[family-assembly] cabinet_bar_pull_handle: cabinet/drawer bar pull

designs/cabinet_bar_pull_handle/family.json

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+{
+  "family": "cabinet_bar_pull_handle",
+  "standard": "Berenson SS bar-pull series (7068-7072) / Richelieu BP305",
+  "base_plane": "XY",
+  "description": "Cabinet/drawer bar pull as a simple assembly: a straight round bar and two standoff posts as three separate solids, each post coped to seat against the bar and tapped from the base for the mounting screw; bar ends optionally chamfered.",
+  "source": "Berenson 7068-7072 + Richelieu BP305 dimensioned drawings (C-C, overall length, bar/post diameter, projection, tap); bar/post/projection cross-checked constant across Amerock + Hickory",
+  "contributor": "BenchCAD-org",
+  "solids": 3
+}

designs/cabinet_bar_pull_handle/part.py

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+"""cabinet_bar_pull_handle — the parametric part (simple assembly, solids=3).
+
+A cabinet/drawer bar pull as the three parts it is assembled from: a straight
+round bar, and two cylindrical standoff posts that carry it off the cabinet
+face, each post tapped from the base for the mounting machine screw. The post
+tops are coped (saddle-cut by the bar cylinder) so each post mates flush against
+the bar's underside with zero interpenetration — the members stay three separate
+solids, as assembled. The bar overhangs each post; its ends are optionally
+chamfered. The cabinet face is z=0; posts stand up +Z, the bar runs along X.
+
+Interface + examples: docs/DESIGN_SPEC.md
+"""
+
+import cadquery as cq
+
+
+def build(center_to_center, overhang, projection, bar_d, post_d, tap_d, tap_depth, chamfer_ends):
+    length = center_to_center + 2.0 * overhang  # overall bar length
+
+    # projection is the standoff to the bar's OUTER face, so the bar axis sits
+    # half a bar-diameter below it
+    z_bar = projection - bar_d / 2.0
+
+    # round bar across the posts (along X), its axis at z_bar — one solid
+    bar = cq.Workplane("YZ").circle(bar_d / 2.0).extrude(length).translate((-length / 2.0, 0.0, z_bar))
+    if chamfer_ends:
+        bar = bar.faces(">X").chamfer(bar_d * 0.1)
+        bar = bar.faces("<X").chamfer(bar_d * 0.1)
+
+    # an uncut, unchamfered bar cylinder as the coping tool, so the post saddle
+    # follows the bar surface even at a chamfered end
+    bar_tool = (
+        cq.Workplane("YZ").circle(bar_d / 2.0).extrude(length).translate((-length / 2.0, 0.0, z_bar))
+    )
+
+    # two posts standing off the cabinet face, each tapped from the base; each
+    # rises to the bar axis and is coped by the bar so it seats on the underside
+    # without intersecting it — separate solids, in contact only
+    posts = []
+    for sx in (-1.0, 1.0):
+        post = (
+            cq.Workplane("XY")
+            .circle(post_d / 2.0)
+            .extrude(z_bar)
+            .translate((sx * center_to_center / 2.0, 0.0, 0.0))
+        )
+        post = post.faces("<Z").workplane(centerOption="CenterOfBoundBox").hole(tap_d, depth=tap_depth)
+        post = post.cut(bar_tool)
+        posts.append(post)
+
+    result = cq.Compound.makeCompound([bar.val(), posts[0].val(), posts[1].val()])
+    return result

