1/2"-8 Threaded Rods | McMaster-Carr

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40,000 psi to 99,999 psi

100,000 psi or greater

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52 Products

About Lead Screws and Nuts

Compare lead screws and nuts by the size, direction, fit, and starts of their threads.

Acme 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, thread size, and number of thread starts.

Lead Screws—Right-Hand Thread

Carbon Steel—Carbon steel components are easier to machine than alloy steel components.

Alloy Steel—Alloy steel components are harder and stronger than carbon steel components.

18-8 Stainless Steel—18-8 stainless steel components have good corrosion resistance.

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

	Thread Type	Lg.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Fastener Strength Grade/Class	Hardness	Tensile Strength, psi	Specs. Met		Each
Carbon Steel



	1/2"-8	Acme	12"	1	1:1	0.125"	Acme Class 2G	SAE Grade 2	Rockwell B61	64,000	ASTM A108	98935A715	00000


	1/2"-8	Acme	3 ft.	1	1:1	0.125"	Acme Class 2G	SAE Grade 2	Rockwell B61	64,000	ASTM A108	98935A820	00000
	1/2"-8	Acme	6 ft.	1	1:1	0.125"	Acme Class 2G	SAE Grade 2	Rockwell B61	64,000	ASTM A108	98935A031	00000


	Alloy Steel



			1/2"-8	Acme	12"	1	1:1	0.125"	Acme Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	93410A920	00000


			1/2"-8	Acme	3 ft.	1	1:1	0.125"	Acme Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	93410A611	00000
			1/2"-8	Acme	6 ft.	1	1:1	0.125"	Acme Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	93410A320	000000


			18-8 Stainless Steel



					1/2"-8	Acme	12"	1	1:1	0.125"	Acme Class 2G	—	Rockwell B96	Not Rated	—	95061A612	00000


					1/2"-8	Acme	3 ft.	1	1:1	0.125"	Acme Class 2G	—	Rockwell B96	Not Rated	—	95061A816	00000
					1/2"-8	Acme	6 ft.	1	1:1	0.125"	Acme Class 2G	—	Rockwell B96	Not Rated	—	95061A524	000000

Lead Screws—Left-Hand Thread

Carbon Steel—Carbon steel components are easier to machine than alloy steel components.

Alloy Steel—Alloy steel components are harder and stronger than carbon steel components.

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

	Thread Type	Lg., ft.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Fastener Strength Grade/Class	Hardness	Tensile Strength, psi	Specs. Met		Each
Carbon Steel



	1/2"-8	Acme	3	1	1:1	0.125"	Acme Class 2G	SAE Grade 2	Rockwell B61	64,000	ASTM A108	98935A417	000000


	1/2"-8	Acme	6	1	1:1	0.125"	Acme Class 2G	SAE Grade 2	Rockwell B61	64,000	ASTM A108	98935A418	00000


	Alloy Steel



			1/2"-8	Acme	3	1	1:1	0.125"	Acme Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	93410A419	00000


			1/2"-8	Acme	6	1	1:1	0.125"	Acme Class 2G	ASTM Grade B7	Rockwell C35	125,000	ASTM A193	93410A420	000000

Hex Nuts—Right-Hand Thread

Hex nuts fasten and position lead screw components.

Carbon Steel—Carbon steel components are easier to machine than alloy steel components.

Zinc-Plated Carbon Steel—Zinc-plated carbon steel components have mild corrosion resistance and are easier to machine than alloy steel components.

18-8 Stainless Steel—18-8 stainless steel components have good corrosion resistance.

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

	Thread Type	Ht.	Wd.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Hardness	Tensile Strength		Each
Carbon Steel



	1/2"-8	Acme	31/64"	7/8"	1	1:1	0.125"	Acme Class 2G	Rockwell B75	Not Rated	94815A024	00000


	Zinc-Plated Carbon Steel



			1/2"-8	Acme	31/64"	7/8"	1	1:1	0.125"	Acme Class 2G	Rockwell B75	Not Rated	98948A115	00000


			18-8 Stainless Steel



					1/2"-8	Acme	31/64"	7/8"	1	1:1	0.125"	Acme Class 2G	Rockwell B97	Not Rated	95066A209	00000

Hex Nuts—Left-Hand Thread

Hex nuts fasten and position lead screw components.

Carbon Steel—Carbon steel components are easier to machine than alloy steel components.

18-8 Stainless Steel—18-8 stainless steel components have good corrosion resistance.

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

	Thread Type	Ht.	Wd.	No. of Thread Starts	Speed Ratio	Travel Distance per Turn	Thread Fit	Fastener Strength Grade/Class	Hardness	Tensile Strength, psi		Each
Carbon Steel



	1/2"-8	Acme	31/64"	7/8"	1	1:1	0.125"	Acme Class 2G	SAE Grade 2	Rockwell B85	64,000	91808A023	00000


	18-8 Stainless Steel



			1/2"-8	Acme	31/64"	7/8"	1	1:1	0.125"	Acme Class 2G	—	Rockwell B97	Not Rated	95066A366	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.

