Error of three roller bending machine:
1. the two end face of the workpiece is not perpendicular to the hole, and the ends of the workpiece are not parallel (when several workpieces are milling or cutting), or the ends of the pressure ring are not parallel.
2. spindle itself is error
3. when using the rolling machines top processing, the lower center is partial pendulum or loose, in the clamping ring clamp, in the side of the pendulum deviation
4. three roller bending machine the bore of the workpiece is greater than the diameter of the spindle (usually D/a)