Worm Screws | McMaster-Carr

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Gear

Shaft-Mounted Worm

Worm

System of Measurement

Shaft Diameter

Gear Pitch Diameter

Gear Module

Speed Ratio

Number of Thread Starts

Material

Pressure Angle

Thread Direction

Bore Type

Gear Pitch

Number of Teeth

Worm Length

Face Width

Hub Diameter

Hub Material

Tooth Heat Treatment

Overall Width

Shaft Length

DFARS Specialty Metals

Exempt

Export Control Classification Number (ECCN)

REACH

RoHS

Compliant with Exemptions

Set Screw Included

Yes

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96 Products

Metal Worms and Worm Gears

Worm and

Gear Sold

Separately

Worm gears use screw threads to make large reductions to shaft speed while transmitting motion at a right angle. They transmit motion from worm to gear and cannot be reversed. For gears and worms to mesh correctly, they must have the same pressure angle, pitch/module, number of thread starts, and thread direction. These worms are compatible with plastic worm gears.

Worms


Keyed Bore	Round Bore

303 Stainless Steel—303 stainless steel worms won’t rust in wet environments, so they’re commonly used in food-processing plants and other areas with frequent cleaning.

Black-Oxide 1045 Carbon Steel—Black-Oxide 1045 carbon steel worms have rolled threads.

Hardened—Hardened 1045 carbon steel worms have ground threads, which are more durable and precise than rolled threads.

									Keyway		Hub
	Gear Module	Gear Pitch	Pressure Angle	Worm Lg.	Gear Pitch Dia.	OD	For Shaft Dia.	No. of Thread Starts	Wd.	Dp.	Dia., mm	Material	Thread Direction	Tooth Heat Treatment	Tooth Mechanical Finish	Set Screw Included		Each
Keyed Bore—1144 Carbon Steel



		—	12	14 1/2°	1 1/8"	1"	1.17"	1/2"	1	0.125"	0.063"	—	—	Right Hand	Not Hardened	Unfinished	—	000000000	000000


		—	10	14 1/2°	1 3/8"	1 1/4"	1.45"	5/8"	1	0.188"	0.094"	—	—	Right Hand	Not Hardened	Unfinished	—	000000000	00000
		—	8	14 1/2°	1 3/4"	1 1/2"	1.75"	3/4"	1	0.188"	0.094"	—	—	Right Hand	Not Hardened	Unfinished	—	000000000	000000
		—	6	14 1/2°	2 1/2"	2"	2.33"	7/8"	1	0.188"	0.094"	—	—	Right Hand	Not Hardened	Unfinished	—	000000000	000000


		Round Bore—Black-Oxide 1045 Carbon Steel



				0.5	—	20°	18 mm	11 mm	12 mm	5 mm	1	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000


				0.5	—	20°	18 mm	11 mm	12 mm	5 mm	2	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
				0.8	—	20°	30 mm	14 mm	15.6 mm	6 mm	1	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
				0.8	—	20°	30 mm	14 mm	15.6 mm	6 mm	2	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
				1	—	20°	32 mm	16 mm	18 mm	6 mm	1	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
				1	—	20°	32 mm	16 mm	18 mm	6 mm	2	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
				1	—	20°	32 mm	16 mm	18 mm	8 mm	1	—	—	—	—	Right Hand	Hardened	Ground	Yes	000000000	00000
				1.25	—	20°	37 mm	21 mm	23.5 mm	8 mm	1	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
				1.5	—	20°	40 mm	25 mm	28 mm	8 mm	1	—	—	20	1045 Carbon Steel	Right Hand	Not Hardened	Unfinished	No	000000000	00000
				1.5	—	20°	40 mm	25 mm	28 mm	8 mm	2	—	—	20	1045 Carbon Steel	Right Hand	Not Hardened	Unfinished	No	000000000	00000
				1.5	—	20°	40 mm	25 mm	28 mm	10 mm	1	—	—	20	1045 Carbon Steel	Right Hand	Hardened	Ground	No	000000000	00000


				2	—	14 1/2°	46 mm	31 mm	35 mm	12 mm	1	—	—	25	1045 Carbon Steel	Left Hand	Not Hardened	Unfinished	No	000000000	00000
				2	—	14 1/2°	46 mm	31 mm	35 mm	12 mm	1	—	—	25	1045 Carbon Steel	Right Hand	Not Hardened	Unfinished	No	000000000	00000
				2	—	14 1/2°	46 mm	31 mm	35 mm	12 mm	2	—	—	25	1045 Carbon Steel	Right Hand	Not Hardened	Unfinished	No	000000000	00000
				2.5	—	20°	63 mm	37 mm	42 mm	15 mm	2	—	—	30	1045 Carbon Steel	Right Hand	Not Hardened	Unfinished	No	000000000	00000


