The different types of thread gauges that you must know about

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An international standard governs the production of components in manufacturing. For a product to be accepted by a standard, it must meet a specific set of dimensions and tolerances. These dimensions must be checked and recorded frequently.

A thread micrometer is used to measure the effective pitch diameter of a thread, which has a vee and a conical anvil. A standard flat-face micrometer and thread wire sets can also be used to accomplish this. Thread gauges are used to verify that the thread dimensions are within a specified range, not to actually measure the thread itself.

Hardened and ground to exacting dimensions, thread gauges comply with industry standards.

What are the different types of thread gauges?

Checking the dimensions of a thread’s form angle, pitch, and diameter can be done with the help of a thread gauge. When checking internal threads, plug gauges are used, and when inspecting external threads, ring gauges are used. A NO GO gauge and a GO gauge are the two parts of each gauge. The thread should be checked using both parts.

A GO ring gauge and a NO GO ring gauge are required when machining a part with an external thread. Screw the GO gauge onto the part. There should be no way to screw the NO GO gauge on.

A GO plug gauge should only be screwed into an internal thread, but a NO GO should not. This ensures that the thread is within its permissible dimensions.

A wide range of gauges is available for all thread forms and sizes, from 60-degree form (ANSI UNC/UNF/UNJ) to 55-degree form (BSP/BSF/BSW) to Trapezoidal and Acme form.

Threads with a Slope

A stepped plug/ring gauge is needed to check threads with tapered threads (NPT and BSPT).

Using these gauges, you can measure the effective diameter of the tapered thread at a predetermined distance from the component face. A seal is formed on the tapering end at a specific position when mating components are fitted together. Components are fitted with a thread gauge. Between the section of the upper and lower limits of the gauge, the thread or component face should begin (the flat section).

With pre-plated gauges

Before applying a coat to the thread, this type of gauge is used to measure its diameter. The information provided is critical because different components will require different coating thicknesses.

If the finished thread size is M16 x 2 and the coating is 0.1 mm thick, then the appropriate gauge must be selected. The new gauge’s major and minor diameters can then be accurately calculated.

The lead or pitch of the screw thread is measured using metric thread gauges. Thread pitch gauges are used to determine the pitch of a thread on a screw or in a tapped hole by comparing it to a standard. Instead of being a precision measuring tool, pitch gauges allow the user to quickly determine the profile of a given thread and classify the thread according to its shape and pitch.

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