On mouldings with a profile, base, cases, etc, what is the best way for the back side relief profile? Many half moon cuts, one big relief cut, two, or many small slots?
(Solid Wood Machining Forum)
From contributor D:
The main reason for relieved backs on such moldings is to ensure that the visible edges of the moldings stay tight against the surface they're nailed to, even if the molding cups outward a bit. Any method that leaves parts of the molding towards the middle untouched (i.e. slots, half moon cuts, etc.) won't achieve this. You're looking for a wide, shallow recess.
The second two pockets use to change out three sets of relief cutters. I say three sets because I have always used three sets, different widths, this technique works for just about everything. The straight knives produce the finish on the bottom face, the relief cutters should be set 1/16" to 3/32" higher than the straight knives to leave the proper relief. It would be nice to make individual sets for different profiles with just two knives, but no one I know does it, too costly.