Many of us use a drag knife on occasion, but few know about one of the built in features of the WinCNC Controller, Tangential Knife Control.
Here is a 5 minute video showing my first cuts on a tangential knife that I built. It uses standard sized utility knife blades, but I am using the higher priced Lenox Carbide Blades. It looks like speeds can be increased and still retain quality, at least in the double ply corrugated and Coroplast that I had on hand for the test cuts.
Toolpaths are generated with VCarve Pro using a "WinCNC Knife" post processor. Earlier versions used a stepper motor, but they were losing steps due to the "bursts of pulses" that occur going around circles.