1/2"-8 Rods | McMaster-Carr

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	System of Measurement System of Measurement

Inch

	Thread Size Thread Size	Show

1/2"-8

	Thread Size Thread Size	Hide

	Thread Type Thread Type

Acme

Rounded Acme

	Material Material

	Component Component

	Lead Screw
	Nut

	Length Length

	Thread Direction Thread Direction


Right Hand	Left Hand

	Number of Thread Starts Number of Thread Starts

	Threading Threading

	Fully Threaded

	Travel Distance per Turn Travel Distance per Turn

0.125"

0.25"

0.5"

	Speed Ratio Speed Ratio

	Nut Type Nut Type


Hex	Flange

Round	Externally Threaded

	Tensile Strength Tensile Strength

	Hardness Hardness

	Thread Fit Thread Fit

Class 2C

Class 2G

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

RoHS Compliant

RoHS Compliant with
Exemptions

	Fastener Strength Grade/Class Fastener Strength Grade/Class

ASTM Grade B7

Grade 2

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

DFARS Specialty Metals
COTS-Exempt

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

REACH Compliant

	Specifications Met Specifications Met

ASTM A108

ASTM A193

	Diameter Diameter

	Width Width

7/8"

	Height Height

31/64"

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52 Products

Selecting Compatible Lead Screws and Nuts

Found in hand-powered clamps, vises, grates, doors, and work tables, lead screws and nuts have broad, square threads that are well suited for quick assembly, high clamping forces, and lifting and lowering heavy objects. To ensure compatibility, please select components that have the same thread direction and size.

Carbon steel components are easier to machine than alloy steel components. Zinc-plated carbon steel components have mild corrosion resistance. Alloy steel components are harder and stronger than carbon steel components. 18-8 stainless steel components have good corrosion resistance.

Travel distance per turn, also known as screw lead, is the distance a nut or handle moves with one revolution of the lead screw.

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

Lead Screws—Right-Hand Threaded

Carbon Steel
Thread Size	Lg.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Fastener Strength Grade/Class	Hardness	Tensile Strength, psi	Specifications Met		Each
1/2"-8	12"	1	1:1	0.125"	Class 2G	Grade 2	Rockwell B61	64,000	ASTM A108	000000000	00000
1/2"-8	3 ft.	1	1:1	0.125"	Class 2G	Grade 2	Rockwell B61	64,000	ASTM A108	000000000	00000
1/2"-8	6 ft.	1	1:1	0.125"	Class 2G	Grade 2	Rockwell B61	64,000	ASTM A108	000000000	00000
Alloy Steel
1/2"-8	12"	1	1:1	0.125"	Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	000000000	00000
1/2"-8	3 ft.	1	1:1	0.125"	Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	000000000	00000
1/2"-8	6 ft.	1	1:1	0.125"	Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	000000000	00000
18-8 Stainless Steel
1/2"-8	12"	1	1:1	0.125"	Class 2G	__	Rockwell B96	Not Rated	__	000000000	00000
1/2"-8	3 ft.	1	1:1	0.125"	Class 2G	__	Rockwell B96	Not Rated	__	000000000	00000
1/2"-8	6 ft.	1	1:1	0.125"	Class 2G	__	Rockwell B96	Not Rated	__	000000000	000000

Lead Screws—Left-Hand Threaded

Carbon Steel
Thread Size	Lg.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Fastener Strength Grade/Class	Hardness	Tensile Strength, psi	Specifications Met		Each
1/2"-8	3 ft.	1	1:1	0.125"	Class 2G	Grade 2	Rockwell B61	64,000	ASTM A108	000000000	000000
1/2"-8	6 ft.	1	1:1	0.125"	Class 2G	Grade 2	Rockwell B61	64,000	ASTM A108	000000000	00000
Alloy Steel
1/2"-8	3 ft.	1	1:1	0.125"	Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	000000000	00000
1/2"-8	6 ft.	1	1:1	0.125"	Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	000000000	00000

Hex Nuts—Right-Hand Threaded

Hex nuts fasten and position lead screw components.

Carbon Steel
Thread Size	Ht.	Wd.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Hardness		Each
1/2"-8	31/64"	7/8"	1	1:1	0.125"	Class 2G	Rockwell B75	000000000	00000
Zinc-Plated Carbon Steel
1/2"-8	31/64"	7/8"	1	1:1	0.125"	Class 2G	Rockwell B75	000000000	00000
18-8 Stainless Steel
1/2"-8	31/64"	7/8"	1	1:1	0.125"	Class 2G	Rockwell B97	000000000	00000

Hex Nuts—Left-Hand Threaded

Hex nuts fasten and position lead screw components.

