Right on, Jim. It leads to quadratic equations and Pythagoras. I had tried to take a generalized approach with construction. Thanks.
That's too pessimistic. The apparent feed size error drops rapidly with workpiece size and is normally negligible.
With 0.005" height error simple Pythagoras shows
workpiece size Apparent feed error % of Height 0.1" 0.00025" 5% 1.0" 0.000025" 0.5% 10" 0.0000025" 0.05%
Jim