Simplifying the task of jaw placement on three-jaw chucks

Simplifying the task of jaw placement on three-jaw chucks

Most three-jaw chucks used on turning centers have a series of fine serrations on master jaws and top tooling that must be properly aligned when top tooling is mounted to the chuck. But by the nature of three-jaw chucks (jaws are 120 degrees apart), it can be difficult - if not impossible - to determine the exact diameter at which each jaw is being placed in the chuck.
In addition, the fine serrations of the master jaw and top tooling make it very difficult to align all three jaws in the same series of serrations. Most setup people count the number of serrations on the master jaw in order to get each jaw into the correct serration. But time-consuming mistakes are often made.
If jaws are not properly aligned, of course, they will not run true when the spindle is started. Fortunately, this will be very obvious to the setup person. But the jaws must be removed and the entire task of jaw placement must be repeated. It is not uncommon for entry-level setup people to make several attempts before jaws are properly aligned and at the correct diameter in the chuck.
Some chucks have concentric circles scribed on the chuck face to help - but even with these chucks, jaw placement can be time consuming, error prone, and difficult - especially for entry-level setup people.
Jaw placement time directly affects setup time. The CNC turning center must, of course, be down while jaws are being mounted to the chuck. Anything you do to reduce jaw mounting time will, in turn, reduce setup time.

What about the chucking plug or ring?

After correct mounting to the chuck, soft jaws must often be turned or bored. The chuck must be activated (opened or closed), and the jaws must be clamped on a chucking plug or ring. Most chuck manufacturers recommend that this clamping take place about half way through the chuck jaw's stroke. And clamping pressure should be set the same as it will be for production machining.
Even determining what diameter plug or ring must be used can be difficult. Again, the jaws on three-jaw chucks are mounted 120 degrees apart, making it impossible to use standard measuring tools (scales, calipers, etc.) to determine the diameter at which jaws will be clamped half-way through their stroke (unless pie-jaws are being used). Most setup people use trial-and-error to find the correct diameter chucking plug or ring. While experience setup people may often do so on the first try, entry-level setup people may require several time-consuming attempts.

One great solution

These three problems - properly aligning all three jaws, getting them at the proper diameter, and determining what diameter chucking plug or ring must be used - are all easily solved with a new product manufactured by CNC Consulting and Training and now distributed by CNC Concepts, Inc. The Laser Jaw Setter (patent applied for). With the Laser Jaw Setter, your setup people will know in which serration each jaw should be mounted, the diameter at which the jaws will be, and they'll be able to easily determine the diameter of the chucking plug or ring needed for machining soft jaws. And of course, these three improvements reduce the time needed to mount and machine jaws -simplifying the task along the way. The obvious result is reduced setup time.