Accommodating Bore Configurations for Your Shaft Collar or Coupling

Stafford Manufacturing Corp. designs and manufactures rigid couplings, shaft collars, and specialty mechanical parts used in automation, power transmission, motion control, and other OEM and MRO applications. We have collars and couplings available in square, threaded, hexagonal, keyed, and round bore configurations. In addition, we can add drive slots, press-fits, pulleys, or other special parts to meet your needs.

Here you’ll learn about each of these bore options and how to decide on the ideal shaft collar or coupling for your application. 


Types of Collar and Coupling Bore Configurations

Shaft collars and rigid couplings are machine components that slide over a shaft and lock into place with either set-screws or with clamping screws. They have three primary functions:

  • Holding components in place
  • Creating a connection between a shaft and another component
  • Positioning or locating parts along a shaft

Manufacturers supply variations of collars and couplings in different sizes, designs, and materials to fit a wide range of applications. Some of the common  shaft collar bore configurations include:

  • Round 
  • Threaded
  • Square
  • Hex
  • Keyed


Round Bores

As one of the most popular bore configurations, round shaft collars and couplings are used in various power transmission, motion control, and mounting applications. Serving as locators, spacers, bearing faces, or stops, they are most often used on shafts, tubing, pipes, and split hubs.

Round bore configurations are found in the following products:

  • One-piece shaft collars
  • Two-piece shaft collars
  • Hinge shaft collars
  • Threaded shaft collars
  • Heavy-duty shaft collars

Browse Stafford Manufacturing’s full selection of round bore shaft collars in our catalog

Browse Stafford Manufacturing’s full selection of round bore rigid couplings in our catalog

Round Bore Threaded Coupling
Round Bore Shaft Collar


Threaded Bores

Threaded shaft collars have a threaded interior that matches with certain threaded shafts. These provide superior grip, suitable for uses that require precise preload and location settings. Threaded shaft collars act as a stop to position parts or prevent them from moving along the shaft. 

Threaded bore configurations are found in the following products:

  • One-piece or two-piece split clamp UNF/ UNC Threaded Bore Shaft Collars
  • One-piece or two-piece Accu-Clamp™ Threaded Shaft Collars
  • One-piece or two-piece ACME Threaded Collars
  • One-piece or two-piece UNF/UNC Threaded Split Hub Collars
  • Threaded Hinge collars

See the threaded shaft collars we provide

Threaded Shaft Collar
Threaded Hinge Shaft Collar


Square and Hex Bores

Stafford Manufacturing produces hexagonal and square shaft collars and couplings to fit onto hexagonal and square-shaped shafts. Square and hex shaft couplings and collars are easy to install and customize with mounting capabilities if necessary. They provide high clamping power and are primarily used in food processing and conveyor systems. 

Square bore configurations are available in:

  • Two-piece split clamp styles collars
  • Mounting two-piece stackable styles collars
  • Precision Sleeve Rigid Couplings

Hex bore configurations are available in:

  • One-piece split clamp styles
  • Two-piece split clamp styles.
  • Precision Sleeve Rigid Couplings

Look through our full selection of hex and square shaft collars and couplings here.

Hex Bore Precision Rigid Coupling
Hex Bore Shaft Collar
Square Bore Precision Rigid Coupling
Square Bore Shaft Collar



Shaft couplings can be configured with keyways, but they are not always required. They should be utilized for couplings designed to support radial alignment and loads with high torque. Determine whether radial alignment or additional torque will affect the system’s overall operation, and then use that analysis to decide whether you need a keyway.

Keyed Rigid Coupling
Keyed Shaft Collar


Selecting Your Shaft Collar or Coupling Configuration

The right shaft collar or coupling is the one that fits your configuration and application.  In some cases, a certain type of configuration may be better than other options (i.e.  square, hex, and keyed shafts can handle more torque). Keyed shafts in particular have a locking position that makes accommodating higher torques possible.

Standard bores are cost-effective options that fit most basic applications. Stafford Manufacturing carries round, threaded, square, hex, and keyed bores as standard products, so our customers can rely on us to have what they need, when they need it. In addition, Stafford is the only stocking manufacturer of a full line of square and hex bore products.

While standard bore products serve most applications at the lowest cost, some applications require customized collars or coupling bores. Stafford has been manufacturing custom shaft collars and couplings for over 47 years and we can produce to your exact needs at a fair price with no minimum order quantity.

Stafford Is Your Custom Shaft Collar and Coupling Manufacturer

Stafford Manufacturing has nearly 50 years of industry experience. As an ISO 9001:2015-certified business, our staff has the quality control standards in place to produce the highest quality shaft collars and rigid couplings. We have a large selection of products, which enables us to assist you in selecting the ideal bore configuration for your particular needs and price range. If you can’t find a shaft collar or coupling that meets your needs, we will collaborate closely with you to design and produce a custom solution.

Contact us or request a quote today to learn more about our standard and custom offerings. 


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