Making safe cuts: Sliding miter saw vs Radial-arm saw

Question

In multiple questions (this is one) having to do with sliding miter saws, we have been admonished how to correctly make cuts - to wit: with the motor off, pull the saw outward, push the saw down, turn on the motor, push the saw forward, turn off the motor. This is described as the safe way and even shows up in instructions provided by manufacturers.

Now, when I use my radial arm saw, I pretty much do the opposite, to wit: setup the cut, turn on the motor, pull the saw outward, push the saw back, turn off the motor. I think this is the safe way to do it - have made thousands of cuts without mishap and I'm sure it's the accepted procedure.

So my question is: why is the safe way to make the miter saw cut to push, and for the radial arm saw to pull?

In both cases the blade is turning the same direction and on both saws the cut board is against a fence.

Answer 1

You are, indeed, using your radial arm saw correctly, but it's important to note the critical differences between the two tools.

In both cases, you would be making a climb cut when pulling the blade toward you. A climb cut is generally less safe because the blade literally tries to "climb" over the wood as it pulls itself into and over the wood. If you are not used to using a radial arm saw, it can be difficult to control and can pull itself toward you faster than you may expect, especially if the blade's teeth have a positive hook.

Using a blade with a negative hook angle makes a climb cut easier to control.

So my question is: why is the safe way to make the miter saw cut to push, and for the radial arm saw to pull?

Let's start with the second part of that question--simply put, it is impractical to use the radial arm saw any other way. First, you cannot easily raise the blade over the workpiece. Second, it pushes the workpiece down into the table. The blade's ability to climb over the workpiece is limited by the fact that the blade's height cannot be raised accidentally in the middle of a cut on a properly set up saw. To make a cut with a radial arm saw by pushing the blade instead of pulling it toward you, you would need to pull the blade toward you, position your workpiece behind it, and clamp the workpiece down (to prevent the saw from potentially lifting it off the table).

In contrast, a sliding miter saw does have the ability to raise the blade over your workpiece. However, it does not have any feature to lock its blade down at a fixed height, allowing it even more climbing ability if used to make a climb cut rather than following the recommended procedure.

Answer 2

I believe that the problem appears with the introduction of the sliding capability. If—in the cutting motion—the saw blade merely tilts, the forces onto the piece are always down/or to the fence, hence there is no force trying to lift the piece (on square cuts). Instead, when cutting a wide piece- as wide as allowed by the sliding stroke, and the saw is pushed back - the resulting force onto the piece might result being upwards which might be quite dangerous. For those reasons:

1. The sliding motion is a limited fraction of the blade diameter

2. The saw manufacturer ask you to always block down the piece

It's very clear that a sliding saw should be used in a pulling motion after it has been tilted in the rear position. At the end of the tilting stroke, a trigger stop should keep the saw at the dawn position, when the pulling motion begins, then the saw behavior should be identical to that of a radial arm saw.

The problem is that, for real safety you will need that that trigger stop, should additionally block the pulling motion if the saw didn't reach its lower position.

But it happens that this trigger stop has not (yet) been incorporated, hence by limiting the ratio sliding stroke to blade diameter a reasonable safety compromise has been reached. Beyond that, it is better to clamp the piece while pushing for cross cutting.

Answer 3

I realise this is an old post but wish to add my threepeneth! As a member of a thriving men’s shed, many of our members have had a nasty fright when cutting cladding boards on a sliding mitre saw and NOT making sure to have the convex edge of a warped board firmly against the fence. When pushing the cutting blade back the kerf closes up and the blade snatches. We even had a machine break at the main support - wrecked. When the blade snatches, the impact is also liable to bend the fence thus ensuring that there will always be a gap to cause future trouble. You can’t straighten out the fence as they are cast aluminium. I have recently realised that if one starts the cut at the back and pulls the blade out there is NO risk of snatching. I have done this many times now with no problems whatsoever! If anyone can genuinely claim that they have had a problem with the blade ‘climbing’ over the workpiece by doing what I suggest rather than just implying that it might be a problem then I might reconsider. Otherwise I maintain this is the safest method!