever handle thickness
CAM_BORE_D = 4.3; // M4 pivot bore
CAM_DETENT_D = 3.0; // detent ball pocket (3 mm bearing)
// Grip pad geometry (vibration dampening flexure ribs)
PAD_W = JAW_BODY_W - 2*JAW_WALL_T - 2; // pad width
PAD_H = JAW_BODY_H - 2; // pad height
PAD_T = 2.5; // pad body thickness
RIB_H = 1.5; // flexure rib height above pad face
RIB_W = 1.2; // rib width
RIB_PITCH = 5.0; // rib pitch (centre-to-centre)
RIB_COUNT = floor(PAD_W / RIB_PITCH) - 1;
// Arm geometry (base to jaw body)
ARM_REACH = 38.0; // distance from rail face to jaw centreline (+Y)
ARM_T = 4.0; // arm thickness
ARM_H = BASE_FACE_H;
// Fasteners
M2_D = 2.4;
M3_D = 3.3;
M4_D = 4.3;
M4_NUT_AF = 7.0; // M4 hex nut across-flats
M4_NUT_H = 3.2; // M4 hex nut height
// ============================================================
// RENDER DISPATCH
// ============================================================
RENDER = "assembly";
if (RENDER == "assembly") assembly_preview();
else if (RENDER == "tnut_base_stl") tnut_base();
else if (RENDER == "fixed_jaw_stl") fixed_jaw();
else if (RENDER == "sliding_jaw_stl") sliding_jaw();
else if (RENDER == "cam_lever_stl") cam_lever();
else if (RENDER == "grip_pad_stl") grip_pad();
// ============================================================
// ASSEMBLY PREVIEW
// ============================================================
module assembly_preview() {
// Ghost rail section (20 × 20 × 200)
%color("Silver", 0.30)
linear_extrude(200)
square([RAIL_W, RAIL_W], center = true);
// T-nut base at Z=80 on rail
color("OliveDrab", 0.85)
translate([0, 0, 80])
tnut_base();
// Fixed jaw assembly (centred, extending +Y from base)
color("DarkSlateGray", 0.85)
translate([0, SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
fixed_jaw();
// Sliding jaw shown at mid-travel (phone ~72 mm wide)
color("SteelBlue", 0.85)
translate([PHONE_W_MIN + (PHONE_W_MAX - PHONE_W_MIN)/2,
SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
sliding_jaw();
// Grip pads on both jaws
color("DimGray", 0.85) {
translate([0, SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
translate([JAW_WALL_T, JAW_BODY_T, JAW_BODY_H/2])
rotate([90, 0, 0])
grip_pad();
translate([PHONE_W_MIN + (PHONE_W_MAX - PHONE_W_MIN)/2,
SLOT_NECK_H + BASE_FACE_T + ARM_REACH, 80])
translate([-JAW_WALL_T - PAD_T, JAW_BODY_T, JAW_BODY_H/2])
rotate([90, 0, 180])
grip_pad();
}
// Cam lever shown in locked (clamped) position
color("OrangeRed", 0.85)
translate([ARM_SPAN/2 + 6,
SLOT_NECK_H + BASE_FACE_T + ARM_REACH + GUIDE_BOSS_D/2,
80 + JAW_BODY_H/2])
rotate([0, 0, 0])
cam_lever();
}
// ============================================================
// PART 1 T-NUT BASE
// ============================================================
// Standard 2020 T-slot rail attachment base.
// Identical interface to sensor_rail_brackets.scad universal_tnut_base().
// Arm extends in +Y; rail clamp bolt in -Y face.
//
// Print flat (face plate down), PETG, 5 perims, 60 % infill.
