Optimize case v1.1 with rounded corners and FDM cantilever snaps.

Adds catch windows, locating pegs, and a snap coupon for print tuning; keep lip alignment and rear DHT bay. Co-authored-by: Cursor <cursoragent@cursor.com>
2026-10-17 15:20:09 +08:00
parent c7d4b5a0c5
commit 892e9d04c6
8 changed files with 331 additions and 138 deletions
--- a/README.md
+++ b/README.md
@@ -41,11 +41,11 @@ pio device monitor -b 115200

 ## 3D 外壳

-桌面斜立分体壳（前框 + 后盖支架 + DHT11 通风仓），可直接打印：
+v1.1 圆角分体壳（前框 + 后盖 + 四侧悬臂卡扣 + 后盖 DHT 卡位），可直接打印：

- STL：[`cad/export/front.stl`](cad/export/front.stl)、[`cad/export/back.stl`](cad/export/back.stl)
+- STL：[`cad/export/front.stl`](cad/export/front.stl)、[`cad/export/back.stl`](cad/export/back.stl)、[`cad/export/snap_coupon.stl`](cad/export/snap_coupon.stl)（试打卡扣）
 - 浏览器预览：[`cad/viewer.html`](cad/viewer.html)（需本地 HTTP，见下）
- 参数源 / 说明：[`cad/README.md`](cad/README.md)
+- 参数与打印建议：[`cad/README.md`](cad/README.md)

 ```bash
 # 浏览器查看
@@ -53,11 +53,11 @@ python -m http.server 8765 --directory cad
 # 打开 http://localhost:8765/viewer.html

 # 重新导出 STL
-pip install trimesh manifold3d numpy
+pip install trimesh manifold3d numpy shapely
 python cad/generate_stl.py
 ```

-固定用 `4 × M3×10`；DHT11 装后盖通风仓，线接 CN1。
+合盖以卡扣为主、止口对齐；四角 `M3×10` 可选。建议 PETG；DHT11 装后盖背面卡位，线接 CN1。

 ## 项目结构

@@ -112,3 +112,4 @@ git reset --hard v1.0-case-closed
 | 2026-10-17 | 外壳改定：DHT11 后盖卡位微突出；前后盖止口合盖 |
 | 2026-10-17 | 去掉旁侧多余凸块；修复合盖对齐；DHT 改为后盖平面卡位 |
 | 2026-10-17 | 打标签 `v1.0-case-closed` 作为可回滚稳定版 |
+| 2026-10-17 | 外壳 v1.1：外圆角 R3.5、四侧悬臂卡扣、定位柱、卡扣试打样件 |
--- a/cad/README.md
+++ b/cad/README.md
@@ -1,21 +1,39 @@
-# CYD 温湿度仪表盘 3D 外壳
+# CYD 温湿度仪表盘 3D 外壳（v1.1）

-## 结构说明（当前版）
+## 结构说明

-只有两件：**前框** + **后盖**。
+只有两件：**前框** + **后盖**。外轮廓圆角 R=3.5mm，主要靠 **4 处悬臂卡扣** 合盖（止口仍保留对齐；四角 M3 可选）。

 | 部位 | 作用 |
 |------|------|
-| 前框 | 屏窗；公止口，合盖时插入后盖 |
-| 后盖 | 装板子；母止口；**背面中心 DHT11 卡位通风口**（探头微突出约 1.6mm） |
-| DHT 示意 | 预览里蓝色/灰块，表示传感器装在后盖背面卡位里 |
+| 前框 | 屏窗；公止口；长边各 2 根悬臂卡扣（钩朝外） |
+| 后盖 | 装板子；母止口；卡扣窗口 + 卡台；**背面中心 DHT11 卡位通风口**（探头微突出约 1.6mm） |
+| 定位柱 | 四角短 peg / 孔，合盖防错位 |
+| `snap_coupon.stl` | 单独试打卡扣样件，调间隙后再打整壳 |

-**没有**外壳旁边的大“格子”。旧版里那两块是：侧向支脚块、外挂 DHT 仓——已删除，避免误解。
+**没有**外壳旁边的大“格子”（旧支脚块 / 外挂仓已删）。
+
+## 卡扣参数（按 FDM 常见经验）
+
+参考悬臂卡扣实践（应变控制、根部过渡、配合间隙、PETG 反复开合更稳）：
+
+| 参数 | 本壳取值 | 说明 |
+|------|----------|------|
+| 自由臂长 L | 11 mm | 偏短可再加长降低应变 |
+| 根厚 / 尖厚 | 1.7 → 0.95 mm | 锥形臂，应力分散 |
+| 钩深 undercut | 0.75 mm | 含 lead-in 斜面 |
+| 侧向间隙 | 0.45 mm | FDM 合盖/卡扣常用约 0.4–0.5 |
+| 止口间隙 | 0.45 mm | 同左 |
+| 材料建议 | **PETG** | PLA 可试装，反复开合易脆 |
+
+打印：卡扣臂尽量落在 **XY 弯曲平面**（不要让弯曲撕开层层）。先打 `snap_coupon.stl`，太紧就略加大间隙或减钩深。

