Taper Keys

The tapered key is tapered only on the side that engages the hub. [cite: 34, 36] The keyway in the hub has a taper that matches that of the tapered key. Some taper keys have a gib, or tab, for easier removal during disassembly.

See our Gib Head Key Dimensional Charts.

The purpose of the taper is to secure the key itself, as well as, to firmly engage the shaft to the hub without the need for a set screw. [cite: 38] The problem with taper keys is that they can cause the center of the shaft rotation to be slightly off of the mating part. It is different from a tapered shaft lock in that tapered keys have a matching taper on the keyway, while tapered shaft locks do not.

Dimensional Charts are for Metric Taper Keyways, Metric Taper Keys, Imperial Taper Keyways and Imperial Taper Keys.

Dimensions shown are in Inches, if you wish to convert to mm, please use our universal converter.

TAPER KEYWAY DIMENSIONS - METRIC - BS 4235-1: 1972

Shaft Dia Over	Shaft Dia Incl	Keyway Width (B)	Shaft Depth (T1)	Hub Depth (T2)
6	8	2	1.2	1
8	10	3	1.8	1.4
10	12	4	2.5	1.8
12	17	5	3	2.3
17	22	6	3.5	2.8
22	30	8	4	3.3
30	38	10	5	3.3
38	44	12	5	3.3

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TAPER KEY DIMENSIONS - METRIC - BS 4235 -1: 1972

Width (W)	Height (H)	Shaft Dia Over	Shaft Dia Incl
2	2	6	8
3	3	8	10
4	4	10	12
5	5	12	17
6	6	17	22
8	7	22	30
10	8	30	38
12	8	38	44

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TAPER KEYWAY DIMENSIONS - IMPERIAL - BS 46:1 1958

Shaft Dia Over	Shaft Dia Incl	Keyway Width (B)	Shaft Depth (T1)	Hub Depth (T2)
0.25	0.3125	0.0938	0.047	0.048
0.3125	0.4375	0.125	0.062	0.064
0.4375	0.5625	0.1563	0.078	0.08
0.5625	0.875	0.1875	0.094	0.096
0.875	1.25	0.25	0.125	0.128

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TAPER KEY DIMENSIONS - IMPERIAL - BS 46:1 1958

Width (W)	Height (H)
0.0938	0.0938
0.125	0.0938
0.1563	0.125
0.1875	0.125
0.25	0.1875