Cost, Tolerances & Reference

Keyway Depth & Key Dimensions Calculator

machining 304 stainless steel speeds and feeds. Get instant Key Width (mm), Key Height (mm), Keyway Depth (mm) for your machining parameters.

Input Parameters

Results

Key Width (mm)β€”
Key Height (mm)β€”
Keyway Depth (mm)β€”
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From the Shop Floor

Monday morning, 7:42 AM. The Mazak spindle is warming up and the first job of the day is on the table β€” 200 pieces of 304 stainless, tolerance Β±0.025mm. The programmer had used a generic Keyway Depth from a free app, but the tooling rep from Dormer Pramet had stopped by Friday with updated chip load charts. The difference? A 22% reduction in cycle time and zero tool changes across the run.

This is the kind of story that plays out in job shops every day. The machinist who trusts the numbers from a reliable Keyway Depth goes home on time. The one who guesses gets to explain to the owner why a $180 GΓΌhring end mill is now a paperweight.

Before (Guessing)
14.2 min/part
3 tool changes per shift
After (Calculated)
11.1 min/part
0 tool changes per shift

The key insight here isn't complicated math β€” it's that Keyway Depth bridges the gap between the ideal conditions in Dormer Pramet's lab in Sandviken and the reality of a shop floor in Shenzhen or Stuttgart. Your Mazak or Starrag only performs as well as the numbers you feed it.

Keyway and key dimension formulas

Keyways transmit torque between shafts and hubs via a square or rectangular key. The keyway dimensions are standardised based on shaft diameter. This calculator provides approximate key and keyway sizes for common shaft diameters.

Frequently asked questions

What is the difference between a keyway and a keyseat?

The keyway is the slot in the hub (gear, pulley). The keyseat is the slot in the shaft. Together they house the key, which prevents relative rotation. The depth of each is approximately half the key height.

What material is used for machine keys?

Cold-drawn low-carbon steel (C1018-C1045) is standard. For high-torque applications, use alloy steel (4140, 4340) hardened to 28-32 HRC. Stainless keys (304, 316) are used in corrosive environments. The key should be slightly softer than the shaft to be the sacrificial wear component.

Key vs spline -- when should I use each?

Keys are simpler and cheaper for low-to-medium torque (under ~500 Nm on a 50 mm shaft). Splines handle higher torque, allow axial sliding, and provide better concentricity. Use splines for automotive transmissions, aircraft actuators, and high-speed rotating assemblies.

How to use this Keyway Depth & Key Dimensions Calculator

Enter the shaft diameter. The calculator suggests standard key width, key height, and keyway depth based on common ISO/ANSI proportions. Always verify against your specific standard (DIN 6885, ANSI B17.1, JIS B1301) for critical applications.

Common mistakes to avoid

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