 ## 合盖

-前框止口落入后盖槽；预览默认合盖（开合度 0%）。  
-对齐数据在 `export/mate.json`。
+前框止口落入后盖槽，卡扣钩入后盖窗口卡台；预览默认合盖（开合度 0%）。  
+对齐数据在 `export/mate.json`（`version: 1.1-snaps`）。
+
+稳定旧版（无卡扣、仅止口）标签：仓库根 README 的 `v1.0-case-closed`。

 ## 浏览器预览

@@ -31,11 +49,13 @@ python -m http.server 8765 --directory cad
 ## 导出 STL

 ```bash
-pip install trimesh manifold3d numpy
+pip install trimesh manifold3d numpy shapely
 python cad/generate_stl.py
 ```

+输出：`export/front.stl`、`back.stl`、`snap_coupon.stl`、`mate.json`。
+
 ## 装配

 1. DHT11 从**后盖背面**按入中心卡位，探头朝外略突出，线进腔内接 CN1/GPIO22  
-2. CYD 放入后盖，前框合盖，四角 M3×10 可选固定  
+2. CYD 放入后盖，前框对准止口/定位柱合盖，听四侧卡扣入位；四角 M3×10 可选  
--- a/cad/export/back.stl
+++ b/cad/export/back.stl
--- a/cad/export/front.stl
+++ b/cad/export/front.stl
--- a/cad/export/mate.json
+++ b/cad/export/mate.json
@@ -1,8 +1,14 @@
 {
-  "outer_l": 91.5,
-  "outer_w": 55.5,
+  "outer_l": 91.6,
+  "outer_w": 55.599999999999994,
  "front_body_h": 7.2,
  "back_body_h": 10.4,
-  "lip_h": 2.2,
-  "dht_proud": 1.6
+  "lip_h": 2.0,
+  "dht_proud": 1.6,
+  "corner_r": 3.5,
+  "snap_w": 6.5,
+  "snap_l": 11.0,
+  "snap_hook": 0.75,
+  "lip_clear": 0.45,
+  "version": "1.1-snaps"
 }
--- a/cad/export/snap_coupon.stl
+++ b/cad/export/snap_coupon.stl
--- a/cad/generate_stl.py
+++ b/cad/generate_stl.py
@@ -1,31 +1,59 @@
 #!/usr/bin/env python3
 """
-CYD climate case — clean clamshell.
+CYD climate case v1.1 — rounded clamshell + FDM snap clips.

- Front: screen bezel + male lip
- Back: cavity + female groove + DHT11 snap pocket flush in back wall (tip proud ~1.6mm)
- No side “boxes”: removed bulky stand block and external DHT hang-on bay
+Design refs (FDM snap-fit best practice):
+  - Cantilever L≈12–16mm, root t≈1.6–2.0mm, width≥5mm
+  - Undercut ≈0.7mm, lead-in ≈35°, root fillet ≥0.5·t
+  - Mating clearance ≈0.4–0.5mm (FDM)
+  - Prefer PETG for repeated open/close; print snap arms in XY bend plane
+
+Features:
+  - Outer R=3.5mm / inner R≈2.0mm rounded shell
+  - 4 side cantilever snaps (front) + catch windows (back)
+  - Corner locating pegs / sockets for 合盖对齐
+  - DHT11 flush rear pocket with slight proud grill
+  - Optional M3 bosses kept as backup
 """

 from __future__ import annotations

+import json
 from pathlib import Path

+import numpy as np
 import trimesh
-from trimesh.creation import box, cylinder
+from shapely.geometry import Point, box
+from trimesh.creation import cylinder, extrude_polygon