Lead Screws—Right-Hand Thread

1018 Low-Carbon Steel—Carbon steel lead screws and flanges have good machinability.

Black-Oxide 4140 Alloy Steel—Black-oxide alloy steel lead screws are hard and strong. They have mild corrosion resistance.

304 Stainless Steel—304 stainless steel lead screws have good corrosion resistance.

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

	Lg., ft.	Thread Type	Speed Ratio	No. of Thread Starts	Travel Distance per Turn	Accuracy for Travel Distance per Turn	Thread Fit	Hardness	Tensile Strength, psi		Each
1018 Low-Carbon Steel



	1/2"-8	3	Acme	2:1	2	0.25"	±0.009"/1 ft.	Acme Class 2C	Brinell 126	64,000	99030A316	000000


	1/2"-8	3	Stub Acme	8:1	8	1"	±0.009"/1 ft.	Acme Class 2C	Brinell 126	64,000	99030A300	00000
	1/2"-8	6	Acme	2:1	2	0.25"	±0.009"/1 ft.	Acme Class 2C	Brinell 126	64,000	99030A716	00000
	1/2"-8	6	Stub Acme	8:1	8	1"	±0.009"/1 ft.	Acme Class 2C	Brinell 126	64,000	99030A400	00000


	Black-Oxide 4140 Alloy Steel



			1/2"-8	3	Acme	2:1	2	0.25"	±0.009"/1 ft.	Acme Class 2C	Brinell 271	125,000	98940A623	00000


			1/2"-8	6	Acme	2:1	2	0.25"	±0.009"/1 ft.	Acme Class 2C	Brinell 271	125,000	98940A105	000000


			304 Stainless Steel



					1/2"-8	3	Acme	2:1	2	0.25"	±0.009"/1 ft.	Acme Class 2C	Not Rated	Not Rated	98980A978	00000


					1/2"-8	3	Stub Acme	8:1	8	1"	±0.009"/1 ft.	Acme Class 2C	Not Rated	Not Rated	98980A979	00000
					1/2"-8	6	Acme	2:1	2	0.25"	±0.009"/1 ft.	Acme Class 2C	Brinell 150	72,000	98980A365	000000
					1/2"-8	6	Stub Acme	8:1	8	1"	±0.009"/1 ft.	Acme Class 2C	Brinell 150	72,000	98980A183	000000

Round Nuts—Right-Hand Thread

Iron—Iron nuts have good machinability and high strength.

932 Bearing Bronze—932 bearing bronze and 673 bronze nuts are wear resistant. They have good machinability and fair corrosion resistance.

PET—PET plastic nuts are lightweight and corrosion resistant.

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

	Lg.	Dia.	Thread Type	Speed Ratio	No. of Thread Starts	Travel Distance per Turn	Thread Fit	Hardness	Tensile Strength	Dynamic Thrust Load Cap., lb.	Temp., ° F		Each
Iron



	1/2"-8	1"	1.469"	Acme	2:1	2	0.25"	Acme Class 2C	Brinell 217	Not Rated	Not Rated	—	95365A505	000000


	932 Bearing Bronze



			1/2"-8	1"	1.469"	Acme	2:1	2	0.25"	Acme Class 2C	Brinell 65	Not Rated	1,300	—	1343K15	00000


			PET



					1/2"-8	1"	1.469"	Acme	2:1	2	0.25"	Acme Class 2C	Not Rated	Not Rated	650	15 to 175	1349K15	00000

Externally Threaded Nuts—Right-Hand Thread

Image of Product. Front orientation. Contains Annotated. Precision Lead Screws and Nuts. Fast-Travel Precision Acme Lead Screws and Nuts, Externally Threaded Nuts—Right-Hand Thread.

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

673 Bronze—932 bearing bronze and 673 bronze nuts are wear resistant. They have good machinability and fair corrosion resistance.

PET—PET plastic nuts are lightweight and corrosion resistant.

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

								External Thread
	Thread Size	Lg.	Dia.	Thread Type	Speed Ratio	No. of Thread Starts	Travel Distance per Turn	Size	Lg.	Thread Fit	Hardness	Tensile Strength	Dynamic Thrust Load Cap., lb.	Temp., ° F		Each
673 Bronze



		1/2"-8	3/4"	1.125"	Acme	2:1	2	0.25"	15/16"-16	1/2"	Acme Class 2C	Brinell 70	Not Rated	Not Rated	—	95072A130	000000


		1/2"-8	3/4"	1.125"	Stub Acme	8:1	8	1"	15/16"-16	1/2"	Acme Class 2C	Brinell 70	Not Rated	Not Rated	—	95072A420	00000


		PET



				1/2"-8	3/4"	1.125"	Acme	2:1	2	0.25"	15/16"-16	1/2"	Acme Class 2C	Not Rated	Not Rated	650	15 to 175	95075A105	00000

Flanges

Image of Attribute. Front orientation. Contains Annotated.