designs/cabinet_bar_pull_handle/spec.py

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+"""cabinet_bar_pull_handle — the benchmark generator spec.
+
+A cabinet/drawer bar pull (round bar on two standoff posts). PARAM_SPEC declares
+each build() parameter; check() holds the engineering rules a reviewer audits.
+Nothing is coupled, so there is no refine(). Spec: docs/DESIGN_SPEC.md
+
+Sources:
+- Berenson SS hollow bar-pull series (7068-7072) + Richelieu BP305 line: bar
+  Ø12 mm, post Ø10 mm, projection 32.5-35 mm, center-to-center 76-638 mm, mount
+  tapped 8-32 / M4. Overall length = C-C + ~2*overhang.
+- Bar Ø / post Ø / projection cross-checked constant across Berenson, Amerock,
+  Hickory; C-C is the catalog ladder (96/128/160/192/224/320 mm). Within one
+  line only C-C + length vary, so bar Ø / post Ø / projection are "proportion".
+"""
+
+
+# ── 1. PARAM_SPEC ────────────────────────────────────────────────────────────
+PARAM_SPEC = {
+    "center_to_center": dict(
+        desc="center-to-center spacing of the two mounting posts",
+        unit="mm",
+        range={"easy": (96.0, 192.0), "medium": (76.0, 320.0), "hard": (76.0, 638.0)},
+        source="Berenson 7068-7072 / Richelieu BP305 C-C ladder (76-638 mm)",
+        askable=True,
+    ),
+    "overhang": dict(
+        desc="bar overhang past each post (overall length = C-C + 2*overhang)",
+        unit="mm",
+        range={"easy": (24.0, 40.0), "medium": (20.0, 50.0), "hard": (18.0, 60.0)},
+        source="Richelieu overhang ~40 mm; Berenson ~24 mm -> proportion",
+        askable=True,
+    ),
+    "projection": dict(
+        desc="standoff height (how far the bar stands off the cabinet face)",
+        unit="mm",
+        range={"easy": (32.0, 35.0), "medium": (28.0, 38.0), "hard": (25.0, 42.0)},
+        source="Berenson 32.5 mm / Amerock 35 mm / Hickory 32 mm",
+        askable=True,
+    ),
+    "bar_d": dict(
+        desc="handle bar diameter",
+        unit="mm",
+        range={"easy": (11.0, 13.0), "medium": (10.0, 16.0), "hard": (9.0, 16.0)},
+        source="Berenson/Amerock/Hickory Ø12 mm (1/2 in) -> proportion across lines",
+        askable=True,
+    ),
+    "post_d": dict(
+        desc="standoff-post diameter",
+        unit="mm",
+        range={"easy": (9.0, 11.0), "medium": (8.0, 12.0), "hard": (7.0, 13.0)},
+        source="Berenson Ø10 mm / Amerock 3/8 in (9.5 mm) -> proportion",
+        askable=True,
+    ),
+    "tap_d": dict(
+        desc="mounting-screw tap hole diameter (in the post base)",
+        unit="mm",
+        range={"easy": (3.2, 3.6), "medium": (3.0, 4.5), "hard": (2.5, 5.0)},
+        source="8-32 / M4 tap (Berenson M4; Richelieu 8-32)",
+        askable=True,
+    ),
+    "tap_depth": dict(
+        desc="tap-hole depth into the post",
+        unit="mm",
+        range={"easy": (5.0, 7.0), "medium": (4.0, 10.0), "hard": (4.0, 12.0)},
+        source="Richelieu 8-32 x 6 mm deep -> proportion",
+        askable=True,
+    ),
+    "chamfer_ends": dict(
+        desc="bar ends chamfered (1) vs square (0)",
+        unit="",
+        range={"easy": (0, 0), "medium": (0, 1), "hard": (0, 1)},
+        source="Richelieu bar ends C1.2x45 chamfer",
+        choices={"easy": [0], "medium": [0, 1], "hard": [0, 1]},
+        feature=True,
+    ),
+}
+
+
+# ── 2. check ─────────────────────────────────────────────────────────────────
+def check(p: dict) -> list[str]:
+    """Engineering constraints (empty = valid). Each cites its rule."""
+    bad = []
+
+    # finger clearance under the bar (projection is to the bar's outer face, so
+    # the clear gap below the bar is projection - bar_d)
+    if p["projection"] - p["bar_d"] < 8.0:
+        bad.append("projection - bar_d < 8: too little finger clearance under the bar")
+
+    # the mounting tap must fit within the post (post rises to z = projection - bar_d/2)
+    if p["tap_depth"] > p["projection"] - p["bar_d"] / 2.0 - 2.0:
+        bad.append("tap_depth exceeds the post height (projection - bar_d/2 - 2): tap would break through")
+
+    # the tap hole must leave a post wall
+    if p["tap_d"] > p["post_d"] - 2.5:
+        bad.append("tap_d > post_d-2.5: tap leaves <1.25 mm post wall")
+
+    # posts must be clearly separated
+    if p["center_to_center"] < p["post_d"] + 8.0:
+        bad.append("center_to_center < post_d+8: posts too close / overlapping")
+
+    # the bar must actually overhang the posts
+    if p["overhang"] < p["bar_d"]:
+        bad.append("overhang < bar_d: bar ends barely clear the posts")
+
+    return bad