+# ---- board ----
 PCB_L, PCB_W = 86.0, 50.0
 MH_INSET = 4.0
 DISP_X, DISP_L, DISP_W, DISP_H = 8.0, 69.0, 50.0, 4.0
 VIEW_L, VIEW_W, VIEW_IX, VIEW_IY = 59.5, 45.0, 7.0, 2.5
-WALL, GAP = 2.4, 0.35
+
+# ---- shell ----
+WALL, GAP = 2.4, 0.40
+CORNER_R = 3.5
+INNER_R = 2.0
 BEZEL_T = 2.2
 CAVITY = 8.0
-LIP_H, LIP_CLEAR = 2.2, 0.2
+LIP_H = 2.0
+LIP_CLEAR = 0.45  # FDM clearance around lip
 USB_W, USB_H, USB_Y = 15.0, 9.0, 30.5
 SCREW, BOSS_OD, BOSS_ID = 3.3, 7.0, 2.5

-# DHT11 module pocket (from OUTSIDE of back face z=0)
+# ---- snap (cantilever) ----
+SNAP_W = 6.5
+SNAP_L = 11.0          # free length
+SNAP_T_ROOT = 1.7
+SNAP_T_TIP = 0.95
+SNAP_HOOK = 0.75       # undercut
+SNAP_LEAD = 0.9        # lead-in ramp height along arm
+SNAP_CLEAR = 0.45      # side gap around moving arm
+SNAP_Z_ROOT = 1.2      # root starts below front rim into skirt
+
+# ---- DHT ----
 DHT_L, DHT_W, DHT_H = 16.0, 12.5, 7.5
 DHT_PROUD = 1.6

@@ -34,8 +62,7 @@ INNER_W = PCB_W + 2 * GAP
 OUTER_L = INNER_L + 2 * WALL
 OUTER_W = INNER_W + 2 * WALL
 SKIRT = DISP_H + 1.0
-# Back total height to mating plane (top of female groove floor)
-BACK_BODY_H = WALL + CAVITY  # rim starts here
+BACK_BODY_H = WALL + CAVITY
 FRONT_BODY_H = BEZEL_T + SKIRT

 MH = [
@@ -45,6 +72,17 @@ MH = [
    (MH_INSET, PCB_W - MH_INSET),
 ]

+# snap centers along long sides (x), inset from ends
+SNAP_XS = [OUTER_L * 0.28, OUTER_L * 0.72]
+
+
+def rounded_prism(l: float, w: float, h: float, r: float, z0: float = 0.0) -> trimesh.Trimesh:
+    r = min(r, l / 2 - 0.05, w / 2 - 0.05)
+    poly = box(r, r, l - r, w - r).buffer(r, resolution=8)
+    mesh = extrude_polygon(poly, height=h)
+    mesh.apply_translation([0, 0, z0])
+    return mesh
+

 def aabb(x0, y0, z0, x1, y1, z1) -> trimesh.Trimesh:
    xa, xb = sorted((float(x0), float(x1)))
@@ -52,8 +90,8 @@ def aabb(x0, y0, z0, x1, y1, z1) -> trimesh.Trimesh:
    za, zb = sorted((float(z0), float(z1)))
    dx, dy, dz = xb - xa, yb - ya, zb - za
    if min(dx, dy, dz) < 1e-6:
-        raise ValueError(f"degenerate {[xa, ya, za, xb, yb, zb]}")
-    m = box(extents=[dx, dy, dz])
+        raise ValueError(f"degenerate box {xa,ya,za,xb,yb,zb}")
+    m = trimesh.creation.box(extents=[dx, dy, dz])
    m.apply_translation([xa + dx / 2, ya + dy / 2, za + dz / 2])
    return m

@@ -65,168 +103,295 @@ def U(*ms: trimesh.Trimesh) -> trimesh.Trimesh:
    return r


-def D(a: trimesh.Trimesh, *ss: trimesh.Trimesh) -> trimesh.Trimesh:
+def Diff(a: trimesh.Trimesh, *ss: trimesh.Trimesh) -> trimesh.Trimesh:
    r = a
    for s in ss:
        r = r.difference(s, engine="manifold")
    return r


