5/16" Keys | McMaster-Carr

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	System of Measurement System of Measurement

Inch

	Width Width	Show

5/16"

	Width Width	Hide

	Overall Length Overall Length

	Material Material

1008-1045
Carbon Steel

	Height Height

	Key Type Key Type


Straight	Woodruff

Tapered

	Tolerance Rating Tolerance Rating

Undersized

Oversized

Standard

	For Keyway Diameter For Keyway Diameter

	Minimum Hardness Minimum Hardness

	RoHS (Restriction of Hazardous Substances) RoHS (Restriction of Hazardous Substances)

RoHS Compliant

	REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) REACH (Registration, Evaluation, Authorization and Restriction of Chemicals)

REACH Compliant

	Key Number Key Number

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

DFARS Specialty Metals
Compliant

	Specifications Met Specifications Met

ANSI B17.1 Class 1

ANSI B17.2

ANSI B17.1 Class 2

	For Maximum Keyway Diameter Tolerance For Maximum Keyway Diameter Tolerance

0.000"

	For Minimum Keyway Diameter Tolerance For Minimum Keyway Diameter Tolerance

-0.010"

	Finish Finish

Zinc Plated

	End Height End Height

	For Mounting Screw Size For Mounting Screw Size

No. 4

	Rate of Taper Rate of Taper

1/8" per 12"

	For Machine Table T-Slot Width For Machine Table T-Slot Width

5/16"

	Head Length Head Length

7/16"

	Head Height Head Height

1/2"

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54 Products

Machine Keys

Steel keys offer good strength.

18-8 stainless steel keys offer a balance of strength and corrosion resistance. They may be mildly magnetic.

Slightly smaller than the size listed in the table, undersized keys are the choice when you need a slightly looser fit or when you have an inconsistent keyway. Use them when parts need to be taken apart frequently, such as for maintenance or prototyping.

Keys that meet ANSI B17.1 specifications conform to ANSI standards for dimensions and tolerances.

For technical drawings and 3-D models, click on a part number.

		Tolerance
Lg.	Tolerance Rating	Ht.	Wd.	Minimum Hardness	Specifications Met	Pkg. Qty.		Pkg.
1008-1045 Carbon Steel
5/16" × 5/16"
1 1/4"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	ANSI B17.1 Class 1	10	000000000	00000
1 1/2"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	ANSI B17.1 Class 1	10	000000000	0000
2"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	ANSI B17.1 Class 1	10	000000000	00000
2 1/2"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	ANSI B17.1 Class 1	10	000000000	00000
18-8 Stainless Steel
5/16" × 5/16"
1 1/4"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B97	__	5	000000000	0000
1 1/2"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B97	__	5	000000000	00000
2"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B97	__	5	000000000	00000
2 1/2"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B97	__	5	000000000	00000

Woodruff Keys

Side View

Woodruff keys work well near shaft shoulders, where a standard open keyway would create too much stress. They are also often used on tapered shafts. These keys have a rounded shape that makes them easy to remove when parts need to be taken apart frequently, such as for maintenance or prototyping. Because they're usually shorter than standard machine keys, they work best in light duty applications. Use them to connect gears and other components to shafts. Also known as half moon keys.

Steel keys offer good strength.

Inch keys conform to ANSI B17.2 standards for dimensions and tolerances.

For technical drawings and 3-D models, click on a part number.

					Tolerance
Key Number	Wd.	For Keyway Dia.	Ht.	Lg.	Wd.	Ht.	Specifications Met	Pkg. Qty.		Pkg.
1018-1045 Carbon Steel
23	5/16"	1 3/8"	0.584"	1.362"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	000000
25	5/16"	1 1/2"	0.631"	1.484"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	00000
B	5/16"	1"	0.428"	0.992"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	25	000000000	00000
C	5/16"	1 1/8"	0.475"	1.114"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	25	000000000	00000
D	5/16"	1 1/4"	0.537"	1.24"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	00000
8630 Alloy Steel
23	5/16"	1 3/8"	0.584"	1.362"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	00000
25	5/16"	1 1/2"	0.631"	1.484"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	00000
B	5/16"	1"	0.428"	0.992"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	0000
C	5/16"	1 1/8"	0.475"	1.114"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	0000
D	5/16"	1 1/4"	0.537"	1.24"	0.000" to 0.001"	-0.006" to 0.000"	ANSI B17.2	10	000000000	00000