Carbon Steel
Thread Size	Ht.	Wd.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Fastener Strength Grade/Class	Hardness		Each
1/2"-8	31/64"	7/8"	1	1:1	0.125"	Class 2G	Grade 2	Rockwell B85	000000000	00000
18-8 Stainless Steel
1/2"-8	31/64"	7/8"	1	1:1	0.125"	Class 2G	__	Rockwell B97	000000000	00000

Fast-Travel Precision Acme Lead Screws and Nuts

Multiple thread channels (also known as thread starts) create faster linear travel than lead screws with a single thread start. The threads have a tight thread fit for accurate, repeatable starts and stops. Pair with a motor in automated motion and positioning applications. To ensure compatibility, please select components that have the same thread direction, thread size, and number of thread starts.

Carbon steel lead screws and flanges have good machinability. Black-oxide alloy steel lead screws are hard and strong. They have mild corrosion resistance. 303 and 304 stainless steel lead screws and flanges have good corrosion resistance.

Cast iron nuts have good machinability and high strength. 932 bearing bronze and 673 bronze nuts are wear resistant. They have good machinability and fair corrosion resistance. PET plastic nuts are lightweight and corrosion resistant.

Travel distance per turn, also known as screw lead, is the distance a nut moves with one revolution of the lead screw.

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

Lead Screws—Right-Hand Threaded

1018 Carbon Steel
Thread Size	Lg.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Accuracy for Travel Distance per Turn	Thread Fit	Hardness	Tensile Strength, psi		Each
1/2"-8	3 ft.	2	2:1	0.25"	±0.009" per ft.	Class 2C	Brinell 126	64,000	000000000	000000
1/2"-8	3 ft.	8	8:1	1"	±0.009" per ft.	Class 2C	Brinell 126	64,000	000000000	00000
1/2"-8	6 ft.	2	2:1	0.25"	±0.009" per ft.	Class 2C	Brinell 126	64,000	000000000	00000
1/2"-8	6 ft.	8	8:1	1"	±0.009" per ft.	Class 2C	Brinell 126	64,000	000000000	00000
Black-Oxide 4140 Alloy Steel
1/2"-8	3 ft.	2	2:1	0.25"	±0.009" per ft.	Class 2C	Brinell 271	125,000	000000000	00000
1/2"-8	6 ft.	2	2:1	0.25"	±0.009" per ft.	Class 2C	Brinell 271	125,000	000000000	000000
304 Stainless Steel
1/2"-8	3 ft.	2	2:1	0.25"	±0.009" per ft.	Class 2C	Not Rated	Not Rated	000000000	00000
1/2"-8	3 ft.	8	8:1	1"	±0.009" per ft.	Class 2C	Not Rated	Not Rated	000000000	00000
1/2"-8	6 ft.	2	2:1	0.25"	±0.009" per ft.	Class 2C	Brinell 150	72,000	000000000	000000
1/2"-8	6 ft.	8	8:1	1"	±0.009" per ft.	Class 2C	Brinell 150	72,000	000000000	000000

Round Nuts—Right-Hand Threaded

Cast Iron
Thread Size	Lg.	Dia.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Hardness	Dynamic Thrust Load Cap., lbs.	Temperature Range, °F		Each
1/2"-8	1"	1.469"	2	2:1	0.25"	Class 2C	Brinell 217	Not Rated	__	000000000	000000
932 Bearing Bronze
1/2"-8	1"	1.469"	2	2:1	0.25"	Class 2C	Brinell 65	1,300	__	0000000	00000
PET Plastic
1/2"-8	1"	1.469"	2	2:1	0.25"	Class 2C	Not Rated	650	15° to 175°	0000000	00000

Externally Threaded Nuts—Right-Hand Threaded

Combine externally threaded nuts with a flange to create a custom flange nut.

						External Thread
Thread Size	Lg.	Dia.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Size	Lg.	Thread Fit	Hardness	Dynamic Thrust Load Cap., lbs.	Temperature Range, °F		Each
673 Bronze
1/2"-8	3/4"	1.125"	2	2:1	0.25"	15/16"-16	1/2"	Class 2C	Brinell 70	Not Rated	__	000000000	000000
1/2"-8	3/4"	1.125"	8	8:1	1"	15/16"-16	1/2"	Class 2C	Brinell 70	Not Rated	__	000000000	00000
PET Plastic
1/2"-8	3/4"	1.125"	2	2:1	0.25"	15/16"-16	1/2"	Class 2C	Not Rated	650	15° to 175°	000000000	00000

Flanges

Thread onto an externally threaded acme nut to create a custom flange nut.

1215 Carbon Steel
Flange Thread Size	Flange Dia.	Flange Thick.	Bolt Circle Dia.	Flange Hardness		Each
15/16"-16	2 5/8"	17/32"	2 3/32"	Not Rated	000000000	000000
303 Stainless Steel
15/16"-16	2 5/8"	17/32"	2 3/32"	Brinell 140	0000000	00000

Fast-Travel Ultra-Precision Lead Screws and Nuts

Multiple thread channels (also known as thread starts) create faster linear travel than lead screws with a single thread start. Operating with less backlash (play) than Precision Acme Lead Screws and Nuts, these lead screws and nuts provide increased nut life and more reliable movement in automated systems. All components are corrosion resistant for use in harsh environments. To ensure compatibility, select components that have the same thread type, thread size, and number of thread starts.