-def make_front() -> trimesh.Trimesh:
+def cantilever_snap(x_center: float, y_wall: float, outward_sign: int) -> trimesh.Trimesh:
    """
-    Z=0: outer screen face
-    Z=FRONT_BODY_H: open rim with male lip extending to FRONT_BODY_H+LIP_H
+    Snap arm on front: root near FRONT_BODY_H, extends +Z (into back when closed).
+    Hook faces outward (+/- Y).
+    outward_sign: +1 for +Y wall (hook +Y), -1 for -Y wall.
    """
-    body = aabb(0, 0, 0, OUTER_L, OUTER_W, FRONT_BODY_H)
-    hollow = aabb(WALL, WALL, BEZEL_T, OUTER_L - WALL, OUTER_W - WALL, FRONT_BODY_H + 1)
+    # Build in local: arm along +Z, thickness in Y, width in X
+    # Root fillet approximated by stepped thickening
+    pieces = []
+    n = 6
+    for i in range(n):
+        t = i / (n - 1)
+        # taper thickness root -> tip
+        th = SNAP_T_ROOT * (1 - t) + SNAP_T_TIP * t
+        z0 = FRONT_BODY_H - SNAP_Z_ROOT + t * (SNAP_L + SNAP_Z_ROOT)
+        z1 = FRONT_BODY_H - SNAP_Z_ROOT + (t + 1 / n) * (SNAP_L + SNAP_Z_ROOT) + 0.05
+        # arm sits inside wall face, hook later
+        if outward_sign > 0:
+            y0 = y_wall - WALL + SNAP_CLEAR
+            y1 = y0 + th
+        else:
+            y1 = y_wall + WALL - SNAP_CLEAR
+            y0 = y1 - th
+        pieces.append(aabb(x_center - SNAP_W / 2, y0, z0, x_center + SNAP_W / 2, y1, z1))

+    arm = U(*pieces)
+
+    # hook wedge at tip (lead-in ramp) — min thickness keeps manifold volumes valid
+    tip_z = FRONT_BODY_H - SNAP_Z_ROOT + SNAP_L + SNAP_Z_ROOT
+    hook_steps = []
+    for i in range(5):
+        t = (i + 1) / 5  # start above 0 so h>0
+        h = max(0.25, SNAP_HOOK * min(1.0, t / 0.55))
+        z0 = tip_z - SNAP_LEAD + (i / 5) * SNAP_LEAD
+        z1 = tip_z - SNAP_LEAD + ((i + 1) / 5) * SNAP_LEAD + 0.08
+        if outward_sign > 0:
+            y0 = y_wall - WALL + SNAP_CLEAR + SNAP_T_TIP
+            y1 = y0 + h
+        else:
+            y1 = y_wall + WALL - SNAP_CLEAR - SNAP_T_TIP
+            y0 = y1 - h
+        hook_steps.append(aabb(x_center - SNAP_W / 2 + 0.4, y0, z0, x_center + SNAP_W / 2 - 0.4, y1, z1))
+    return U(arm, *hook_steps)
+
+
+def catch_window(x_center: float, y_wall: float, outward_sign: int) -> trimesh.Trimesh:
+    """Opening / ledge cut in back wall for snap hook."""
+    # Window through wall where hook passes, then a ledge below for catch
+    win_h = SNAP_L + 2.5
+    z0 = BACK_BODY_H - 1.0
+    z1 = z0 + win_h
+    if outward_sign > 0:
+        return aabb(
+            x_center - SNAP_W / 2 - SNAP_CLEAR,
+            y_wall - WALL - 0.2,
+            z0,
+            x_center + SNAP_W / 2 + SNAP_CLEAR,
+            y_wall + 0.6,
+            z1,
+        )
+    return aabb(
+        x_center - SNAP_W / 2 - SNAP_CLEAR,
+        y_wall - 0.6,
+        z0,
+        x_center + SNAP_W / 2 + SNAP_CLEAR,
+        y_wall + WALL + 0.2,
+        z1,
+    )
+
+
+def catch_ledge(x_center: float, y_wall: float, outward_sign: int) -> trimesh.Trimesh:
+    """Internal ledge the hook seats under (retention)."""
+    z0 = BACK_BODY_H + 0.3
+    z1 = z0 + 1.4
+    if outward_sign > 0:
+        return aabb(
+            x_center - SNAP_W / 2 + 0.3,
+            OUTER_W - WALL - 0.2,
+            z0,
+            x_center + SNAP_W / 2 - 0.3,
+            OUTER_W - WALL + SNAP_HOOK + 0.3,
+            z1,
+        )
+    return aabb(
+        x_center - SNAP_W / 2 + 0.3,
+        WALL - SNAP_HOOK - 0.3,
+        z0,
+        x_center + SNAP_W / 2 - 0.3,
+        WALL + 0.2,
+        z1,
+    )
+
+
+def make_front() -> trimesh.Trimesh:
+    body = rounded_prism(OUTER_L, OUTER_W, FRONT_BODY_H, CORNER_R, 0)
+    hollow = rounded_prism(INNER_L, INNER_W, FRONT_BODY_H + 1, INNER_R, BEZEL_T)
+    hollow.apply_translation([WALL, WALL, 0])
+    out = Diff(body, hollow)
+
+    # view + pocket
    vx = WALL + GAP + DISP_X + VIEW_IX
    vy = WALL + GAP + VIEW_IY
-    view = aabb(vx - 0.2, vy - 0.2, -0.5, vx + VIEW_L + 0.2, vy + VIEW_W + 0.2, BEZEL_T + 0.5)
-
+    out = Diff(out, aabb(vx - 0.2, vy - 0.2, -0.5, vx + VIEW_L + 0.2, vy + VIEW_W + 0.2, BEZEL_T + 0.5))
    sx = WALL + GAP + DISP_X - 0.2
-    pocket = aabb(
-        sx, WALL + GAP - 0.1, BEZEL_T - 0.05,
-        sx + DISP_L + 0.4, WALL + GAP + DISP_W + 0.1, BEZEL_T + DISP_H + 0.6,
+    out = Diff(
+        out,
+        aabb(sx, WALL + GAP - 0.1, BEZEL_T - 0.05, sx + DISP_L + 0.4, WALL + GAP + DISP_W + 0.1, BEZEL_T + DISP_H + 0.6),
    )
-    out = D(body, hollow, view, pocket)

