different types of freehand ground router bits, and their application.
Many types of wood and wood machining require bit geometry that is not
available off the shelf.  For contour work (radius, etc) a neutral or 
even negative rake is preferable, to eliminate tearout.  With a French
Headstyle bit body (slotted body) a flat bit gorund to profile, will 
be very slightly negative rake.  HSS bits (5/32" planer knife steel)
can be gorund sharp enough to do a smooth job with reasonable durability.
Useful in custom and repro work.