Lathe Chuck Jaw Boring Technique

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FORMING SOFT JAWS (SOFT JAW BORING TECHNIQUE)

• To hold components of different diameters, the soft jaws are moved radially outward or inward and bored in position to ensure that the workpiece is held properly 
• The inner profile of the soft jaw bore should be matched to the outer profile of the component
• It is very important that the component is clamped in the mid stroke of the jaws

Please take a few minutes to read this to ensure that jaw play is reduced to maintain the consistency in the machined batch of the components.

Step 1:

Prepare a suitable ring with sufficient wall thickness

Since clamping diameters vary, it is necessary to produce different rings and ensure that the ring is strong enough to withstand clamping pressures without deforming

Step 2:

Open the jaws fully (de-clamp) by actuating the cylinder / actuator.

Then turn the soft jaw with diameter (D) equal to ring outside diameter +1/2 jaw stroke.
D = (d+1/2 Jaw stroke)

This step ensures clamping in mid stroke

Step 3:

Grip the prepared ring in the soft jaw prepared as in Step 2. Ensure  that the ring butts against the chuck face.

This is the actual step to ensure that the play is reduced to maintain the consistency in the machined batch of the components.  

Turn the soft jaw to the  the component gripping diameter with a good surface finish.

 D1 should be equal to the diameter of component to be turned after jaw boring. The entry of component should be to (H7/H6)  sliding fit.

While turning the soft jaw, the clamping pressure setting should be as same as required for clamping the component.

After turning the soft jaw, clamp the component and check the jaw stroke and gripping accuracy in the component.

Take a trial cut and check the machining accuracy.

For checking the jaw seating of the component, remove component, rotate to 90 degrees, clamp once again and check end face for true running.