Similar to When is it not possible or not practical to use a blade guard?, what types of cuts require the riving knife (and blade guard) to be removed?
Although there are many instances in which you need to remove a standard or modular table saw blade guard, most cuts can be made with a riving knife installed. However, there are a few operations for which you must (or should) remove the riving knife:
- Raising the blade through a workpiece (e.g., when cutting the slot for a crosscut sled or zero-clearance insert)
- Using a dado stack (the riving knife does not perform its duty and, in fact, will probably block your workpiece; for example, if installing an 8" or 6" dado stack along with a riving knife intended for a 10" blade)
- Cutting coves
Also keep in mind that your riving knife must be approximately the same thickness as your blade. If you use a standard-kerf riving knife with a thin-kerf blade, your workpiece may be blocked by the riving knife or may pinch it, or may be pinched between the riving knife and fence. Conversely, if you use a thin-kerf riving knife with a standard-kerf blade, your riving knife will not be as effective at preventing kickback.
The riving knife on my table saw (Powermatic 2000) extends higher than the blade. This is because it also functions as the mount for the blade guard which I no longer use since I have come to appreciate the safety factor of the riving knife.
It is necessary to remove the riving knife whenever I make any cut that is not a through cut, i.e. a groove. I have frequently thought, though not acted yet, to hacking off the riving knife so that its top is even with the top of the blade.