KEVOS® MAKEOS · Power Transmission
Keyseat Depth and Measurement over Key
What depths should be measured when cutting this keyseat in a round shaft?
Chordal height at the keyseat edge, keyseat depth at the shaft centre-line, the measurement from the bottom of the keyseat to the opposite side of the shaft, and from the top of the key to the opposite side.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Shaft diameter | mm or in | Shaft diameter at the keyseat. |
| Key width | mm or in | Width of the key (and keyseat). |
| Keyseat depth at the side (from the edge) | mm or in | Depth of the keyseat measured at its side wall (from the key standard, e.g. t₁ in ISO or half the key height for square keys). |
| Key height | mm or in | Height of the key. |
Method and formulas
- Chordal height Y = (D − √(D² − w²)) ÷ 2.
- Depth at centre-line = Y + t.
- S = D − Y − t (micrometer over the shaft from the keyseat floor); T = S + h (over the fitted key).
- Example: a 12 mm keyseat 5 mm deep in a 40 mm shaft measures 34.079 mm from its floor across the shaft.
Limitations
- Flat-bottomed keyseat; Woodruff keyseats are circular and have their own tables.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Set the cutter depth when milling a keyseat
- Inspect keyseat depth with a micrometer over the shaft
- Check the key projection
Who it is for
- Machinists
- Quality inspectors
- Maintenance fitters
What you get
- Chordal height
- Depth at the centre-line
- Bottom of keyseat to opposite side of shaft
- Top of key to opposite side of shaft
Interpreting the result
- Measure S with a micrometer across the shaft to the keyseat floor.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 2460–2486. Topic reference; no source tables or recommended settings are reproduced.
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