Custom Manufacturing Of Precision Ground Case-Hardened Linear Shafting and Guide Bars


Application Support personnel are available to assist you with your inquiries, help you with drawings, and provide you with any other information you might require to help make the best choice when it comes to your linear shafting applications.

Shafting Tolerance Guide

To see a chart of material sizes and tolerances in available in Imperial and Metric sizes, click here.

Did you Know?

Diameter tolerance is not necessarily the same as “roundness” (how well a given cross section of a shaft resembles a perfect circle) or “cylindricity” (how well the overall length of a shaft resembles a perfect cylinder).


Did you Know?

When compared to unhardened steel bars, hardened steel typically has:

• An increase in tensile strength of approximately 100% for diameters up to 3/4" and 40-60% above 3/4".  

• An increase of 3 times the tensile strength for the hardened skin of the bar.

• An 80% increase in overall torsional strength.  

• 10 times the wear resistance (depending on the application).

• A refined core structure which makes the resulting hardened bars very stable in use.

Please Contact Us directly for more information about other material and material options.


Material Specifications

In choosing the correct product and specifications for your linear applications, many of the following factors should be taken into account to ensure that the desired performance and suitable degree of precision is achieved.   Unless they are properly anticipated, significant loads and stresses may be generated within a given application which could have potentially damaging effects.

Material Available

Sourced from a number of world-class suppliers to ensure maximum quality and availability, Strongbar offers a wide range of case-hardened linear shafting and guide bars from generous stock. We typically stock, grind and machine a broad range of both imperial and metric high-carbon alloy steels and stainless steels in a range of tolerances.

• Carbon steels to B.S. 070M55 (solid and hollow/tube)
• Stainless steels AISI 440C (solid only)
• Hard chrome and plated shafts

Should you require custom materials that vary in, for example, chemical composition, we are pleased to offer the ability to source and to machine almost all types of material. 

Available diameters and tolerances

The diameter tolerance of a shaft represents the potential variance in the outer diameter dimension of a linear shaft or guide bar at any point along its length. Different class tolerances specify the degree of permissible variance within each class. In certain applications where uniform distribution of bearing loads, longer travel life and improved accuracy are critical, the correct selection of the outer diameter tolerance is crucial to ensure longer life and improved precision in the application. 

Strongbar can supply virtually any size and tolerance that you may require as a result of our ability to centreless grind to any diameter. 

• 3mm to 80mm Ψ

• 3/16" to 3" Ψ and specials up to 6" Ψ

• Metric tolerances h6 and h7

• Imperial tolerances Class L or S

• Chrome and plated shafting to h6, Class L and S tolerances

• Special tolerances available to order

View a Shafting Tolerance Guide: Click here

Aside from a complete range of general industry standard diameter tolerances, Strongbar is pleased to offer a private brand of linear shafting with a tolerance not otherwise available in the marketplace. Please contact us directly for more information about our private brand.

Hardness and Depth of Hardness

As one of the more critical elements in shafting selection, the appropriate choice of material hardness and the depth of hardness (for case hardened material) will ensure an appropriate resistance to wear, higher strength, and increased load-carrying capacity. The result is an improved resistance against deformation, bending, and rotational fatigue, as well as the ability to maintain critical dimensions over a longer period of time which will extend the life of your applications.

Strongbar is offers shafts ranging in hardness from:

• Rockwell 50-55C (Stainless Steels and 440C)

• Rockwell 60-65C (Solid and hollow/tube)

• Hard chrome and plated steels, typically plated to a standard plating depth pf .015 ±.005mm micro-crack structure




Duty (mm)

Duty (mm)



0 - 10mm Ψ




Equivalent Depths Apply to Imperial Sizes


11 - 16mm Ψ





17 - 25mm Ψ





26 - 63mm Ψ





Over 64mm Ψ




Strongbar also has the ability to control the hardening process in-house which allows for greater flexibility in machining and which results in a much higher degree of precision and quality for finished goods, especially for small diameter shafts where annealing and through-core hardening is a potential concern.

Surface Finish

Surface finish is a key variable affecting the smoothness of travel, the load level capacity, resistance due to friction, and the overall life of a shaft.  Strongbar is pleased to offer surface finishes better than industry standards whenever your circumstances require it. 

• Standard finishes: ground and polished to 8-12 CLA
• Special finish: 4 CLA available if required

Length Tolerance

Stock is generally supplied with a standard finished length tolerance of ±1/32” for shafts up to 1-1/4” diameter, and ±1/16” for shafts over 1-1/4” diameter. For metric, we offer a standard finished length tolerance of ±.01mm. Closer tolerances are available upon request.  

Standard Shaft and Extra-Long Shafts

Standard shaft lengths are stocked in 3m (188") lengths.  Extra-long shafts are available by special order to provide single imperial lengths up to 300” and single metric lengths up to 7.6m.  In addition, we are capable of providing multi-piece shafts up to virtually unlimited lengths through shaft coupling and end-machining whereby a series of shafts are joined end-to-end. Please call if you requires to inquire about these options.

Straightness Tolerance

Another key element to ensure precision in a given application is the overall straightness of a linear shaft. With a straighter shaft, cutting tools, gauges and positioning tables will be able to achieve a higher degree of accuracy and precision than may otherwise be achievable.  For manufacturers, starting with a straighter shaft will translate into less work-around and variance compensation in the later stages of both the design and construction process, thereby increasing overall turnaround time and improving the final quality of the end products.

Standard straightness tolerances are .001" to .002" per foot cumulative with much tighter tolerances available if required.  Strongbar is very pleased to offer the capability for straightness tolerance that is unparalleled in the industry.


Standard chamfers on cut-to-length shafting and machined parts are generally 1/16” x 45°. Depending on your requirements, any type of chamfering is available. Please specify your preference at the time of order.

Other Specifications

There are many other material considerations which may need to be taken into account during the material selection process other than those listed above. A few of the less common ones include:

• Sensitivity to electrical conductivity and/or magnetism
• Corrosion resistant finishes and plating
• Special materials and chemical composition


Should you have additional questions at any time, Application Support personnel are available to assist you with your inquiries. Please Contact Us directly for more information about other material and material options.


 • Return to: Last Page
 • Return to: Products
 • Return to: Home Page

© Strongbar (UK) Ltd. 2008