What Is a Telescopic Gauge? Parts, Uses & How to Use It Easily

Published: 2 Jul 2025

Need a tool to measure inside tight spaces like holes or pipes? A telescopic gauge is the perfect tool. It’s easy to use and gives accurate results when used with a micrometer. In this post, you’ll discover everything about this handy measuring tool—its parts, how it works, and how to use it the right way.

What is a Telescopic Gauge?

A telescopic gauge is a T-shaped tool used to measure the inside diameter of holes, pipes, grooves, or cylinders. It doesn’t show the measurement itself, but is used with a micrometer to get the exact size. It’s an Adjustable and indirect measuring tool and also known as a telescopic bore gauge.

Telescopic Gauge Parts

Telescopic Gauge Diagram

A telescoping gauge consists of a few parts that work together to measure internal diameters. Each part plays a simple but important role:

Locking Knob or Screw

This is used to lock the measuring arms in place once they expand inside the hole.

Telescopic Arms (or Rods)

These are two spring-loaded rods that move outward to fit the size of the bore or hole. They are the parts that touch the inside surface.

Spring Mechanism

The spring pushes the arms out, so the gauge opens to fit the hole automatically.

Measuring Tips (Contact Faces):
These are the rounded ends of the arms that make contact with the bore wall.

How to Use Telescopic Gauge

Step-by-step guide:

Insert the gauge into the hole
Press the rods to fit inside
Wiggle gently to center it
Lock the screw to hold the rods
Remove the gauge
Measure the rod ends using a micrometer.

Telescopic Gauge Uses

List common applications in mechanical work:

Measuring internal bores and holes
Used in engine repair and maintenance
Helpful in lathe and milling operations
Verifying hole size in machining and fitting jobs

Conclusion

A telescopic gauge is a simple but powerful tool in mechanical work. It’s perfect for measuring the inside size of bores and holes when paired with a micrometer. With just a few easy steps, it helps you get accurate internal measurements. Whether you’re a student, technician, or machinist, learning how to use this tool can save time and improve your results.

FAQs

What is the telescopic gauge price?

The price varies between $10 and $50 based on quality and brand.

What comes in a telescopic gauge set?

A standard set includes multiple gauges covering different diameter ranges, typically 6 pieces.

What is the telescopic gauge range?

A telescopic gauge can measure inside sizes from 8 mm to 150 mm, or about 5/16 inch to 6 inches.

What is the least count of a telescopic gauge?

The gauge itself has no direct least count. Accuracy comes from the micrometer reading.

Is a telescoping bore gauge the same as a telescopic gauge?

Yes, both terms refer to the same tool used for internal measurements.