Parametric Drum Shell with Independent Keller-Style Bearing Edges, Lug Mounting Holes, and Optional Recessed Finishes

Units used by OpenSCAD geometry: millimeters

Nominal shell diameter / commercial drumhead size in inches: 8,10,12,13,14,15,16
 

User-facing dimensions:

- shell_diameter_in is the nominal drum/head size in inches

- the modeled outer diameter is automatically undersized by head_clearance_inches

- shell_depth_in is in inches

- Keller shell wall thickness is selected by ply count and applied in millimeters

Edge profiles:

- Top and bottom edges are independently selectable.

- Rounded preserves the original rounded outer-edge design.

- Inner Chamfer uses a Keller-style 45-degree inner cut, an apex near the exterior, and a small outer counter-cut.

Lug hole logic:

- Lugs are evenly spaced by 360 / active_lug_count.

- Top only or top and bottom lugs.

- Each lug has two vertically spaced screw holes.

- Hole cylinders drill radially outward through the shell wall.

- Hole radius automatically follows the selected shell diameter and shell thickness.

Finish logic:

- Default finish is None and adds no extra texture or geometry.

- Optional finishes are shallow recessed patterns cut into the exterior only.

- Dimple finish uses shallow spherical-cap cuts for concave circles rather than flat cylindrical pockets.