A spiral down cut has blades which forces chips down back into your material. This has benefits of providing a perfect top finish to any wood type especially plys and top finishes. Made of a very high tungsten carbide material, down cut bits are the a weapon of choice in anyone's arsenal. Opposite to a spiral up cut, a down cut will give you a perfect top finish but a burred bottom finish if cutting all the way through. These bits therefore are most effective for engraving & lettering rather than cutting all the way through.
- Wood (MDF, hardwood, ply & softwoods)
Just like a straight flute, a down cut creates a lot of dust as opposed to chips so make sure you have appropriate ventilation or dust extraction when cutting. On the plus side, the dust gets stuck and packed back into the slot you have made and keeps your cut item in place. This has the advantage of not having to use tabs or tape to hold your material down although can add time back in with the need to deburr the bottom edge.