Step Down Axles | McMaster-Carr

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31 Products

About Shafts

Step-Down Rotary Shafts

A shoulder near the end of the shaft provides a stop for gears, sprockets, and bearings. The edges are chamfered to remove sharp corners, reducing damage to bearings, housings, and other components during installation. All are turned, ground, and polished to tight diameter and straightness tolerances.

1045 carbon steel shafts balance high strength and good machinability, making them ideal for general purpose use. They are stronger than aluminum and stainless steel shafts but not as corrosion resistant. 303 stainless steel shafts are more corrosion resistant than steel shafts but also more difficult to machine.

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

Step Down × Straight End

Step-Down End × Straight End

		Step
Lg.	Lg. Tolerance	Dia.	Lg.	Straightness Tolerance	Edge Type	Hardness Rating	Hardness		Each
Inch—1045 Carbon Steel
3/4" Dia. (Tolerance: -0.001" to 0")
6"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	000000	000000
9"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	000000	00000
12"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	000000	00000
1" Dia. (Tolerance: -0.001" to 0")
6"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	000000	00000
9"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	000000	00000
12"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	000000	00000
Inch—303 Stainless Steel
3/4" Dia. (Tolerance: -0.001" to 0")
6"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 160	0000000	00000
9"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 160	0000000	00000
12"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 160	0000000	00000
1" Dia. (Tolerance: -0.001" to 0")
6"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 160	0000000	00000
9"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 160	0000000	00000
12"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 160	0000000	00000

Step-Down on Both Ends

		Step
Lg.	Lg. Tolerance	Dia.	Lg.	Straightness Tolerance	Edge Type	Hardness Rating	Hardness		Each
Inch—1045 Carbon Steel
3/4" Dia. (Tolerance: -0.001" to 0")
12"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	000000
18"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000
24"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000
1" Dia. (Tolerance: -0.001" to 0")
12"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000
12"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000
18"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000
18"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000
24"	-0.005" to 0.005"	1/2"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000
24"	-0.005" to 0.005"	3/4"	3"	0.003" per ft.	Chamfered	Medium	Brinell 150	0000000	00000

Ball Splines and Bearings

Create a compact linear and rotary motion system for applications requiring complex, fast movements, such as robotics. The grooves on the ball splines transmit rotary power as ball bearings move smoothly and precisely along their length, even at high speeds.

Ball splines are alloy steel for high strength and wear resistance. They're hardened on the outside for additional wear resistance while the center is soft enough to absorb stress from shifting loads. Those with a step-down end have a shoulder near the end to stop gears, sprockets, and bearings.

Bearings have a retaining ring groove, so they can be positioned in your system with a retaining ring (not included). Bearings with a keyway include a machine key for attaching your load. Flanged bearings have a surface with mounting holes for attaching your load.

Ball Splines

Splined End × Step-Down End

Four Splines

				Spline			Step
Dia., mm	Dia. Tolerance, mm	Lg., mm	Lg. Tolerance, mm	Lg., mm	No. of	Root Dia., mm	Dia., mm	Dia. Tolerance, mm	Lg., mm	Surface Smoothness, microinch	Edge Type	Hardness Rating	Hardness	Heat Treatment		Each
Metric—52100 Alloy Steel
Splined End × Step-Down End
18.2	-0.021 to 0	350	-0.7874 to 0.7874	200	4	16.4	15	-0.018 to 0	150	16	Chamfered	Very Hard	Rockwell C60	Case Hardened	00000000	0000000
23	-0.021 to 0	350	-0.7874 to 0.7874	200	4	20.6	20	-0.021 to 0	150	16	Chamfered	Very Hard	Rockwell C60	Case Hardened	00000000	000000
28	-0.021 to 0	450	-0.7874 to 0.7874	300	4	24.8	25	-0.021 to 0	150	16	Chamfered	Very Hard	Rockwell C60	Case Hardened	00000000	000000
37.4	-0.025 to 0	550	-0.7874 to 0.7874	400	4	33.1	30	-0.021 to 0	150	16	Chamfered	Very Hard	Rockwell C60	Case Hardened	00000000	000000

Bearings

				Material						Keyway
For Spline Dia., mm	For No. of Splines	Overall Lg., mm	OD, mm	Bearing	Ball	Dynamic Load Cap., lbs.	Max. Dynamic Torque, in.-lbs.	With Retaining Ring Grooves	Includes	Dp., mm	Lg., mm	Wd., mm		Each
18.2	4	60	32	Steel	Steel	1,750	734	Yes	Machine Key	2.5	26	4	00000000	0000000
28	4	80	45	Steel	Steel	4,150	2,557	Yes	Machine Key	4	41	7	00000000	000000

Flanged Bearings

					Material					Mounting Hole
For Spline Dia., mm	For No. of Splines	Overall Lg., mm	Flange OD, mm	OD, mm	Bearing	Ball	Dynamic Load Cap., lbs.	Max. Dynamic Torque, in.-lbs.	With Retaining Ring Grooves	No. of	Thread Size		Each
18.2	4	60	51	32	Steel	Steel	1,750	734	Yes	4	M4 × 0.7 mm	00000000	0000000
23	4	70	60	37	Steel	Steel	2,750	1,433	Yes	4	M5 × 0.8 mm	00000000	000000
28	4	80	70	45	Steel	Steel	4,150	2,557	Yes	4	M6 × 1 mm	00000000	000000
37.4	4	100	90	60	Steel	Steel	6,900	5,637	Yes	4	M8 × 1.25 mm	00000000	000000