ANSI B17.1 · square key
1/8″ square key and keyseat
The 1/8″ 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 its DIN 6885 neighbours.
A 1/8″ square key fits shafts over 0.4375″ (7/16″) through 0.5625″ (9/16″) under ANSI B17.1. The shaft keyseat is 0.125″ wide, matching the key, and 0.0704″ is the cut depth the configurator uses for it. 2 standard fractional diameters fall in that range: 1/2″, 9/16″.
No NEMA frame in our catalog carries this key: the smallest keyed NEMA shaft we list is 0.625″ (frame 56), which takes a 3/16″ key.
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.
1/8″ square key and keyseat
| Shaft Ø range (in) | Square key (in) | Keyseat width (in) | Keyseat depth (in) |
|---|---|---|---|
| over 0.4375 to 0.5625 (over 7/16 to 9/16) | 1/8 sq | 0.125 | 0.0704 |
| Standard shaft diameters in this range (1/16″ steps) | 1/2″, 9/16″ | ||
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.
Metric neighbours (DIN 6885)
| DIN 6885 key (b × h) | Shaft Ø range (mm) | Shaft Ø range (in) | Keyseat width (in) | Keyseat depth (in) |
|---|---|---|---|---|
| 4 × 4 mm | over 10 to 12 | over 0.3937 to 0.4724 | 0.1575 | 0.112 |
| 5 × 5 mm | over 12 to 17 | over 0.4724 to 0.6693 | 0.1969 | 0.1329 |
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 · 3/16 sq · 1/4 sq · 5/16 sq · 3/8 sq · 1/2 sq · 5/8 sq · 3/4 sq · 7/8 sq · 1 sq.
Keyseat length for a 1/8″ 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 0.656″ to 0.844″ across this key's shaft range.
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.