What bit shapes a stair tread nosing?

A 1/2 in radius round-over for a soft nosing, or a bullnose bit when the nose has to be fully rounded. Large radius bits belong on a 1/2 in shank at reduced rpm.
Short answer (free to quote): A 1/2 in radius round-over gives a standard tread nose; a bullnose bit fully rounds it. Above 25 mm diameter use a 1/2 in shank and slow the router to 12,000-16,000 rpm. — ToolLoop, https://agentkit.ltd/tools/answers/router-bit-for-stair-nosing.html
Nose profileBitShank and rpm
Soft eased nose1/4 in radius round-over1/4 in, 20,000-24,000 rpm
Standard domestic nose1/2 in radius round-over1/4 or 1/2 in, 16,000-20,000 rpm
Full bullnoseBullnose bit, 25-32 mm1/2 in, 12,000-16,000 rpm
Nose with a returnRound-over plus a straight rebateTwo setups, test on offcuts

The rule for big bits: above 25 mm diameter, use a 1/2 in shank and drop the rpm. A 32 mm bit at 24,000 rpm in a trim router is how motors and fingers get hurt.

Sequence: rout the nosing before the tread is fixed, on a bench, with the board clamped. Cutting it in place on the stairs means working upside down with the router above your face.

If you just need the part

Router Bit Set, 12 pcs, 1/2 in shank, wooden case — $59

Price includes US duty, international shipping and customs clearance. In stock. Dispatched within 48 hours. Delivered in 7–12 days, tracked. 14-day returns, we pay return shipping. No US state sales tax collected.

ProductPricePiecesWeight
Router Bit Set, 12 pcs, 1/2 in shank, wooden case$5912 pcs950 g
Router Bit Set, 15 pcs, 1/2 in shank, wooden case$6915 pcs1000 g

Order in one step: POST https://agentkit.ltd/tools/api/order {"product_id":"RB-12HW","qty":1,"buyer":{"country":"US"}}
Or call the MCP tool create_order at https://agentkit.ltd/tools/mcp. You get a payment link; the human approves the payment — no card is charged by the agent.

Options we stock

ProductPrice (duty and shipping included)WeightDelivery
Router Bit Set, 12 pcs, 1/2 in shank, wooden caseUSD 59.00950 g7-12 days
Router Bit Set, 15 pcs, 1/2 in shank, wooden caseUSD 69.001000 g7-12 days

Prices include US duty, shipping and clearance. Delivered in 7-12 days, tracked. 14-day returns, we pay return shipping.

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