-    # male lip: thin wall ring protruding past rim
-    lip_out = aabb(
-        WALL - 1.0, WALL - 1.0, FRONT_BODY_H - 0.05,
-        OUTER_L - (WALL - 1.0), OUTER_W - (WALL - 1.0), FRONT_BODY_H + LIP_H,
-    )
-    lip_in = aabb(
-        WALL + LIP_CLEAR, WALL + LIP_CLEAR, FRONT_BODY_H - 0.2,
-        OUTER_L - WALL - LIP_CLEAR, OUTER_W - WALL - LIP_CLEAR, FRONT_BODY_H + LIP_H + 0.5,
-    )
-    out = U(out, D(lip_out, lip_in))
+    # male lip (rounded ring approx via outer-inner)
+    lip_out = rounded_prism(OUTER_L - 1.2, OUTER_W - 1.2, LIP_H, CORNER_R - 0.6, FRONT_BODY_H - 0.05)
+    lip_out.apply_translation([0.6, 0.6, 0])
+    lip_in = rounded_prism(INNER_L + LIP_CLEAR * 2, INNER_W + LIP_CLEAR * 2, LIP_H + 0.6, INNER_R, FRONT_BODY_H - 0.2)
+    lip_in.apply_translation([WALL - LIP_CLEAR, WALL - LIP_CLEAR, 0])
+    out = U(out, Diff(lip_out, lip_in))

+    # locating pegs (导柱) near corners — stick into back sockets
+    pegs = []
+    for px, py in [(8.0, 8.0), (OUTER_L - 8.0, 8.0), (OUTER_L - 8.0, OUTER_W - 8.0), (8.0, OUTER_W - 8.0)]:
+        peg = cylinder(radius=1.4, height=LIP_H + 2.2, sections=20)
+        peg.apply_translation([px, py, FRONT_BODY_H + (LIP_H + 2.2) / 2 - 0.3])
+        pegs.append(peg)
+    out = U(out, *pegs)
+
+    # 4 snaps on long sides
+    snaps = []
+    for x in SNAP_XS:
+        snaps.append(cantilever_snap(x, OUTER_W, +1))
+        snaps.append(cantilever_snap(x, 0.0, -1))
+    out = U(out, *snaps)
+
+    # optional screw holes (backup)
    for px, py in MH:
-        hole = cylinder(radius=SCREW / 2 + 0.1, height=FRONT_BODY_H + LIP_H + 4, sections=28)
+        hole = cylinder(radius=SCREW / 2 + 0.1, height=FRONT_BODY_H + LIP_H + 6, sections=24)
        hole.apply_translation([WALL + GAP + px, WALL + GAP + py, FRONT_BODY_H / 2])
-        out = D(out, hole)
+        out = Diff(out, hole)

    out.merge_vertices()
    return out


 def make_back() -> trimesh.Trimesh:
-    """
-    Z=0: exterior back face (DHT grill here, slightly proud)
-    Z=BACK_BODY_H: mating plane; female groove from BACK_BODY_H to BACK_BODY_H+LIP_H
-    """
    total_h = BACK_BODY_H + LIP_H
-    body = aabb(0, 0, 0, OUTER_L, OUTER_W, total_h)
-    cavity = aabb(WALL, WALL, WALL, OUTER_L - WALL, OUTER_W - WALL, total_h + 1)
-    out = D(body, cavity)
+    body = rounded_prism(OUTER_L, OUTER_W, total_h, CORNER_R, 0)
+    cavity = rounded_prism(INNER_L, INNER_W, total_h + 1, INNER_R, WALL)
+    cavity.apply_translation([WALL, WALL, 0])
+    out = Diff(body, cavity)

