I have a question concerning the safety of stop blocks on the non-hand-held side of a blade. I know on a table saw, the stop block should end before the wood engages the blade to eliminate kickback, but how does this affect saws where the blade moves and the wood stays stationary-radial arm saw, miter saw and sliding miter saw? I’ve seen several pictures of stop block designs in woodworking magazines, and it appears that the authors thought there was no danger of kickback with these types of saws.
Rob Johnstone: True “kickback” is a situation where a rotating saw blade (or cutter of some sort) grabs or binds to a piece of material and throws or “kicks it back” opposite the direction that it is being pushed (i.e., towards the user). It is primarily a problem with a table saw (or in some cases a table-mounted router or shaper). This is very dangerous, as it can pull your fingers through the saw blade or even impale you with the material that is being thrown back at you.
Where you are moving the saw through the material with a radial arm saw or sliding miter saw as you described, if the material should bind the saw blade – with or without a stop block – the saw would be impelled toward the user. This is startling, but in most cases quite manageable. The material will be pushed or thrown away from the user (toward the fence). If the material is tight to the fence when you start your cut, then with a chop saw or the like, it is really not a dangerous thing. You must keep your off hand out of the path of the saw in any case, as is only common sense.