Hey all you router mavens.....

[Bill White]

Any of you tried a "compression" router bit when routing rebates or dados?
I've seen them used on cnc machines (clean entry and exit edges), and thought that they might be worthy for pattern cutting and plunge cutting.
Bill

[Bill Hylton]

Compression bits are primarily used for cutting up man-made sheets--hardwood plywood, melamine-coated particleboard, laminate-covered substrates. Because the cutting edges spiral both up and down, you get crisp, chip-free edges to the cut on both top and bottom.

I've used a compression bit in a 2-hp router to break down 3/4" plywood sheets, rather than a circular saw. The kerf is wider than a saw's, but you don't have to recut each panel to trim off the splintered edges.

For routing dadoes with crisp edges, use a short bit with downshear cutting edges. Just 3 deg. of downshear makes a big difference. Such bits aren't necessarily common, but you can find them in more diameters than compression bits, and for a lot less money.

Bill