Parametric U-Shape Generator (OpenSCAD · mm)

Flexibly create U-shaped holders, brackets, and inserts – fully parametric, precise to the millimeter, and MakerWorld-safe.
Supports round holes and slots, oval counterbores & countersinks for slots, countersink/counterbore for round holes, per-corner radii, outer chamfers (top/bottom), inner top chamfer, hole arrays, per-side inset, and a groove mode for mating parts

Compatibility: OpenSCAD Customizer, dimensions in mm, only basic body CSG (no offset(), hull(), scale(), assert())

Highlights

• Scalable: Outer dimensions, U-geometry (leg/thickness, bottom, gap) freely selectable
• Clean Edges: per-corner roundings (inner/outer), outer chamfers (stepped)
• Pro Holes: Round or Slot (capsule) with Counterbore or Countersink
• Oval Slot Head: flat Counterbore or stepped Countersink without scale()
• Flexible Placement: Hole insets per side, vertical arrays (count & pitch)
• Inner Top Chamfer: softens edge on upper inner frame
• Groove Mode: generates positive mating part (e.g., milling groove) with selectable clearance
• UX Extras: Anchor options, optional debug guides, echo summary with warnings
• MakerWorld-safe: pure CSG construction, robust parameter clamps

Parameter Overview (Short)

Size & U-Geometry

• outer_width_mm, outer_height_mm, part_height_mm
• leg_thickness_mm (or asymmetric left/right)
• gap_width_mm (gap/inner width), bottom_thickness_mm

Roundings & Chamfers

• Outer: outer_corner_rounding_enable (+ per-Corner optional)
• Inner: inner_corner_rounding_enable (+ per-Corner optional)
• Outer Chamfers top/bottom: top_chamfer_*, bot_chamfer_* (stepped)
• Inner Top Chamfer: inner_top_chamfer_* (stepped)

Holes & Slots

• Shape: hole_shape__0_round__1_slot
• Round: hole_diameter_mm
• Slot: hole_diameter_mm (Minor), slot_length_mm (total length)
• Head (Round & Slot): hole_head_type__0_none__1_counterbore__2_countersink
• Head Dimensions: hole_head_diameter_mm, hole_head_depth_mm
• Slot Head additionally: slot_head_length_mm, slot_sink_steps (fineness for Countersink)

Placement & Arrays

• Inset: hole_inset_mode__0_single__1_per_side, hole_inset_mm or Left/Right
• Vertical: holes_count_per_leg, holes_pitch_z_mm, hole_top_margin_mm

Groove

• output_mode__0_Part__1_Groove
• groove_clearance_enable, groove_clearance_mm

UX

• Anchor: anchor__0_center__1_bottom_front_left__2_bottom_center
• Debug: debug_guides_enable (preview only)
• Console Info: echo_summary_enable
• Resolution: $fn = $preview ? 24 : 48

Common Setups (mm)

• M3 Mount (round, Counterbore)
  • hole_shape=0 · hole_diameter=3.2 · head_type=1 · head_D=6 · head_depth=2
  • holes_count=1 · hole_inset=2 · top_margin=4
  • outer_w=30 · outer_h=20 · gap=10 · leg=3 · bottom=4 · part_h=10
• M4 Mount (round, Counterbore)
  • hole_shape=0 · hole_diameter=4.3 · head_type=1 · head_D=8 · head_depth=2.5
  • holes_count=1 · hole_inset=2 · top_margin=4
  • outer_w=36 · outer_h=22 · gap=12 · leg=3.5 · bottom=4 · part_h=12
• Zip-Tie Slots (oval, flat head)
  • hole_shape=1 · hole_diameter=5.2 · slot_length=12
  • head_type=1 · slot_head_length=14 · head_D=6 · head_depth=1.5
  • holes_count=2 · pitch_z=6 · top_margin=5
  • outer_w=40 · outer_h=22 · gap=12 · leg=3 · bottom=4 · part_h=10
• M3 Countersink (round, countersunk)
  • hole_shape=0 · hole_diameter=3.2 · head_type=2 · head_D=6 · head_depth=1.8
• Groove/Mating Part (with tolerance)
  • output_mode=1 · groove_clearance_enable=1 · groove_clearance=0.2
  • Holes off (add_holes_enable=0)

Recommended Edge Settings

• Outer radii: outer_*_enable=1, radius=2.0 (optionally per-Corner)
• Inner radii: inner_*_enable=1, radius=1.5
• Outer Chamfers (visually clean, fast to render):
  • top/bot_enable=1 · depth=1.0 · inset=1.0 · steps=3
• Inner Top Chamfer (grippier, deburred):
  • enable=1 · depth=0.8 · inset=0.6 · steps=3

Sanity Check (Prevents Failures)

• Hole Inset ≤ Leg Width – Ø/2 – 0.2 mm.
  (Our clamps catch this; if "too large", holes automatically shift inward.)
• Top Margin ≥ Ø/2 + 0.2 mm.
• Countersink/Counterbore Head Ø ≥ Hole Ø.
• Slot Head Length ≥ Slot Length.
• Chamfer Depths: top_depth + bot_depth < part_height.

Print Notes (short & pragmatic)

• FDM: 0.2 mm layer, 3–4 perimeters, 20–30% infill; small countersinks optionally with 0.16 mm layer.
• Resin: Clean countersinks, but note minimum wall thicknesses (≥1.2–1.5 mm).