Compound miter saw safety?

[Tamarack]

On some of the do-it-yourself shows I've watched, I've noticed that they let the blade come to a stop before lifting it out of the cut. I'm sure there must be a good reason for this but no-one has ever explained it to me. Can one of you more experienced people clear this up for me (and any others who don't know either) before I hurt something through my ignorance?

Paul in Idaho

[RayintheUK]

Because of the way CM saws are built, it is not possible to clear the workpiece entirely from the blade at the end of a cut (as it is with a tablesaw through-cut - either ripping or cross-cutting). If the workpiece was to move sideways - even a fraction - while the blade was still spinning, the rear of the blade may catch it - if it did, it would pick up the piece and project it upwards (as in kickback on a tablesaw). This could lead to damage to the saw, especially the blade guard, as well as personal injury to the operator. If making a non-through-cut on a tablesaw, you would wait for the blade to come to rest before withdrawing the stock. For similar reasons, this practice is also the safest on a CMS.

Another thing to watch for, when cutting with a CMS, is that both sides of the workpiece are adequately supported. If not, then any piece that overhangs the side support sufficiently will become unbalanced when the cut is completed, because the side support will become a fulcrum. The stock will become "see-saw"-like, rising the cut end into the spinning blade and blade guard. This, in my experience, is the most common cause of damage to CMS machines and their operators. HTH

Ray.

[ejs1097]

As Ray indicates, it's primarily a saftey issue. To add on what he siad, many times you use a stop with a CMS to cut mutliple pieces. Raising a spinning blade while using a stop further compounds (no pun intended) binding the work and causing an unsafe condition. The smaller the cutoff the more chance for it to fly back in your eye, etc.

I almost always wait for the blade to stop, on the times I don't is when I notice more blade markings and paint from the blade on the edge of the cut indicating I just effected the initial cut.

[LinuxRandal]

Because of the way CM saws are built, it is not possible to clear the workpiece entirely from the blade at the end of a cut (as it is with a tablesaw through-cut - either ripping or cross-cutting). If the workpiece was to move sideways - even a fraction - while the blade was still spinning, the rear of the blade may catch it - if it did, it would pick up the piece and project it upwards (as in kickback on a tablesaw). This could lead to damage to the saw, especially the blade guard, as well as personal injury to the operator. If making a non-through-cut on a tablesaw, you would wait for the blade to come to rest before withdrawing the stock. For similar reasons, this practice is also the safest on a CMS.

Another thing to watch for, when cutting with a CMS, is that both sides of the workpiece are adequately supported. If not, then any piece that overhangs the side support sufficiently will become unbalanced when the cut is completed, because the side support will become a fulcrum. The stock will become "see-saw"-like, rising the cut end into the spinning blade and blade guard. This, in my experience, is the most common cause of damage to CMS machines and their operators. HTH

Ray.

Let me add one thing. Years ago, when I first used one, I needed to trim off just a tiny piece, of a board that was the max width of the saw I was using. That tiny piece got jambed in between the blade and the ejection port, then recut and one piece stuck in the ejection (dust) port, and the other was slung into and broke the guard. Small cutoffs can be a problem.

[Tequila]

Small cutoffs can be a problem.

When I have to take a small cutoff, I usually try to inch up on it from the edge so that there's no small pieces left to do what you described. It takes a couple extra cuts, but there's no chance of small pieces of wood flying back out at you.

[scorrpio]

I'd always stop the blade before rising it back. Blade body is thinner than teeth, so either piece shifting slightly should not be a problem - and even if it touches blade body, a lot less chance it will get hooked and flung. Moving the still-spinning teeth back through just made kerf, on the other hand, is asking for trouble. A small shift on either piece, and you'll either mar your cut or get kickback.