Lathe Workholding - 2026 Special Selection

What are thread gauges used for?

Thread gauges are used to identify and verify screw thread forms and sizes. They allow machinists, engineers and maintenance teams to quickly check thread pitch, angle and standard on bolts, screws and tapped holes without complex measuring equipment.

Which thread gauges should I use for internal and external threads?

For internal threads (such as nuts or tapped holes), use thread plug gauges. These are typically double-ended with Go and No-Go ends to confirm the thread is within tolerance. Plug gauges are most commonly manufactured to a 6H tolerance class for metric threads.

For external threads (such as bolts, screws or studs), use thread ring gauges. Like plug gauges, they are supplied as Go and No-Go gauges to ensure the thread meets specification. Ring gauges are typically produced to a 6g tolerance class for metric threads.

For tapered threads (such as NPT or BSPT), use tapered or stepped thread gauges, which verify the thread at a specific gauging position along the taper.

Are thread gauges suitable for both metric and imperial threads?

Thread gauges are manufactured specifically for the exact thread standard they are designed to check. Metric and imperial threads differ in pitch, thread form and dimensions, meaning they are not interchangeable.

Go/No-Go thread gauges are always produced to a specific standard and size. A metric gauge cannot be used to check an imperial thread, and vice versa. It is essential to select a gauge that matches the exact thread form, pitch and tolerance required.

Cutwel supply thread gauges covering major thread forms including Metric, BSP(G), Whitworth, NPT, UN and more, available in both coarse and fine pitches.

What materials are thread gauges made from?

Thread gauges are typically manufactured from hardened steel or stainless steel, offering high wear resistance and dimensional stability for consistent accuracy.

High-quality gauges are precision heat-treated and ground to maintain tight tolerances and long service life, especially in production environments.

Cutwel supply German-made thread gauges from Johs. Boss (JBO), manufactured for exceptional accuracy and reliability.

How can I improve my thread gauges tool life and prevent damage?

Improve tool life by handling and storing gauges correctly and avoiding excessive force. Gauges should be applied gently and never forced into position.

Keep gauges clean and free from debris and store them in protective cases to prevent accidental damage. Regular inspection ensures worn or damaged gauges are identified before accuracy is affected.

Do thread gauges need to be calibrated?

Yes, thread gauges should be calibrated to maintain accurate and reliable measurement.

Over time, wear may affect accuracy, particularly in production environments. Go/No-Go gauges should be calibrated at defined intervals against certified reference standards.

Cutwel offer both UKAS-accredited and manufacturer’s calibration services across the full range of precision thread gauges. Contact our Sales Team on 01924 869 610 or sales@cutwel.net.

Does Cutwel offer UKAS calibration on thread gauges?

Yes.* Cutwel offer both UKAS-accredited calibration and manufacturer’s calibration services.

UKAS-accredited calibration provides full traceability to national standards and is typically required for regulated industries and audited systems such as ISO 9001, aerospace and medical applications.

Manufacturer’s calibration offers a cost-effective solution for general engineering and workshop use where formal UKAS accreditation is not required.

If unsure which option is suitable, our team can advise.
*Only for new purchases

Does Cutwel offer custom or special thread gauges?

Yes. Cutwel partner with Johs. Boss (JBO) to supply custom and special thread gauges manufactured to your specification.

Non-standard sizes, special tolerances and modified thread forms can be produced to suit specific applications.

Visit our custom tools page or contact our expert team.

Does Cutwel offer express delivery for non-stocked or non-standard gauges?

Yes. Over 95% of standard thread gauges are stocked for next day UK delivery.

For non-stocked or non-standard gauges, an express 2–3 working day delivery service is available.

Contact our Sales Team on 01924 869 610 or email sales@cutwel.net.

Why buy thread gauges from Cutwel?

Cutwel supplies high-quality thread gauges designed for accuracy, durability and reliable performance in workshop and production environments.

A wide range of thread gauges makes it easy to find the correct solution.

Expert technical support, fast delivery and trusted brands such as Insize and JBO ensure confidence and after-sales support.

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