Set of 5 brass clock winding keys covering the odd sizes 3, 5, 7, 9 and 11 — the sizes most commonly needed for barrel and fusee clock winding squares.
⭐ At a glance
📏 5 keys, sizes 3–11 (odd numbers only)
✅ Covers winding squares from 3mm to 5mm
📦 Set of 5 keys included
✔️ New, brass construction
🔧 What it does & how to use
A clock winding key fits over the square winding arbor on the clock movement and is turned to tension the mainspring that powers the clock. Each numbered size corresponds to a different arbor width, so having a run of sizes means you can match the key to the clock without forcing or slipping.
- Identify the arbor: look at the square winding post on the clock face or through the winding hole in the case back.
- Match the size: try the keys in order — Number 3 (3mm), Number 5 (3.5mm), Number 7 (4mm), Number 9 (4.5mm), Number 11 (5mm) — until you find one that seats fully and squarely without play.
- Wind gently: turn in the correct direction (usually clockwise) with steady, even pressure — never force the key if it feels resistant.
- Stop at full tension: ease off once the mainspring feels firm; overwinding can damage the movement.
⚠️ Please check the winding square size on your clock before buying — a key that's too loose or too tight can slip or strain the arbor. This set covers odd sizes 3–11 only; even sizes and full odd-and-even sets are sold separately.