				Round Bore—303 Stainless Steel



						0.5	—	20°	18 mm	11 mm	12 mm	5 mm	1	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000


						0.5	—	20°	18 mm	11 mm	12 mm	5 mm	2	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
						0.8	—	20°	30 mm	14 mm	15.6 mm	6 mm	1	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
						1	—	20°	32 mm	16 mm	18 mm	6 mm	1	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
						1	—	20°	32 mm	16 mm	18 mm	6 mm	2	—	—	—	—	Right Hand	Not Hardened	Unfinished	Yes	000000000	00000
						1.5	—	20°	40 mm	25 mm	28 mm	8 mm	2	—	—	20	303 Stainless Steel	Right Hand	Not Hardened	Unfinished	No	000000000	00000

Shaft-Mounted Worms

4140 Alloy Steel—4140 alloy steel worms are already mounted on a shaft, so they’re ready to use with no machining required. The threads are ground into the shaft for higher precision than rolled threads, and hardened for additional durability and precision.

						Shaft, mm
	Gear Module	Pressure Angle	Worm Lg., mm	Gear Pitch Dia., mm	OD, mm	Dia.	Lg.	No. of Thread Starts	Thread Direction	Tooth Heat Treatment	Tooth Mechanical Finish		Each
4140 Alloy Steel



		0.5	20°	12	9	10	6	65	1	Right Hand	Hardened	Ground	000000000	000000


		0.5	20°	12	9	10	6	65	2	Right Hand	Hardened	Ground	000000000	00000
		0.8	20°	20	12	14	8	85	1	Right Hand	Hardened	Ground	000000000	00000
		0.8	20°	20	12	14	8	85	2	Right Hand	Hardened	Ground	000000000	00000
		1	20°	30	16	18	18	140	1	Right Hand	Hardened	Ground	000000000	000000
		1.5	20°	40	25	28	26	190	1	Right Hand	Hardened	Ground	000000000	000000

Gears

Bronze—Bronze gears have low friction and dissipate heat better than cast iron gears to provide a long service life for both the gear and the worm. They’re also more corrosion resistant than cast iron gears.

Cast Iron—Cast iron gears are strong and durable.

Speed Ratio—Speed ratio is the ratio by which output shaft speed is reduced. As speed decreases, torque increases.

												Hub
	Gear Module	Gear Pitch	Speed Ratio	No. of Teeth	Pressure Angle	Gear Pitch Dia.	For No. of Thread Starts	OD	Face Wd.	Overall Wd.	For Shaft Dia.	Dia.	Wd.	Material	For Thread Direction	Tooth Heat Treatment	Tooth Mechanical Finish		Each
Round Bore—Cast Iron



		—	12	18:1	18	14 1/2°	1 1/2"	1	1.69"	1/2"	1.125"	1/2"	1.25"	0.625"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	0000000


		—	12	20:1	20	14 1/2°	1.67"	1	1.85"	1/2"	1.125"	1/2"	1.25"	0.625"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	12	30:1	30	14 1/2°	2 1/2"	1	2.69"	1/2"	1.125"	1/2"	1.25"	0.625"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	12	40:1	40	14 1/2°	3.33"	1	3.52"	1/2"	1.25"	5/8"	1.5"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	12	60:1	60	14 1/2°	5"	1	5.19"	1/2"	1.25"	5/8"	1.75"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	10	20:1	20	14 1/2°	2"	1	2.22"	5/8"	1.375"	1/2"	1.25"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	10	30:1	30	14 1/2°	3"	1	3.22"	5/8"	1.375"	5/8"	1.75"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	10	40:1	40	14 1/2°	4"	1	4.22"	5/8"	1.375"	5/8"	1.75"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	10	50:1	50	14 1/2°	5"	1	5.22"	5/8"	1.375"	3/4"	2"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	10	100:1	100	14 1/2°	10"	1	10.22"	5/8"	1.375"	3/4"	2.5"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	8	20:1	20	14 1/2°	2 1/2"	1	2.78"	3/4"	1.5"	3/4"	1.75"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000


