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How to use a telescopic gauge?

Shop for Telescopic Gauges
Different sizes of telescopic gauge

Step 1 – Select gauge size

Select the correct size of telescopic gauge for the size of bore you wish to measure.

Step 2 – Lock telescopic rods

Using your finger and thumb on your dominant hand press the two telescopic rods into their casing. Whilst still holding the telescopic rods in position use your non-dominant hand to turn the locking screw in a clockwise direction to hold them in position.

Placing the telescopic gauge in a bore to measure its size

Step 3 – Place gauge in bore

Place the top of the telescopic gauge inside the bore at the exact position you wish to measure. Then slowly twist the locking screw anticlockwise until the telescopic rods come out of their casing. Continue twisting the locking screw until the ends of the telescopic rod touch the sides of the bore.

Rocking telescopic gauge to achieve self centring

Step 4 – Self centring

Next you will need to rock the gauge with the handle backwards and forwards slightly to make sure the gauge is perfectly aligned with the diameter you wish to measure.

Locking screw on a telescopic gauge

Step 5 – Lock telescopic rods

Twist the locking screw clockwise until the telescopic rods are held firmly in place, and remove the tool from the hole.

Wonkee Donkee says "Make sure the arms are locked tightly, otherwise they may loosen and give a false reading"
Measuring a telescopic gauge with a micrometer

Step 6 – Measure telescopic rods

Finally you will need to measure the ends of the telescopic rods with either a micrometre or a vernier calliper for an accurate measurement of the diameter.

Wonkee Donkee says "You will need to repeat steps one to six twice to ensure you have an accurate reading"