module tnut_base() {
difference() {
union() {
// Face plate (flush against rail outer face)
translate([-BASE_FACE_W/2, -BASE_FACE_T, 0])
cube([BASE_FACE_W, BASE_FACE_T, BASE_FACE_H]);
// T-nut neck (enters rail slot)
translate([-TNUT_W/2, 0, (BASE_FACE_H - TNUT_L)/2])
cube([TNUT_W, SLOT_NECK_H + e, TNUT_L]);
// T-nut body (wider, inside T-groove)
translate([-TNUT_W/2, SLOT_NECK_H - e, (BASE_FACE_H - TNUT_L)/2])
cube([TNUT_W, TNUT_H - SLOT_NECK_H + e, TNUT_L]);
// Arm stub (face plate jaw)
translate([-BASE_FACE_W/2, -BASE_FACE_T, 0])
cube([BASE_FACE_W, BASE_FACE_T + ARM_REACH, ARM_T]);
}
// M3 rail clamp bolt bore (centre of T-nut, through face plate)
translate([0, -BASE_FACE_T - e, BASE_FACE_H/2])
rotate([-90, 0, 0])
cylinder(d = TNUT_BOLT_D, h = BASE_FACE_T + TNUT_H + 2*e);
// M3 hex nut pocket (inside T-nut body)
translate([0, SLOT_NECK_H + 0.3, BASE_FACE_H/2])
rotate([-90, 0, 0])
cylinder(d = TNUT_M3_NUT_AF / cos(30),
h = TNUT_M3_NUT_H + 0.3,
$fn = 6);
// 2× M3 bolt holes for arm-to-jaw bolting
for (bx = [-10, 10])
translate([bx, ARM_REACH - BASE_FACE_T - e, ARM_T/2])
rotate([-90, 0, 0])
cylinder(d = M3_D, h = 8 + 2*e);
// Lightening slot in arm
translate([0, -BASE_FACE_T/2 + ARM_REACH/2, ARM_T/2])
cube([BASE_FACE_W - 12, ARM_REACH - 16, ARM_T + 2*e],
center = true);
}
}
// ============================================================
// PART 2 FIXED JAW
// ============================================================
// Fixed lower jaw of the clamping system. Phone sits in the pocket
// formed by the fixed jaw (bottom) and sliding jaw (top).
// Two guide bosses on the right wall carry the M4 guide rod + spring.
// The cam lever pivot boss is on the outer right face.
//
// Coordinate origin: centre-bottom of jaw body.
// Phone entry face: +Y (open front), phone pocket opens toward +Y.
// Fixed jaw left edge is at X = -JAW_BODY_W/2.
//
// Print jaw-pocket-face down, PETG, 5 perims, 40 % infill.
module fixed_jaw() {
difference() {
union() {
// Main jaw body
translate([-JAW_BODY_W/2, -JAW_BODY_T/2, 0])
cube([JAW_BODY_W, JAW_BODY_T, JAW_BODY_H]);
// Front retaining lip (keeps phone from falling forward)
translate([-JAW_BODY_W/2, JAW_BODY_T/2 - JAW_LIP_T, 0])
cube([JAW_BODY_W, JAW_LIP_T, JAW_LIP_H]);
// Guide boss right (outer, carries spring + end-stop)
translate([JAW_BODY_W/2, 0, JAW_BODY_H/2])
rotate([0, 90, 0])
cylinder(d = GUIDE_BOSS_D, h = GUIDE_BOSS_T);
// Cam lever pivot boss (right face, above guide boss)
translate([JAW_BODY_W/2, 0, JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
rotate([0, 90, 0])
cylinder(d = CAM_THICK + 4, h = 6);
// Arm attachment bosses (left side, connect to tnut_base)
for (bx = [-10, 10])
translate([bx, -JAW_BODY_T/2 - 8, ARM_T/2])
cylinder(d = 8, h = 8);
}
// Phone pocket (open-top U channel centred in jaw)
// Pocket opens toward +Y (front), phone drops in from above.