		—	8	30:1	30	14 1/2°	3 3/4"	1	4.03"	3/4"	1.5"	3/4"	1.75"	0.75"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	8	40:1	40	14 1/2°	5"	1	5.28"	3/4"	1.625"	1"	2.375"	0.875"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	6	20:1	20	14 1/2°	3.33"	1	3.71"	1"	1.875"	3/4"	1.875"	0.875"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	6	24:1	24	14 1/2°	4"	1	4.37"	1"	1.875"	3/4"	1.875"	0.875"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	6	30:1	30	14 1/2°	5"	1	5.37"	1"	1.875"	7/8"	2.25"	0.875"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	6	40:1	40	14 1/2°	6.67"	1	7.04"	1"	1.875"	1"	2.5"	0.875"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		—	6	72:1	72	14 1/2°	12"	1	12.37"	1"	2.25"	1 1/4"	3"	1.25"	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	000000
		1	—	60:1	60	20°	60 mm	1	63 mm	10 mm	20 mm	10 mm	30 mm	10 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000
		1	—	80:1	80	20°	80 mm	1	83 mm	10 mm	20 mm	10 mm	35 mm	10 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000
		1	—	100:1	100	20°	100 mm	1	103 mm	10 mm	20 mm	10 mm	40 mm	10 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000


		1	—	120:1	120	20°	120 mm	1	123 mm	10 mm	20 mm	10 mm	40 mm	10 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000
		1.5	—	30:1	30	20°	45 mm	1	49.5 mm	12 mm	22 mm	10 mm	30 mm	10 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000
		1.5	—	40:1	40	20°	60 mm	1	64.5 mm	12 mm	22 mm	12 mm	30 mm	10 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000
		2	—	10:1	20	14 1/2°	40 mm	2	46 mm	22 mm	35 mm	12 mm	33 mm	13 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000
		2	—	20:1	20	14 1/2°	40 mm	1	46 mm	22 mm	35 mm	12 mm	33 mm	13 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000
		2.5	—	10:1	20	20°	50 mm	2	57.5 mm	22 mm	36 mm	12 mm	35 mm	14 mm	Cast Iron	Right Hand	Not Hardened	Unfinished	000000000	00000


		Round Bore—Bronze



				—	12	20:1	20	14 1/2°	1.67"	1	1.87"	1/2"	1"	1/2"	1.25"	0.5"	Bronze	Right Hand	Not Hardened	Unfinished	000000000	000000


				—	12	30:1	30	14 1/2°	2 1/2"	1	2.7"	1/2"	1.12"	1/2"	1.19"	0.62"	Bronze	Right Hand	Not Hardened	Unfinished	000000000	000000
				—	12	40:1	40	14 1/2°	3.33"	1	3.54"	1/2"	1.12"	5/8"	1.44"	0.62"	Bronze	Right Hand	Not Hardened	Unfinished	000000000	000000
				—	10	20:1	20	14 1/2°	2"	1	2.24"	5/8"	1.245"	1/2"	1.25"	0.62"	Bronze	Right Hand	Not Hardened	Unfinished	000000000	000000
				—	10	30:1	30	14 1/2°	3"	1	3.24"	5/8"	1.245"	5/8"	1.69"	0.62"	Bronze	Right Hand	Not Hardened	Unfinished	000000000	000000
				—	10	40:1	40	14 1/2°	4"	1	4.24"	5/8"	1.245"	5/8"	1.69"	0.62"	Bronze	Right Hand	Not Hardened	Unfinished	000000000	000000
				—	10	50:1	50	14 1/2°	5"	1	5.24"	5/8"	1.375"	3/4"	1.94"	0.75"	Bronze	Right Hand	Not Hardened	Unfinished	000000000	000000
				0.5	—	10:1	20	20°	10 mm	2	11 mm	5 mm	12 mm	4 mm	9 mm	7 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.5	—	15:1	30	20°	15 mm	2	16 mm	5 mm	12 mm	4 mm	12 mm	7 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.5	—	20:1	20	20°	10 mm	1	11 mm	5 mm	12 mm	4 mm	9 mm	7 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.5	—	30:1	30	20°	15 mm	1	16 mm	5 mm	12 mm	4 mm	12 mm	7 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000