-    # female groove: cut a channel in the top rim for the male lip
-    # outer wall of groove
-    groove = aabb(
-        WALL - 1.0 - LIP_CLEAR, WALL - 1.0 - LIP_CLEAR, BACK_BODY_H + 0.1,
-        OUTER_L - (WALL - 1.0 - LIP_CLEAR), OUTER_W - (WALL - 1.0 - LIP_CLEAR), total_h + 0.2,
-    )
-    groove_keep = aabb(
-        WALL + 0.05, WALL + 0.05, BACK_BODY_H - 0.1,
-        OUTER_L - WALL - 0.05, OUTER_W - WALL - 0.05, total_h + 0.3,
-    )
-    out = D(out, D(groove, groove_keep))
+    # female groove for lip
+    groove = rounded_prism(OUTER_L - 0.8, OUTER_W - 0.8, LIP_H + 0.3, CORNER_R - 0.4, BACK_BODY_H + 0.1)
+    groove.apply_translation([0.4, 0.4, 0])
+    keep = rounded_prism(INNER_L + 0.2, INNER_W + 0.2, LIP_H + 0.6, INNER_R, BACK_BODY_H - 0.1)
+    keep.apply_translation([WALL - 0.1, WALL - 0.1, 0])
+    out = Diff(out, Diff(groove, keep))
+
+    # locating sockets
+    for px, py in [(8.0, 8.0), (OUTER_L - 8.0, 8.0), (OUTER_L - 8.0, OUTER_W - 8.0), (8.0, OUTER_W - 8.0)]:
+        sock = cylinder(radius=1.55, height=3.2, sections=20)
+        sock.apply_translation([px, py, BACK_BODY_H + 1.4])
+        out = Diff(out, sock)
+
+    # snap catch windows + ledges
+    for x in SNAP_XS:
+        out = Diff(out, catch_window(x, OUTER_W, +1))
+        out = Diff(out, catch_window(x, 0.0, -1))
+        out = U(out, catch_ledge(x, OUTER_W, +1))
+        out = U(out, catch_ledge(x, 0.0, -1))

    # USB
    uy0 = WALL + GAP + USB_Y - USB_W / 2
-    out = D(out, aabb(-0.5, uy0, WALL + 1.0, WALL + 1.0, uy0 + USB_W, WALL + 1.0 + USB_H))
+    out = Diff(out, aabb(-0.5, uy0, WALL + 1.0, WALL + 1.0, uy0 + USB_W, WALL + 1.0 + USB_H))

-    # button holes
+    # buttons
    for y in (12.0, 22.0):
-        btn = cylinder(radius=2.2, height=WALL + 2, sections=20)
+        btn = cylinder(radius=2.2, height=WALL + 2, sections=18)
        btn.apply_translation([WALL + GAP + 10, WALL + GAP + y, WALL / 2])
-        out = D(out, btn)
+        out = Diff(out, btn)

-    # screw bosses
+    # M3 bosses backup
    bosses = []
    for px, py in MH:
        x, y = WALL + GAP + px, WALL + GAP + py
-        boss = cylinder(radius=BOSS_OD / 2, height=CAVITY - 0.5, sections=28)
+        boss = cylinder(radius=BOSS_OD / 2, height=CAVITY - 0.5, sections=24)
        boss.apply_translation([x, y, WALL + (CAVITY - 0.5) / 2])
-        hole = cylinder(radius=BOSS_ID / 2, height=CAVITY + 1, sections=20)
+        hole = cylinder(radius=BOSS_ID / 2, height=CAVITY + 1, sections=18)
        hole.apply_translation([x, y, WALL + CAVITY / 2])
-        bosses.append(D(boss, hole))
+        bosses.append(Diff(boss, hole))
    out = U(out, *bosses)