translate([0, -JAW_BODY_T/2 - e,
JAW_LIP_H])
cube([JAW_BODY_W - 2*JAW_WALL_T,
PHONE_POCKET_D + JAW_WALL_T,
JAW_BODY_H - JAW_LIP_H + e],
center = [true, false, false]);
// Guide rod bore (M4 clearance, through both guide bosses)
translate([-JAW_BODY_W/2 - e, 0, JAW_BODY_H/2])
rotate([0, 90, 0])
cylinder(d = GUIDE_ROD_D,
h = JAW_BODY_W + GUIDE_BOSS_T + 2*e);
// Spring pocket (coaxial with guide rod, in right boss)
translate([JAW_BODY_W/2 + e, 0, JAW_BODY_H/2])
rotate([0, -90, 0])
cylinder(d = SPRING_OD, h = SPRING_L);
// M4 hex nut pocket in spring-seat wall (end-stop nut)
translate([JAW_BODY_W/2 + GUIDE_BOSS_T + e, 0, JAW_BODY_H/2])
rotate([0, -90, 0])
cylinder(d = M4_NUT_AF / cos(30), h = M4_NUT_H + 0.5,
$fn = 6);
// Cam pivot bore (M4 pivot, through pivot boss)
translate([JAW_BODY_W/2 - e, 0, JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
rotate([0, 90, 0])
cylinder(d = CAM_BORE_D, h = 6 + 2*e);
// Arm attachment bolt holes (M3, to tnut_base arm stubs)
for (bx = [-10, 10])
translate([bx, -JAW_BODY_T/2 - 8 - e, ARM_T/2])
rotate([-90, 0, 0])
cylinder(d = M3_D, h = 12 + 2*e);
// Grip pad seats (recessed Ø1.5 mm, 2 mm deep, optional)
for (pz = [JAW_BODY_H * 0.3, JAW_BODY_H * 0.7])
for (px = [-PAD_W/4, PAD_W/4])
translate([px, -JAW_BODY_T/2 + PHONE_POCKET_D + 1, pz])
rotate([-90, 0, 0])
cylinder(d = M2_D, h = 10);
// Lightening pockets (non-structural core removal)
translate([0, 0, JAW_BODY_H/2])
cube([JAW_BODY_W - 2*JAW_WALL_T - 4,
JAW_BODY_T - 2*JAW_WALL_T,
JAW_BODY_H - JAW_LIP_H - 4],
center = true);
}
}
// ============================================================
// PART 3 SLIDING JAW
// ============================================================
// Upper clamping jaw. Slides along the M4 guide rod.
// Spring pushes this jaw toward the phone (inward).
// M4 hex nut on the guide rod limits maximum travel (full open).
// Cam lever pushes on this jaw face to compress spring (release).
//
// Coordinate origin same convention as fixed_jaw() for assembly.
// Jaw slides in +X direction (away from fixed jaw left wall).
//
// Print jaw-pocket-face down, PETG, 5 perims, 40 % infill.
module sliding_jaw() {
difference() {
union() {
// Main jaw body
translate([-JAW_WALL_T, -JAW_BODY_T/2, 0])
cube([JAW_BODY_W/2 + JAW_WALL_T, JAW_BODY_T, JAW_BODY_H]);
// Front retaining lip
translate([-JAW_WALL_T, JAW_BODY_T/2 - JAW_LIP_T, 0])
cube([JAW_BODY_W/2 + JAW_WALL_T, JAW_LIP_T, JAW_LIP_H]);
// Guide boss (carries guide rod, spring butts against face)
translate([-JAW_WALL_T - GUIDE_BOSS_T, 0, JAW_BODY_H/2])
rotate([0, 90, 0])
cylinder(d = GUIDE_BOSS_D, h = GUIDE_BOSS_T);
// Cam follower ear (contacts cam lever)
translate([-JAW_WALL_T - 2, 0,
JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
cube([4, CAM_THICK + 2, CAM_THICK + 2], center = true);
}
// Phone pocket (inner face, contacts phone side)
translate([-JAW_WALL_T - e, -JAW_BODY_T/2 - e, JAW_LIP_H])
cube([JAW_BODY_W/2 - JAW_WALL_T + e,
PHONE_POCKET_D + JAW_WALL_T + 2*e,
JAW_BODY_H - JAW_LIP_H + e]);
// Guide rod bore (M4 clearance through boss + jaw wall)
translate([-JAW_WALL_T - GUIDE_BOSS_T - e, 0, JAW_BODY_H/2])
rotate([0, 90, 0])
cylinder(d = GUIDE_ROD_D,
h = GUIDE_BOSS_T + JAW_WALL_T + 2*e);
// M4 nut pocket (end-stop nut, rear of guide boss)
translate([-JAW_WALL_T - GUIDE_BOSS_T - e, 0, JAW_BODY_H/2])
rotate([0, 90, 0])
cylinder(d = M4_NUT_AF / cos(30), h = M4_NUT_H + 1,
$fn = 6);
// Cam follower bore (M4 pivot passes through ear)
translate([-JAW_WALL_T - 2 - e, 0,
JAW_BODY_H/2 + GUIDE_BOSS_D + 4])
rotate([0, 90, 0])
cylinder(d = CAM_BORE_D, h = 6 + 2*e);
// Grip pad seats
for (pz = [JAW_BODY_H * 0.3, JAW_BODY_H * 0.7])
for (px = [JAW_BODY_W/8])
translate([px, -JAW_BODY_T/2 + PHONE_POCKET_D + 1, pz])
rotate([-90, 0, 0])
cylinder(d = M2_D, h = 10);
}
}
// ============================================================
// PART 4 CAM LEVER (QUICK-RELEASE)
// ============================================================
// Eccentric cam disc + integral handle lever.