Tapered Gib Keys

These keys have a tapered body that wedges in to the keyway for a more secure fit than standard machine keys. The gib head makes these keys easy to remove when parts need to be taken apart frequently, such as for maintenance or prototyping. Keys are tapered along their length. Use them to connect gears and other components with tapered keyways to shafts. Keys are made of steel.

The height of inch keys decreases by 1/8" for every 12" of length. They conform to ANSI B17.1 Class 1 standards for dimensions and tolerances.

For technical drawings and 3-D models, click on a part number.

	Tolerance		Head
Lg.	Ht.	Wd.	Ht.	Lg.	End Ht.	Rate of Taper	Specifications Met		Each
1018-1045 Carbon Steel
5/16" × 5/16"
2"	-0.002" to 0.000"	-0.002" to 0.000"	1/2"	7/16"	0.295"	1/8" per 12"	ANSI B17.1 Class 1	000000000	00000
2 1/2"	-0.002" to 0.000"	-0.002" to 0.000"	1/2"	7/16"	0.290"	1/8" per 12"	ANSI B17.1 Class 1	000000000	0000
3"	-0.002" to 0.000"	-0.002" to 0.000"	1/2"	7/16"	0.285"	1/8" per 12"	ANSI B17.1 Class 1	000000000	0000
4"	-0.002" to 0.000"	-0.002" to 0.000"	1/2"	7/16"	0.274"	1/8" per 12"	ANSI B17.1 Class 1	000000000	0000

Machine Key Stock

Cut this square or rectangular key stock to length to create a straight machine key. Straight keys are the most common type of key. Machine keys are often the same material and as hard or harder than the shaft and other components with which they are used. To use a key as a sacrificial part, choose a softer key that will shear off when parts are exposed to excessive force, preventing damage to expensive equipment.

Steel key stock is an economical choice with good strength. 8630 alloy steel key stock meets ANSI B17.1 class 2 specifications for dimensions and tolerances. Zinc-plated steel key stock resists corrosion in wet environments.

Stainless steel key stock is more corrosion resistant than steel key stock. 18-8 stainless steel key stock offers a balance of strength and corrosion resistance. It may be mildly magnetic. 316 stainless steel key stock has the best corrosion resistance of our stainless steel key stock and may be mildly magnetic. 416 stainless steel key stock is stronger than other stainless key stock, and can be heat treated for extra strength. It's corrosion resistant and magnetic.

Brass key stock is corrosion resistant and nonmagnetic. Brass is softer than other metals, so it's often used for shear keys.

Aluminum key stock is one-third the weight of steel key stock, but not as strong. It resists corrosion and is nonmagnetic.

Acetal plastic and nylon 6/6 plastic key stock are slippery and wear resistant.

Slightly larger than the size listed in the table, oversized stock fits tightly in a keyway. Press it into place for use in high-torque applications or to replace a key in a worn keyway. Slightly smaller than the size listed in the table, undersized stock is the choice when you need a slightly looser fit or when you have an inconsistent keyway. Use it when parts need to be taken apart frequently, such as for maintenance or prototyping.

For technical drawings and 3-D models, click on a part number.

