Woodruff Key Sizes (Inch Series)
Inch woodruff key ladder by key number (202 through 2825-class): W x B section, bore fit F, key height C max/min and height-above-shaft E — the half-round key size selection table.
Last updated: 2026-11
Specifications
Woodruff keys are the half-round keys that seat in a semicircular shaft slot and level themselves to the hub, and the inch series orders them by key number. The collected chart runs the number ladder from 202 up through the large sections: per key number, the W x B section (width x bore diameter in fractions — 1/16 x 1/4 at key 202 up through 5/16-wide sections on the large numbers), the bore fit F (0.248 at 202 climbing with the bore), key height C max/min pairs (0.109/0.104 upward), and the height-above-shaft E with its max/min split (0.109/0.104 through 1/64 to 3/64 protrusion classes). The key number itself encodes the section — its digits carry the bore and width — which is why the number, not the dimensions, is the ordering identifier. The registered metric identity is DIN 6888; this is the inch ladder that legacy US machinery orders against.
| Series / scope | Inch woodruff keys by key number, 202 upward through the large sections as tabulated (collected page names no standard — identity from the key-number series; DIN 6888 is the metric identity) |
|---|---|
| Section W x B | Width x bore in fractions: 1/16 x 1/4 (202), 1/16 x 5/16 (202.5), 3/32 x 5/16 (302.5), 1/16 x 3/8 (203)... up the ladder as printed |
| Bore fit F | 0.248 (202), 0.311 (202.5), 0.374 (203), 0.491 (204)... climbing with bore as printed |
| Key height C | Max/min pairs: 0.109/0.104 (202) upward — the half-round height |
| Height above shaft E | Max/min pairs with protrusion class 1/64 to larger steps as printed |
| Not tabulated | Keyseat cutter dimensions (the keyseat identity is a separate table), lengths, material/hardness — per RFQ |
Materials
- Woodruff key supply is key steel, typically C1215-class cold drawn; the half-round form is milled from the same stock as parallel keys. Selection is by shaft diameter and hub bore from the number ladder — the W x B section must match the keyseat cutter that cut the slot, because a woodruff slot is semicircular and no shimming fixes a depth mismatch. Order by key number ("woodruff key 406") and confirm the section on receipt; the inch series does not interchange with the metric DIN 6888 numbering even where sections nearly coincide
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (Woodruff Key Sizes (Inch Series)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
What does the key number actually encode?
The section, in the classic inch-woodruff convention: the digits carry the nominal bore and width (a 406 reads as 4/16ths width class over a 6/16ths bore class — the 1/8 x 3/4-class section). That is why maintenance parts systems order by number alone: the number reproduces both dimensions without arithmetic. The chart's W x B and F columns are the verification — match the number to the section before cutting a keyseat, because the cutter and the key must agree exactly and a one-step error in the number is a scrapped shaft at the milling machine, not at the counter.
Why choose a woodruff key over a parallel key?
Self-alignment and depth. The round-bottomed slot lets the key pivot to meet hub keyway misalignment, and the deep semicircular seat resists rolling on inclined shafts — which is why tapered shaft ends and old machine-tool spindles favour them. The costs: the deep slot weakens the shaft more than a parallel seat, load capacity per size is lower, and removal needs the key's protruding height (the E row) to get pliers or a drift under. Use them where the drawing says so; retrofit decisions should weigh the shaft-scarring against the alignment benefit.
Related knowledge
- Thread-Forming vs Thread-Cutting vs Thread-Rolling Self-Tapping Screws: What the Evidence Settles on Base Material
- Screw Family Selection by Base Material: Wood, Machine and Self-Tapping Threads, Engagement and Coating
- Hex Bolts vs Socket Head Cap Screws: What the Evidence Settles on Strength, Clearance and Cost
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support