What Are the Connection Methods for a Linear Shaft and Other Components?

A linear shaft is normally connected to a machine frame through shaft supports, clamping blocks, threaded ends, shoulders or mounting holes. The correct method depends on whether the shaft must remain fixed, transmit axial force, allow removal or receive continuous support along its length.

Unlike a rotating transmission shaft, a precision linear shaft mainly provides a hardened and accurately finished running surface for linear bearings. Welding, keyways and flexible couplings are therefore not standard connection methods for most linear-bearing applications.

1. End Supports and Shaft Support Blocks

End supports are one of the most common ways to install a round linear shaft. The shaft is inserted into a support block at each end and secured by a clamping screw, split clamp or set screw.

Common support structures include:

• Flange-type shaft supports mounted on a vertical plate
• Base-mounted supports installed on a horizontal machine frame
• Split clamping blocks that can be opened for easier shaft installation

This method is simple, removable and suitable for automation equipment, testing devices, packaging machinery and other systems using linear bearings. Both supports must be positioned accurately to prevent the shaft from being forced out of alignment during tightening.

2. Clamping Connections

A clamping connection holds the shaft through radial compression rather than permanent machining. It may use a split support, clamping collar or a machined holder with tightening bolts.

Clamping is generally preferred over a set screw acting directly on the shaft surface because it distributes the holding force over a larger area. A pointed set screw may leave an indentation on the hardened surface, making later adjustment or bearing installation more difficult.

When axial movement must be prevented, the clamping force should be checked against the actual axial load and vibration level rather than relying only on the nominal shaft diameter.

3. Threaded and Tapped Shaft Ends

A shaft end can be externally threaded to accept a nut or internally tapped to receive a bolt. These methods are useful when the shaft must be fixed against a plate, bracket or end structure.

• External thread: secured with a nut and washer
• Internal thread: fixed with a bolt inserted from the mounting plate
• Thread plus shoulder: provides both axial location and mechanical fastening

Threads should normally be machined before final assembly. Thread dimensions, usable length, shoulder position and required concentricity should be shown clearly on the drawing.

4. Stepped Ends and Shaft Shoulders

A stepped shaft end provides a defined shoulder that locates the shaft axially against a bracket, plate or support. A nut, bolt, retaining ring or clamping component can then hold it in position.

This structure is useful when the installation requires repeatable axial positioning. However, reducing the shaft diameter creates a change in cross-section, so the shoulder radius and remaining diameter must be suitable for the load.

5. Cross Holes, Pins and Bolted Connections

A transverse hole can be added near the shaft end for a locating pin, retaining pin or bolt. Flat sections may also be machined where a set screw or clamping element needs a defined contact surface.

Because drilling removes material and creates a local stress concentration, the hole position should not be selected arbitrarily. Avoid placing cross holes in the bearing travel area or in a highly loaded section of the shaft.

6. Supported Linear Shaft Installation

For longer strokes or loads that could cause an unsupported round shaft to deflect, a supported linear shaft can be used.

In this design, the shaft is fixed continuously to an aluminum support base. The base is bolted directly to the machine structure through its mounting holes, and an open-type linear bearing travels along the exposed shaft surface.

Continuous support improves rigidity compared with a shaft supported only at its ends, but the machine mounting surface must still be sufficiently flat and straight. Tightening bolts against an uneven base can introduce installation error into the guide system.

Which Connection Method Should You Choose?

Before selecting the connection, confirm the shaft diameter, unsupported length, radial and axial loads, required alignment, installation space and whether the shaft needs to be removed during maintenance.

Details to Include on a Custom Shaft Drawing

If the shaft requires end machining, the drawing should clearly specify:

• Finished shaft diameter and total length
• Thread specification and effective thread length
• Step diameters, shoulder positions and corner radii
• Hole diameter, depth and distance from the shaft end
• Required dimensional tolerances
• Bearing travel area and surfaces that must remain undamaged

DLY supplies precision linear shafts made mainly from GCr15 bearing steel and C45 high-carbon steel. Available processing includes cutting, drilling, tapping, threading, chamfering and stepped-end machining according to confirmed drawings.

For standard shaft structures and additional product information, see the linear shaft rod product page.

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