-    # ---- DHT11 flush pocket in back wall (NOT a side box) ----
-    # Center on back face
-    cx = OUTER_L * 0.5
-    cy = OUTER_W * 0.5
-    # Pocket carved from outside into wall+cavity enough for module
-    pocket = aabb(
-        cx - DHT_L / 2 - 0.3, cy - DHT_W / 2 - 0.3, -0.05,
-        cx + DHT_L / 2 + 0.3, cy + DHT_W / 2 + 0.3, WALL + DHT_H - 1.0,
+    # DHT pocket + proud rounded grill
+    cx, cy = OUTER_L / 2, OUTER_W / 2
+    out = Diff(
+        out,
+        aabb(cx - DHT_L / 2 - 0.3, cy - DHT_W / 2 - 0.3, -0.05, cx + DHT_L / 2 + 0.3, cy + DHT_W / 2 + 0.3, WALL + DHT_H - 1.0),
    )
-    out = D(out, pocket)
-
-    # Snap rails (卡位) left/right inside pocket — thin ledges
-    rail_z0, rail_z1 = 1.2, 1.2 + 2.2
-    left = aabb(cx - DHT_L / 2 - 0.3, cy - 3.2, rail_z0, cx - DHT_L / 2 + 1.0, cy + 3.2, rail_z1)
-    right = aabb(cx + DHT_L / 2 - 1.0, cy - 3.2, rail_z0, cx + DHT_L / 2 + 0.3, cy + 3.2, rail_z1)
-    # bottom stop (prevents falling inward)
-    stop = aabb(cx - 5, cy - DHT_W / 2 + 0.5, WALL + DHT_H - 2.2, cx + 5, cy + DHT_W / 2 - 0.5, WALL + DHT_H - 1.0)
-    out = U(out, left, right, stop)
-
-    # Proud grill ring on exterior (the only intentional protrusion)
-    grill_ring = aabb(
-        cx - DHT_L / 2 - 1.0, cy - DHT_W / 2 - 1.0, -DHT_PROUD,
-        cx + DHT_L / 2 + 1.0, cy + DHT_W / 2 + 1.0, 0.05,
+    out = U(
+        out,
+        aabb(cx - DHT_L / 2 - 0.3, cy - 3.2, 1.2, cx - DHT_L / 2 + 1.0, cy + 3.2, 3.4),
+        aabb(cx + DHT_L / 2 - 1.0, cy - 3.2, 1.2, cx + DHT_L / 2 + 0.3, cy + 3.2, 3.4),
+        aabb(cx - 5, cy - DHT_W / 2 + 0.5, WALL + DHT_H - 2.2, cx + 5, cy + DHT_W / 2 - 0.5, WALL + DHT_H - 1.0),
    )
-    grill_hole = aabb(
-        cx - DHT_L / 2 + 1.5, cy - DHT_W / 2 + 1.5, -DHT_PROUD - 0.2,
-        cx + DHT_L / 2 - 1.5, cy + DHT_W / 2 - 1.5, 0.2,
+    # rounded proud grill via buffered square
+    grill_poly = box(cx - DHT_L / 2 - 0.8, cy - DHT_W / 2 - 0.8, cx + DHT_L / 2 + 0.8, cy + DHT_W / 2 + 0.8).buffer(
+        1.2, resolution=6
    )
-    # slot vents in proud face
+    grill = extrude_polygon(grill_poly, height=DHT_PROUD + 0.1)
+    grill.apply_translation([0, 0, -DHT_PROUD])
+    hole_poly = box(cx - DHT_L / 2 + 1.6, cy - DHT_W / 2 + 1.6, cx + DHT_L / 2 - 1.6, cy + DHT_W / 2 - 1.6).buffer(
+        0.8, resolution=5
+    )
+    ghole = extrude_polygon(hole_poly, height=DHT_PROUD + 0.4)
+    ghole.apply_translation([0, 0, -DHT_PROUD - 0.2])
    slots = []
    for i in range(4):
-        slots.append(aabb(
-            cx - 5 + i * 2.8, cy - 4.5, -DHT_PROUD - 0.2,
-            cx - 5 + i * 2.8 + 1.2, cy + 4.5, 0.2,
-        ))
-    out = U(out, D(grill_ring, grill_hole, *slots))
-
-    # tiny wire path already open via pocket into cavity
-
-    # Simple thin kickstand rib (not a hollow “格子”) — optional small triangle
-    # Skip bulky stand entirely per user feedback.
+        slots.append(
+            aabb(cx - 5 + i * 2.8, cy - 4.2, -DHT_PROUD - 0.2, cx - 5 + i * 2.8 + 1.2, cy + 4.2, 0.15)
+        )
+    out = U(out, Diff(grill, ghole, *slots))

