TEC Chuck Jaws

How To Bore Out Soft Jaws

Boring and Turning Soft Jaws

When you’re ready to bore or turn a diameter to clamp your work piece on your soft jaws, the following simple guidelines may be useful although you can usually find detailed instructions sent by the chuck manufacturer with the chuck package.

Step 1

Prepare a disc/bung for clamping the chuck up, making sure the wall thickness and material strength is strong enough to take the chuck pressure. You will need different sizes to cover different work piece and chuck diameters. Make sure the soft top jaws are correctly fitted in position on the base jaws.

Step 2

Actuate the chuck so the base jaws are open and set the diameter to be gripped around the middle of the maximum jaw stroke.

Step 3

Place the disc/bung on the chuck face making sure when you clamp up that the bung is totally flat against the face. Clamp the bung.

Step 4

Whilst gripping the bung, bore out the soft jaws to the desired diameter and finish required to grip the work piece. Ideally the gripping pressure should be set to the same pressure the work piece will be clamped at.

Step 5

After the jaws have been bored out do a test to make sure the work piece is clamped securely and the accuracy is correct before continuing to machine the work piece.

Turning soft jaws is very similar except you will need a ring instead of a bung to clamp the jaws for turning. The chuck jaws must have a diameter turned for the ring, usually at the back of the jaws. Once this is machined the ring can be clamped and the required diameter work piece turned.


If you don’t want to spend your valuable time making or finding rings or bungs each time you want to bore or turn your soft jaws why not simply use our Trueborer.

Read about Trueborer