Table saw kick-back is seperated into two categories: 1) straight line kickback: when the material is pushed against the blade without perpendicular resistance applied to the material between the blade and the fence. --materiel shoots like an arrow straight back. 2) back tooth kickback: when the material hits the back tooth of the blade and climbs up the blade, blade digs into material, flings the peice back, while rotating. --- piece shoots up at you. (More detailed info on kickback here: http://www.waterfrontwoods.com/Articles/Tablesaw/tablesaw.html#sthash.VSpQnDIR.dpuf [Broken]) Here is a video of what back-tooth kick-back looks like in slow motion: Now here comes the big question... in back tooth kickback, your material rotates as it flies up/back. I'm wondering to what degree a piece rotates in order to establish danger zones. I've only ever seen smaller sizered material kickback--but what if you had kickback with ten foot lumber? How large/where in relation to the blade would the danger zone be for flying lumber injury potential? The general assumption for woodworkers is that material always go back towards the operator no matter what, but having researched this I have doubts that it is based in fact. -If you want to narrow down some parameters... a delta unisaw is a common cab shop standard-- 3 hp, 10 inch blade. 4000 rpm. (http://www.deltamachinery.com/products/table-saws/item/36-l336?category_id=1) We can assume a typical specimen for a lumber unit could be a 10 x 5 x 7/8 alder beam weighing 20 pounds if you want. Please let me know if any other info is needed, or if my question isn't making sense. Thanks very much!