How to use an edge finder to locate the centre of a round part?

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Step 1 – Clean edges of part

Clean the edges of the part you will be finding the centre of.

This will help to ensure that the edge finder works accurately.

Step 2 – Secure part

Secure the part in a vice or base-plate mounted chuck.

Step 3 – Mount edge finder

Mount the edge finder in a collet or drill chuck and secure the tool to the spindle of your machine.

The centre of the edge finder’s shank will represent the centre of the spindle.

Step 4 – Centre part

Roughly centre your part and lower the edge finder using the quill feed lever.

Step 5 – Turn on machine

Turn on the machine so that it is running at around 500 RPM.

Step 6 – Move table

Move the table of the machine in the y direction so that the bottom of the edge finder moves towards the inside of the front of the part.

Initially, the edge finder will become centred.

Step 7 – Edge finder will become offset

When it makes contact with the part, however, it will become offset.

Step 8 – Move table

Then move the table so that the edge finder travels towards the backside of the part.

The edge finder will start to centre itself again.

Step 9 – Record value on y axis

Once the edge finder becomes offset once more, make a note of the value on the y axis shown on the digital read out.

Step 10 – Half this value

Half this value to find the centre of the part on the y axis.

e.g. 3.7010 ÷ 2 = 1.8505

Step 11 – Move table

Move the y axis until the edge finder reaches the centre you have calculated (in this case 1.8505).

Rezero the y axis.

After you have found the centrepoints on each axis, you will have found the centre of the part.