1018-1045 Carbon Steel

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
1/4" × 5/16"	Oversized	0.000" to 0.003"	0.000" to 0.003"	Rockwell B50	000000000	00000
1/4" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B50	000000000	0000
5/16" × 5/16"	Oversized	0.000" to 0.002"	0.000" to 0.002"	Rockwell B50	000000000	0000
5/16" × 5/16"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	000000000	0000
36" Lg.
5/16" × 5/16"	Oversized	0.000" to 0.002"	0.000" to 0.002"	Rockwell B50	000000000	0000
5/16" × 5/16"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	000000000	0000
72" Lg.
5/16" × 5/16"	Oversized	0.000" to 0.002"	0.000" to 0.002"	Rockwell B50	000000000	00000

1095 Spring Steel

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
1/4" × 5/16"	Standard	-0.001" to 0.001"	-0.001" to 0.001"	Rockwell B90	000000000	000000
5/16" × 5/16"	Standard	-0.001" to 0.001"	-0.001" to 0.001"	Rockwell B90	000000000	0000
36" Lg.
5/16" × 5/16"	Standard	-0.001" to 0.001"	-0.001" to 0.001"	Rockwell B90	000000000	00000

8630 Alloy Steel

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness	Specifications Met		Each
12" Lg.
5/16" × 5/16"	Oversized	0.000" to 0.001"	0.000" to 0.001"	Rockwell B50	ANSI B17.1 Class 2	000000000	00000

Zinc-Plated 1018-1045 Carbon Steel

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
3/16" × 5/16"	Oversized	0.000" to 0.003"	0.000" to 0.003"	Rockwell B50	000000000	00000
3/16" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B50	000000000	0000
1/4" × 5/16"	Oversized	0.000" to 0.003"	0.000" to 0.003"	Rockwell B50	000000000	0000
1/4" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B50	000000000	0000
5/16" × 5/16"	Oversized	0.000" to 0.002"	0.000" to 0.002"	Rockwell B50	000000000	0000
5/16" × 5/16"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	000000000	0000
36" Lg.
5/16" × 5/16"	Oversized	0.000" to 0.002"	0.000" to 0.002"	Rockwell B50	000000000	0000
5/16" × 5/16"	Undersized	-0.002" to 0.000"	-0.002" to 0.000"	Rockwell B50	000000000	0000

18-8 Stainless Steel

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
5/16" × 5/16"	Oversized	0.000" to 0.003"	0.000" to 0.003"	Rockwell B82	000000000	00000
5/16" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B82	000000000	00000
36" Lg.
5/16" × 5/16"	Oversized	0.000" to 0.003"	0.000" to 0.003"	Rockwell B82	000000000	00000
5/16" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B82	000000000	00000

316 Stainless Steel

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
1/4" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B86	000000000	000000
5/16" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B86	000000000	00000
36" Lg.
5/16" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B86	000000000	00000

416 Stainless Steel

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
5/16" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Rockwell B86	000000000	000000

360 Brass

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
5/16" × 5/16"	Standard	-0.003" to 0.003"	-0.003" to 0.003"	Rockwell B35	000000000	000000
36" Lg.
5/16" × 5/16"	Standard	-0.004" to 0.004"	-0.004" to 0.004"	Rockwell B35	000000000	00000

6061 Aluminum

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
5/16" × 5/16"	Standard	-0.008" to 0.008"	-0.008" to 0.008"	Rockwell B95	000000000	000000

Nylon 6/6 Plastic

		Tolerance
Ht. × Wd.	Tolerance Rating	Ht.	Wd.	Minimum Hardness		Each
12" Lg.
5/16" × 5/16"	Undersized	-0.003" to 0.000"	-0.003" to 0.000"	Durometer 80D	000000000	000000

Fixture Keys

Rectangular

Sized to fit with precision in machine table T-slots, use these keys to locate fixtures and vises on your machine table. They mount to the underside of your fixture or vise with a socket head cap screw.

For technical drawings and 3-D models, click on a part number.

Inch

Rectangular
For Machine Table T-Slot Wd.	Lg.	Wd.	Ht.	Wd. Tolerance	For Mounting Screw Size	Mounting Fasteners Included	Material		Each
5/16"	3/4"	5/16"	1/2"	-0.0005" to 0"	No. 4	No	Steel	0000000	00000