Okuma Rotary Table & Trunnion Calibration

What Is Rotary Table & Trunnion Calibration?

A 5-axis machine adds two rotational axes to the standard X, Y, Z linear travel — typically an A-axis that tilts and a C-axis that rotates the table or trunnion. These axes let the machine reach undercuts and complex geometry a 3-axis machine can't touch, but they also introduce their own error sources that standard linear calibration was never designed to catch. A machine can pass a ballbar and laser interferometer check with excellent linear positioning and still cut inaccurate parts the moment a rotary axis gets involved.

We measure rotary axis accuracy with a dedicated angular calibrator working alongside a laser interferometer, verifying angular positioning to within about one arc second. A-axis misalignment tends to show up as positional error in the Y-Z plane; C-axis inaccuracies tend to show up as errors in circular interpolation. Both eventually affect tool center point — the actual point in space where the cutting edge is supposed to be — which is what your 5-axis toolpaths are built around.

We are an independent repair company. We are not an authorized Okuma dealer, distributor or service partner — we calibrate and verify Okuma 5-axis machines on customer-owned equipment.

Trunnion-style tables, where both rotary axes tilt and rotate the workpiece together, give excellent undercut access and rigidity for small-to-medium parts, but the physical risers involved make alignment drift a real possibility after a crash or bearing service. Annual calibration is a reasonable baseline; high-utilization machines are better served by condition-based checks — after any crash, after rotary bearing work, or whenever angled-cut accuracy starts drifting.