// Rotates 90° on M4 pivot pin between CLAMPED and RELEASED states:
// CLAMPED : cam small radius (CAM_R_MIN) toward jaw spring pushes jaw
// RELEASED : cam large radius (CAM_R_MAX) toward jaw compresses spring
// by (CAM_R_MAX - CAM_R_MIN) = 4 mm, opening jaw
//
// Detent ball pocket (Ø3 mm) snaps into rail-dimple for each position.
// Handle points rearward (-Y) in clamped state for low profile.
//
// Print standing on cam edge (cam disc vertical), PETG, 5 perims, 40%.
module cam_lever() {
cam_offset = (CAM_R_MAX - CAM_R_MIN) / 2; // 2 mm eccentricity
union() {
difference() {
union() {
// Eccentric cam disc
// Offset so pivot bore is eccentric to disc profile
translate([cam_offset, 0, 0])
cylinder(r = CAM_R_MAX, h = CAM_THICK, center = true);
// Lever handle arm
hull() {
translate([cam_offset, 0, 0])
cylinder(r = CAM_R_MAX, h = CAM_THICK, center = true);
translate([cam_offset + CAM_HANDLE_L, 0, 0])
cylinder(r = CAM_HANDLE_W/2,
h = CAM_HANDLE_T, center = true);
}
}
// M4 pivot bore (through cam centre)
cylinder(d = CAM_BORE_D, h = CAM_THICK + 2*e, center = true);
// Detent pockets (2× Ø3 mm, at 0° and 90°)
// Pocket at 0° clamped detent
translate([CAM_R_MAX - 2, 0, CAM_THICK/2 - 1.5])
cylinder(d = CAM_DETENT_D + 0.2, h = 2);
// Pocket at 90° released detent
translate([0, CAM_R_MAX - 2, CAM_THICK/2 - 1.5])
cylinder(d = CAM_DETENT_D + 0.2, h = 2);
// Lightening recesses on cam disc face
for (a = [0, 60, 120, 180, 240, 300])
translate([cam_offset + (CAM_R_MAX - 4) * cos(a),
(CAM_R_MAX - 4) * sin(a), 0])
cylinder(d = 4, h = CAM_THICK + 2*e, center = true);
// Handle grip grooves
for (i = [0:4])
translate([cam_offset + 20 + i * 5, 0, 0])
rotate([90, 0, 0])
cylinder(d = 2.5, h = CAM_HANDLE_W + 2*e,
center = true);
}
}
}
// ============================================================
// PART 5 GRIP PAD (VIBRATION DAMPENING)
// ============================================================
// Flat pad with transverse flexure ribs that press against phone side.
// The rib profile (thin PETG fins) provides compliance in Z (vertical)
// absorbing vibration transmitted through the bracket.
// Optional: print in TPU 95A for superior damping.
// M2 bolts or adhesive-backed foam tape attach pad to jaw pocket face.
//
// Pad face (+Y) contacts phone. Mounting face (-Y) bonds to jaw.
// Ribs run parallel to Z axis (vertical).
//
// Print flat (mounting face down), PETG or TPU 95A, 3 perims, 20%.
module grip_pad() {
union() {
// Base plate
translate([-PAD_W/2, -PAD_T, -PAD_H/2])
cube([PAD_W, PAD_T, PAD_H]);
// Flexure ribs (transverse, dampening in Z)
// RIB_COUNT ribs spaced RIB_PITCH apart, centred on pad
for (i = [0 : RIB_COUNT - 1]) {
rx = -PAD_W/2 + RIB_PITCH/2 + i * RIB_PITCH;
if (abs(rx) <= PAD_W/2 - RIB_W/2) // stay within pad
translate([rx, 0, 0])
cube([RIB_W, RIB_H, PAD_H - 4], center = true);
}
// Corner retention nubs (M2 boss for optional bolt-through)
for (px = [-PAD_W/2 + 5, PAD_W/2 - 5])
for (pz = [-PAD_H/2 + 5, PAD_H/2 - 5])
translate([px, -PAD_T/2, pz])
difference() {
cylinder(d = 5, h = PAD_T, center = true);
cylinder(d = M2_D, h = PAD_T + 2*e, center = true);
}
}
}