Travel distance per turn, also known as screw lead, is the distance a nut moves with one revolution of the lead screw.

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

Lead Screws—Right-Hand Threaded

303 Stainless Steel
Thread Size	Lg.	No. of Thread Starts	Thread Type	Speed Ratio	Travel Distance per Turn	Accuracy for Travel Distance per Turn	Hardness	Tensile Strength, psi		Each
1/2"-8	3ft.	2	Rounded Acme	2:1	0.25"	±0.0006" per in.	Brinell 160	90,000	00000000	0000000
1/2"-8	3ft.	4	Rounded Acme	4:1	0.5"	±0.0006" per in.	Brinell 160	90,000	00000000	000000
1/2"-8	3ft.	8	Rounded Acme	8:1	1"	±0.0006" per in.	Brinell 160	90,000	00000000	000000
1/2"-8	6ft.	2	Rounded Acme	2:1	0.25"	±0.0006" per in.	Brinell 160	90,000	00000000	000000
1/2"-8	6ft.	4	Rounded Acme	4:1	0.5"	±0.0006" per in.	Brinell 160	90,000	0000000	000000
1/2"-8	6ft.	8	Rounded Acme	8:1	1"	±0.0006" per in.	Brinell 160	90,000	0000000	000000

Flange Nuts—Right-Hand Threaded

Flange nuts with wear-compensating internal O-ring or wear-compensating spring maintain a tight fit even when their threads begin to wear.

				Flange
	Thread Size	Lg.	Dia.	Dia.	Thick.	No. of Thread Starts	Thread Type	Speed Ratio	Travel Distance per Turn	Bolt Circle Dia.	Tensile Strength, psi	Dynamic Thrust Load Cap., lbs.		Each
Acetal Plastic
B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	2	Rounded Acme	2:1	0.25"	1 1/8"	9,700	150	00000000	000000
B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	4	Rounded Acme	4:1	0.5"	1 1/8"	9,700	150	0000000	00000
B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	8	Rounded Acme	8:1	1"	1 1/8"	9,700	150	0000000	00000
Acetal Plastic with Wear-Compensating Spring
C	1/2"-8	2"	0.891"	1 39/64"	17/64"	2	Rounded Acme	2:1	0.25"	1 1/4"	9,700	25	00000000	00000
C	1/2"-8	2"	0.891"	1 39/64"	17/64"	4	Rounded Acme	4:1	0.5"	1 1/4"	9,700	25	0000000	00000
C	1/2"-8	2"	0.891"	1 39/64"	17/64"	8	Rounded Acme	8:1	1"	1 1/4"	9,700	25	0000000	00000

Ultra-Precision Lead Screws and Nuts

Operating with less backlash (play) than Precision Acme Lead Screws and Nuts, these provide increased nut life and more reliable movement in automated systems. Also known as single-start and self-locking lead screws and nuts, they have a single thread that runs the length of the screw. The nut travels only when the screw turns, so your system won’t unexpectedly move when the lead screw is at rest. All components are corrosion resistant for use in harsh environments. To ensure compatibility, select components that have the same thread type and thread size.

Travel distance per turn, also known as screw lead, is the distance a nut moves with one revolution of the lead screw.

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

Lead Screws—Right-Hand Threaded

303 Stainless Steel
Thread Size	Lg.	No. of Thread Starts	Thread Type	Speed Ratio	Travel Distance per Turn	Accuracy for Travel Distance per Turn	Hardness	Tensile Strength, psi		Each
1/2"-8	3 ft.	1	Rounded Acme	1:1	0.125"	±0.0006" per in.	Brinell 160	90,000	00000000	0000000
1/2"-8	6 ft.	1	Rounded Acme	1:1	0.125"	±0.0006" per in.	Brinell 160	90,000	00000000	000000

Flange Nuts—Right-Hand Threaded

Flange nuts with wear-compensating internal O-ring or wear-compensating spring maintain a tight fit even when their threads begin to wear.

				Flange
	Thread Size	Lg.	Dia.	Dia.	Thick.	No. of Thread Starts	Thread Type	Speed Ratio	Travel Distance per Turn	Bolt Circle Dia.	Tensile Strength, psi	Dynamic Thrust Load Cap., lbs.		Each
Acetal Plastic
B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	1	Rounded Acme	1:1	0.125"	1 1/8"	9,700	150	00000000	000000
Acetal Plastic with Wear-Compensating Spring
C	1/2"-8	2"	0.891"	1 39/64"	17/64"	1	Rounded Acme	1:1	0.125"	1 1/4"	9,700	25	00000000	00000