3/8"-8 Lead Screw Nuts | McMaster-Carr

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Number of Thread Starts

Travel Distance per Turn

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Thread Fit

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Tensile Strength

60,000 psi or greater

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30 Products

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.

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



	3/8"-8	3/4"	1.344"	Stub Acme	2:1	2	0.25"	Acme Class 2C	Brinell 217	Not Rated	Not Rated	—	95365A504	000000


	3/8"-8	3/4"	1.344"	Stub Acme	4:1	4	0.5"	Acme Class 2C	Brinell 217	Not Rated	Not Rated	—	95365A501	00000


	932 Bearing Bronze



			3/8"-8	3/4"	1.344"	Acme	2:1	2	0.25"	Acme Class 2C	Brinell 65	Not Rated	700	—	1343K114	00000


			3/8"-8	3/4"	1.344"	Acme	4:1	4	0.5"	Acme Class 2C	Brinell 65	Not Rated	700	—	1343K111	00000


			PET



					3/8"-8	3/4"	1.344"	Acme	2:1	2	0.25"	Acme Class 2C	Not Rated	Not Rated	350	15 to 175	1349K107	00000


					3/8"-8	3/4"	1.344"	Acme	4:1	4	0.5"	Acme Class 2C	Not Rated	Not Rated	350	15 to 175	1349K101	00000

Round Nuts—Left-Hand Thread

932 Bearing Bronze—932 bearing bronze and 673 bronze nuts are wear resistant. They have good machinability and fair 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.	Dia.	Thread Type	Speed Ratio	No. of Thread Starts	Travel Distance per Turn	Thread Fit	Hardness	Tensile Strength	Dynamic Thrust Load Cap., lb.		Each
932 Bearing Bronze



	3/8"-8	3/4"	1.344"	Acme	2:1	2	0.25"	Acme Class 2C	Brinell 65	Not Rated	700	1343K214	000000


	3/8"-8	3/4"	1.344"	Acme	4:1	4	0.5"	Acme Class 2C	Brinell 65	Not Rated	700	1343K211	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



		3/8"-8	5/8"	0.688"	Stub Acme	2:1	2	0.25"	9/16"-18	3/8"	Acme Class 2C	Brinell 70	Not Rated	Not Rated	—	95072A126	000000


		3/8"-8	5/8"	0.688"	Stub Acme	4:1	4	0.5"	9/16"-18	3/8"	Acme Class 2C	Brinell 70	Not Rated	Not Rated	—	95072A125	00000


		PET



				3/8"-8	5/8"	0.688"	Acme	2:1	2	0.25"	9/16"-18	3/8"	Acme Class 2C	Not Rated	Not Rated	350	15 to 175	95075A226	00000


				3/8"-8	5/8"	0.688"	Acme	4:1	4	0.5"	9/16"-18	3/8"	Acme Class 2C	Not Rated	Not Rated	350	15 to 175	95075A225	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



	9/16"-18	1 39/64"	13/32"	1 1/8"	Not Rated	95082A641	000000


	303 Stainless Steel



			9/16"-18	1 39/64"	13/32"	1 1/8"	Brinell 140	1329K11	00000

Precision Acme Lead Screws and Nuts

Pair with a motor in automated motion and positioning applications. A tight thread fit allows these lead screws and nuts to make accurate, repeatable starts and stops. 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. To ensure compatibility, please select components that have the same thread direction, thread size, and number of thread starts.

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



	3/8"-8	3/4"	1.344"	Stub Acme	1:1	1	0.125"	Acme Class 2C	Brinell 217	Not Rated	Not Rated	—	95365A521	000000


	932 Bearing Bronze



			3/8"-8	3/4"	1.344"	Acme	1:1	1	0.125"	Acme Class 2C	Brinell 65	Not Rated	700	—	1343K131	00000


			PET



					3/8"-8	3/4"	1.344"	Acme	1:1	1	0.125"	Acme Class 2C	Not Rated	Not Rated	350	15 to 175	1349K134	00000

Round Nuts—Left-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



	3/8"-8	3/4"	1.344"	Stub Acme	1:1	1	0.125"	Acme Class 2C	Brinell 217	Not Rated	Not Rated	—	95365A621	000000


	932 Bearing Bronze



			3/8"-8	3/4"	1.344"	Acme	1:1	1	0.125"	Acme Class 2C	Brinell 65	Not Rated	700	—	1343K231	00000


			PET



					3/8"-8	3/4"	1.344"	Acme	1:1	1	0.125"	Acme Class 2C	Not Rated	Not Rated	350	15 to 175	1349K135	00000

Externally Threaded Nuts—Right-Hand Thread

Image of Product. Front orientation. Contains Annotated. Precision Lead Screws and Nuts. 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



		3/8"-8	5/8"	0.688"	Stub Acme	1:1	1	0.125"	9/16"-18	3/8"	Acme Class 2C	Brinell 70	Not Rated	Not Rated	—	95072A124	000000


		PET



				3/8"-8	5/8"	0.688"	Acme	1:1	1	0.125"	9/16"-18	3/8"	Acme Class 2C	Not Rated	Not Rated	350	15 to 175	95075A224	00000

Flanges

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

Black-Oxide 1117 Carbon Steel—Black-oxide carbon steel flanges have mild corrosion resistance in dry environments and a dark surface color.

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
Black-Oxide 1117 Carbon Steel



	9/16"-18	1 39/64"	13/32"	1 1/8"	Brinell 135	1329K101	000000


	1215 Carbon Steel



			9/16"-18	1 39/64"	13/32"	1 1/8"	Not Rated	95082A641	00000


			303 Stainless Steel



					9/16"-18	1 39/64"	13/32"	1 1/8"	Brinell 140	1329K11	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.

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	3/8"-8	1"	0.625"	1 7/64"	3/16"	Rounded Acme	4:1	7/8"	4	0.5"	Not Rated	9,700	75	3	6350K35	000000


		Acetal with Wear-Compensating Spring



				C	3/8"-8	1 29/32"	0.703"	1 1/2"	3/16"	Rounded Acme	4:1	1 1/8"	4	0.5"	Not Rated	9,700	10	3	6350K55	00000

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.

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



	3/8"-8	Stub Acme	23/64"	11/16"	1	1:1	0.125"	Acme Class 2G	Rockwell B75	Not Rated	94815A011	00000


	Zinc-Plated Carbon Steel



			3/8"-8	Acme	23/64"	11/16"	1	1:1	0.125"	Acme Class 2G	Rockwell B75	Not Rated	98948A112	00000


			18-8 Stainless Steel



					3/8"-8	Stub Acme	23/64"	11/16"	1	1:1	0.125"	Acme Class 2G	Rockwell B97	Not Rated	95066A206	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



	3/8"-8	Stub Acme	23/64"	11/16"	1	1:1	0.125"	Acme Class 2G	SAE Grade 2	Rockwell B85	64,000	91808A014	00000


	18-8 Stainless Steel



			3/8"-8	Stub Acme	23/64"	11/16"	1	1:1	0.125"	Acme Class 2G	—	Rockwell B97	Not Rated	95066A355	00000