    out.merge_vertices()
    return out


+def make_snap_coupon() -> trimesh.Trimesh:
+    """Small test piece: one snap + one catch for tuning before full print."""
+    base = aabb(0, 0, 0, 40, 28, 3)
+    # fake front strip with one snap
+    strip = aabb(5, 20, 3, 35, 28, 3 + FRONT_BODY_H * 0.35)
+    snap = cantilever_snap(20, 28, +1)
+    # shift snap down a bit for coupon
+    front = U(strip, snap)
+    # fake back catch wall
+    wall = aabb(5, 0, 0, 35, 3.2, 18)
+    win = catch_window(20, 3.2, +1)
+    # remap catch to coupon coords roughly
+    catch = aabb(20 - SNAP_W / 2 - 0.5, -0.2, 8, 20 + SNAP_W / 2 + 0.5, 3.5, 18)
+    ledge = aabb(20 - SNAP_W / 2 + 0.3, 2.5, 10, 20 + SNAP_W / 2 - 0.3, 2.5 + SNAP_HOOK + 0.4, 11.4)
+    back = U(Diff(wall, catch), ledge)
+    # place back beside front
+    back.apply_translation([0, -8, 0])
+    label = aabb(2, 12, 3, 3.2, 18, 4.5)  # marker nub
+    return U(base, front, back, label)
+
+
 def main() -> None:
    out = Path(__file__).resolve().parent / "export"
    out.mkdir(parents=True, exist_ok=True)
-    print("front…")
+
+    print("front (rounded + snaps)…")
    front = make_front()
-    print("back…")
+    print("back (rounded + catches)…")
    back = make_back()
+    print("snap coupon…")
+    coupon = make_snap_coupon()
+
    front.export(out / "front.stl")
    back.export(out / "back.stl")
+    coupon.export(out / "snap_coupon.stl")

-    # write mate info for viewer
-    meta = out / "mate.json"
-    meta.write_text(
-        "{\n"
-        f'  "outer_l": {OUTER_L},\n'
-        f'  "outer_w": {OUTER_W},\n'
-        f'  "front_body_h": {FRONT_BODY_H},\n'
-        f'  "back_body_h": {BACK_BODY_H},\n'
-        f'  "lip_h": {LIP_H},\n'
-        f'  "dht_proud": {DHT_PROUD}\n'
-        "}\n",
+    meta = {
+        "outer_l": OUTER_L,
+        "outer_w": OUTER_W,
+        "front_body_h": FRONT_BODY_H,
+        "back_body_h": BACK_BODY_H,
+        "lip_h": LIP_H,
+        "dht_proud": DHT_PROUD,
+        "corner_r": CORNER_R,
+        "snap_w": SNAP_W,
+        "snap_l": SNAP_L,
+        "snap_hook": SNAP_HOOK,
+        "lip_clear": LIP_CLEAR,
+        "version": "1.1-snaps",
+    }
+    (out / "mate.json").write_text(
+        json.dumps(meta, indent=2) + "\n",
        encoding="utf-8",
    )
-    print(f"front {front.extents} watertight={front.is_watertight}")
-    print(f"back  {back.extents} watertight={back.is_watertight}")
-    print("closed stack height ≈", BACK_BODY_H + FRONT_BODY_H, "mm (lips nest, not add full)")
-    print("Wrote STLs + mate.json")
+
+    print(f"front {front.extents} wt={front.is_watertight}")
+    print(f"back  {back.extents} wt={back.is_watertight}")
+    print(f"coupon {coupon.extents} wt={coupon.is_watertight}")
+    print("Wrote front/back/snap_coupon + mate.json")


 if __name__ == "__main__":
--- a/cad/viewer.html
+++ b/cad/viewer.html
@@ -62,8 +62,8 @@
    </div>

    <p class="faq">
-      后盖中心微凸的是 <b>DHT11 卡位通风口</b>（传感器按入后盖背面，探头略突出）。<br/>
-      已去掉旁边多余的大“格子”（旧版支脚块 / 外挂仓）。
+      v1.1：外轮廓圆角 + 长边四侧悬臂卡扣合盖；后盖中心微凸是 <b>DHT11 卡位通风口</b>。<br/>
+      已去掉旁边多余的大“格子”。旧无卡扣版见标签 <code>v1.0-case-closed</code>。
    </p>
    <div id="status">加载中…</div>
  </div>
@@ -231,7 +231,8 @@

        root.add(backG); root.add(frontG); root.add(dhtG);
        setLid(0); setExp(0); fit();
-        msg(`合盖对齐已按 mate.json · 外壳 ${mate.outer_l}×${mate.outer_w} mm · DHT 突出 ${mate.dht_proud} mm`);
+        const ver = mate.version ? ` · ${mate.version}` : "";
+        msg(`合盖对齐已按 mate.json${ver} · 外壳 ${mate.outer_l}×${mate.outer_w} mm · R${mate.corner_r ?? "?"} · DHT 突出 ${mate.dht_proud} mm`);
      } catch (e) {
        console.error(e);
        msg("加载失败：请用 python -m http.server 8765 --directory cad", true);