CNC machines, over years of use, can gradually wear down and lead to bad parts being manufactured. The ballbar test, when appropriately set up, carefully monitors the location of sensors on the ballbar within a created XY plane. Once it has been set up, executing a circular interpolation allows the device to accurately record how smooth or rough the actual circle being ‘cut’ is. Comparing this to an imaginary ‘perfect’ circle, one can visually notice quite a few potential defects on the machine.

This test can help detect and diagnose issues correlating to axis reversal spikes, scale mismatching, backlash, stick-slip, squareness, servo mismatches, cyclic errors, and even master/slave changeover errors. Periodically performing this test allows patterns to be noticed and observed, making it much easier to catch a drop in performance and fix the problem long before it becomes a catastrophic issue.

Generally speaking, in the harshest machine conditions, this test would not need to be performed more than once a week at the maximum. Every six months would be a good gap between tests depending on the daily amount of work being performed on the machine. The more the machine is used, the quicker it will wear down and potentially lead to some of these issues which the ballbar can detect.

A ballbar test can also be performed quite quickly. A standard XY plane test can be done in 15-30 minutes, mostly dependant on the user’s familiarity with the product and how to run the test. Of course, this can also get a bit lengthier when checking all XY, YZ, and XZ planes, but the overall results and defects that can be caught from doing so can often times bring a machine deemed as ‘scrap’ back to life and into production!

For any questions in regards to the ballbar test or other general inquiries, feel free to contact us by phone or email to get in touch with our experienced technical support team.

At Precision Zone, we guide our clients toward the best decisions that serve their business needs. If you have specific repair or replacement questions, get in touch with our expert customer support team at 800-551-4420 or

Written by:

Marketing & Creative Director at IcarTeam, and supporting afiliated businesses,
including Precision Zone, Precision Education Integrators and Alfra Tools.
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