Hand Kinematics Bench

Every slider is bounded by measured human limits. You cannot build an impossible hand here.

Subject size

Hand length

Hand breadth

Digit proportions

× nominal ratio

Pose

custom

All fingers · MCP flex

All fingers · PIP flex

Fan / spread

Biomechanical constraints

Couple DIP to PIP — DIP ≈ 0.67 × PIP. The terminal extensor makes the DIP a dependent joint; most gloves infer it rather than sense it. Abduction collapses with flexion — collateral ligaments tighten over the metacarpal head, so spread authority falls to zero by 90° MCP flexion. Juncturae tendinum — linked extensors stop adjacent fingers flexing more than ~25–30° apart.

clearance mm

Pose copied to the clipboard. Save it as pose.json next to hand_export.py, then build the STEP:

python3 hand_export.py --pose-file pose.json --clearance 2

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Hand Bench

Subject size

Digit proportions

Pose

Biomechanical constraints