These parameters allow you to adjust the feedrates of arc moves for 2 ½D milling features. The concept is that by slowing the feedrate on internal arcs and increasing the feedrate on external arcs, you get a more consistent finish.
Display this dialog box by clicking on the Peripheral feed … button in the Misc. tab of the Default Attributes.
Click the Decrease feed on internal arcs checkbox to slow down on concave moves. Set the lower limit by entering a percentage of the linear feed.
Click the Increase feed on external arcs checkbox to speed up on convex moves. Set the upper limit by entering a percentage of the linear feed.
There is a section for roughing and finishing and the options are identical. The finishing section applies to semi-finishing and finishing 2 ½ D milling operations. The roughing section applies to 2 ½ D roughing operations.
It is recommended to use these adjustments for finishing and leave the settings for roughing unchecked. Use feed optimization for roughing instead. In earlier versions of FeatureCAM, this functionality was called corner feedrate reduction and only allowed you to slow down concave corners.