ANSI B17.1 · square key

5/8″ square key and keyseat

The 5/8″ square key's row of the ANSI B17.1 schedule — shaft range, keyseat width and the cut depth the configurator uses — with the standard diameters it covers and the NEMA frames and catalog parts cut with it.

A 5/8″ square key fits shafts over 2.25″ (2-1/4″) through 2.75″ (2-3/4″) under ANSI B17.1. The shaft keyseat is 0.625″ wide, matching the key, and 0.3555″ is the cut depth the configurator uses for it. 8 standard fractional diameters fall in that range: 2-5/16″, 2-3/8″, 2-7/16″, 2-1/2″, 2-9/16″, 2-5/8″, 2-11/16″, 2-3/4″.

6 NEMA frames in our motor-shaft catalog carry this key (364T, 365T, 444TS, 445TS, 447TS, 449TS), on shaft diameters of 2.375″, with keyseat lengths from 3.03″ to 4.28″. 7 other catalog parts use it, across ANSI Pump Shafts, Rigid Flange Coupling Hubs and CEMA Screw-Conveyor Shafts.

Place a keyseat on any diameter in that range in the configurator and it lands on this width and depth automatically; you set the length and where along the shaft it sits, and choose an end or captivated keyseat. The schedule is the default, not a limit: width and depth can be set by hand for a non-standard key, and the configurator notes the departure from the schedule.

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5/8″ square key and keyseat

Inches. Depth is the slot depth cut into the shaft, the value the configurator applies for this key size. The shaft range runs from just over the lower figure through the upper one.

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NEMA frames with a 5/8″ key

Shaft diameter and keyseat length from the NEMA frame data the motor-shaft catalog is built from; each frame links to its part.

Other catalog parts with a 5/8″ key

Keyed Ø is the diameter the slot is cut in; length is the keyseat length on the part.

Metric neighbours (DIN 6885)

DIN 6885 sizes whose shaft range overlaps this key's, as the configurator's metric sizing applies them. The metric schedule breaks at different diameters, so one inch size usually spans two or three DIN sizes.

Part of Keyway and keyseat dimensions. Other pages in the series: 3/32 sq · 1/8 sq · 3/16 sq · 1/4 sq · 5/16 sq · 3/8 sq · 1/2 sq · 3/4 sq · 7/8 sq · 1 sq.

Keyseat length for a 5/8″ key

The schedule fixes width and depth; length is yours to set. The rule of thumb on the main guide — about 1.5 times the shaft diameter — gives 3.375″ to 4.125″ across this key's shaft range. The NEMA frames above specify 3.03″ to 4.28″ (the standard's ES dimension), which is what the catalog parts carry.

Related: All key sizes · Motor shafts · Gearbox shafts · Pump shafts.

Frequently Asked Questions

These references are for specifying a part; every value here is one the configurator applies when you build one. Numbers are representative of the standard; check them against your part and its mating components before ordering. See all guides on the guides page.