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

1215 Carbon Steel—Carbon steel flanges have good machinability. However, they will rust when exposed to moisture.

303 Stainless Steel—303 stainless steel flanges have good corrosion resistance.

	Flange Dia.	Flange Thk.	Bolt Circle Dia.	Flange Hardness		Each
1215 Carbon Steel



	15/16"-16	2 5/8"	17/32"	2 3/32"	Not Rated	95082A642	000000


	303 Stainless Steel



			15/16"-16	2 5/8"	17/32"	2 3/32"	Brinell 140	1329K12	00000

Fast-Travel Ultra-Precision Lead Screws and Nuts


	Style B	Style C

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.

Lead Screws—Right-Hand Thread

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

	Lg., ft.	Thread Type	Speed Ratio	No. of Thread Starts	Travel Distance per Turn	Accuracy for Travel Distance per Turn	Hardness	Tensile Strength, psi		Each
303 Stainless Steel



	1/2"-8	3	Rounded Acme	2:1	2	0.25"	±0.0006"/1"	Brinell 160	90,000	6350K715	0000000


	1/2"-8	3	Rounded Acme	4:1	4	0.5"	±0.0006"/1"	Brinell 160	90,000	6350K716	000000
	1/2"-8	3	Rounded Acme	8:1	8	1"	±0.0006"/1"	Brinell 160	90,000	6350K717	000000
	1/2"-8	6	Rounded Acme	2:1	2	0.25"	±0.0006"/1"	Brinell 160	90,000	6350K115	000000
	1/2"-8	6	Rounded Acme	4:1	4	0.5"	±0.0006"/1"	Brinell 160	90,000	6350K23	000000
	1/2"-8	6	Rounded Acme	8:1	8	1"	±0.0006"/1"	Brinell 160	90,000	6350K24	000000

Flange Nuts—Right-Hand Thread


Style B	Style C


Style B	Style C

Acetal—Acetal nuts have good wear and corrosion resistance.

Wear-Compensating Spring—Flange nuts with wear-compensating internal O-ring or wear-compensating spring maintain a tight fit even when their threads begin to wear. They resist backlash to maintain accuracy over time, which is important in positioning applications such as 3D printing and robotics.

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

					Flange
	Style	Thread Size	Lg.	Dia.	Dia.	Thk.	Thread Type	Speed Ratio	Bolt Circle Dia.	No. of Thread Starts	Travel Distance per Turn	Hardness	Tensile Strength, psi	Dynamic Thrust Load Cap., lb.	No. of Mounting Holes		Each
Acetal



		B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	Rounded Acme	2:1	1 1/8"	2	0.25"	Not Rated	9,700	150	3	6350K153	000000


		B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	Rounded Acme	4:1	1 1/8"	4	0.5"	Not Rated	9,700	150	3	6350K43	00000
		B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	Rounded Acme	8:1	1 1/8"	8	1"	Not Rated	9,700	150	3	6350K44	00000


		Acetal with Wear-Compensating Spring



				C	1/2"-8	2"	0.891"	1 39/64"	17/64"	Rounded Acme	2:1	1 1/4"	2	0.25"	Not Rated	9,700	25	3	6350K191	00000


				C	1/2"-8	2"	0.891"	1 39/64"	17/64"	Rounded Acme	4:1	1 1/4"	4	0.5"	Not Rated	9,700	25	3	6350K63	00000
				C	1/2"-8	2"	0.891"	1 39/64"	17/64"	Rounded Acme	8:1	1 1/4"	8	1"	Not Rated	9,700	25	3	6350K64	00000

Ultra-Precision Lead Screws and Nuts


Style B	Style C

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, thread size, and number of thread starts.

Lead Screws—Right-Hand Thread

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

	Lg., ft.	Thread Type	Speed Ratio	No. of Thread Starts	Travel Distance per Turn	Accuracy for Travel Distance per Turn	Hardness	Tensile Strength, psi		Each
303 Stainless Steel



	1/2"-8	3	Rounded Acme	1:1	1	0.125"	±0.0006"/1"	Brinell 160	90,000	6350K713	0000000


	1/2"-8	6	Rounded Acme	1:1	1	0.125"	±0.0006"/1"	Brinell 160	90,000	6350K125	000000

Flange Nuts—Right-Hand Thread


Style B	Style C


Style B	Style C

Acetal—Acetal nuts have good wear and corrosion resistance.

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

					Flange
	Style	Thread Size	Lg.	Dia.	Dia.	Thk.	Thread Type	Speed Ratio	Bolt Circle Dia.	No. of Thread Starts	Travel Distance per Turn	Hardness	Tensile Strength, psi	Dynamic Thrust Load Cap., lb.	No. of Mounting Holes		Each
Acetal



		B	1/2"-8	1 1/2"	0.75"	1 1/2"	3/16"	Rounded Acme	1:1	1 1/8"	1	0.125"	Not Rated	9,700	150	3	6350K163	000000


		Acetal with Wear-Compensating Spring



				C	1/2"-8	2"	0.891"	1 39/64"	17/64"	Rounded Acme	1:1	1 1/4"	1	0.125"	Not Rated	9,700	25	3	6350K201	00000