				0.5	—	40:1	40	20°	20 mm	1	21 mm	5 mm	12 mm	5 mm	15 mm	7 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.5	—	50:1	50	20°	25 mm	1	26 mm	5 mm	12 mm	5 mm	20 mm	7 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.5	—	60:1	60	20°	30 mm	1	31 mm	5 mm	12 mm	5 mm	25 mm	7 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.8	—	10:1	20	20°	16 mm	2	17.6 mm	9 mm	18 mm	5 mm	12 mm	9 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.8	—	20:1	20	20°	16 mm	1	17.6 mm	9 mm	18 mm	5 mm	12 mm	9 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.8	—	30:1	30	20°	24 mm	1	25.6 mm	9 mm	18 mm	5 mm	18 mm	9 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
				0.8	—	40:1	40	20°	32 mm	1	33.6 mm	9 mm	18 mm	6 mm	20 mm	9 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
1				—	10:1	20	20°	20 mm	2	23 mm	10 mm	20 mm	6 mm	16 mm	10 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
1	—			30:1	30	20°	30 mm	1	33 mm	10 mm	20 mm	6 mm	20 mm	10 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
1.25	—			20:1	20	20°	25 mm	1	28.75 mm	10 mm	20 mm	6 mm	20 mm	10 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000


1.5	—			10:1	20	20°	30 mm	2	34.5 mm	12 mm	22 mm	8 mm	22 mm	10 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
1.5	—			15:1	30	20°	45 mm	2	49.5 mm	12 mm	22 mm	10 mm	30 mm	10 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
1.5	—			20:1	20	20°	30 mm	1	34.5 mm	12 mm	22 mm	8 mm	22 mm	10 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000
1.5	—			30:1	30	20°	45 mm	1	49.5 mm	12 mm	22 mm	10 mm	30 mm	10 mm	Bronze	Right Hand	Not Hardened	Unfinished	000000000	00000

Plastic Worm Gears

These plastic gears are lighter and quieter than metal gears—pair them with metal worms for lubrication-free operation. Worm gears use screw threads to make large reductions to shaft speed while transmitting motion at a right angle. They transmit motion from worm to gear and cannot be reversed. For gears and worms to mesh correctly, they must have the same pressure angle, pitch/module, number of thread starts, and thread direction.

Gears

Acetal—Acetal gears are lightweight, and resist corrosion and chemicals. They absorb less moisture than nylon gears, so they’re less prone to dimensional changes. They’re best suited for light duty applications, such as prototyping.

Nylon—Nylon gears are lightweight and stronger than acetal gears.

Speed Ratio—Speed ratio is the ratio by which output shaft speed is reduced. As speed decreases, torque increases.

													Hub, mm
	Gear Module	Speed Ratio	No. of Teeth	Pressure Angle	Gear Pitch Dia., mm	For No. of Thread Starts	OD, mm	Face Wd., mm	Overall Wd., mm	For Shaft Dia., mm	Fabrication	Color	Dia.	Wd.	For Thread Direction		Each
Round Bore—Acetal



		0.5	10:1	20	20°	10	2	11	5	12	4	Molded	White	9	7	Right Hand	00000000	000000


		0.5	20:1	20	20°	10	1	11	5	12	4	Molded	White	9	7	Right Hand	00000000	00000
		0.5	30:1	30	20°	15	1	16	5	12	4	Molded	White	12	7	Right Hand	00000000	00000
		0.5	40:1	40	20°	20	1	21	5	12	5	Molded	White	15	7	Right Hand	00000000	00000
		0.5	50:1	50	20°	25	1	26	5	12	5	Molded	White	20	7	Right Hand	00000000	00000
		0.5	60:1	60	20°	30	1	31	5	12	5	Molded	White	25	7	Right Hand	00000000	00000
		0.8	10:1	20	20°	16	2	17.6	9	18	5	Molded	White	12	9	Right Hand	00000000	00000
		0.8	50:1	50	20°	40	1	41.6	9	18	8	Molded	White	25	9	Right Hand	00000000	00000
		0.8	60:1	60	20°	48	1	49.6	9	18	8	Molded	White	25	9	Right Hand	00000000	00000


		Round Bore—Nylon



				1	10:1	20	20°	20	2	23	10	20	6	Molded	Blue	16	10	Right Hand	00000000	00000


				1	30:1	30	20°	30	1	33	10	20	6	Molded	Blue	20	10	Right Hand	00000000	00000
				1	50:1	50	20°	50	1	53	10	20	8	Molded	Blue	30	10	Right Hand	00000000	00000
				1.5	10:1	20	20°	30	2	34.5	12	22	8	Molded	Blue	22	10	Right Hand	00000000	00000