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I'm barely a novice carpenter, in fact all the wood work that I do is for my college's technical theater program, but I'm handy with saws, and other power tools.

I've been told by many people I work with that I should never cut more than one piece of wood on the miter saw at a time. I think this is ridiculous. When I ask them to explain how its more dangerous, nobody has a good answer.

It seems to me that if I need two pieces of identical length, I should cut them at the same time. If they're small enough, maybe three in one cut.

So my question to you all: Is it dangerous to cut multiple pieces of wood on a miter saw in one cut? What about other powered saws?

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    Using a stop block is another way to get pieces of identical length - especially if you need more than will fit on your miter saw at once. – mmathis Mar 16 '17 at 18:57
  • True, I've used stop blocks before and they do their job. I only used length as an example, but I can think of more reasons one might want to cut multiple pieces at once. Say I've got to cut 40 legs for a platform. I'd much rather use a stop block for length, then make 20 cuts rather than 40. – Adam Schiavone Mar 16 '17 at 19:01
  • The one safe or semi-safe way that I've seen multiples cut in one go is to tape the boards together and then cut, something done not infrequently on the bandsaw. Presumably this same thing could be done in certain circumstances with other power saws but I don't recall ever seeing it. Note that there must be tape on both sides of the cut so that the ganged boards as much as possible act like a single piece of wood. But saying that, for simple end cuts fixing up a stop block and then sawing individually is sure to work out faster. – Graphus Mar 17 '17 at 0:33
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There are a couple main (safety) concerns with this: the pieces moving while cutting and the offcuts getting caught in the blade.

Pieces moving while cutting

This is not so much an issue with safety as it is with accuracy. If one (or all) of the pieces move, you'll need to redo the cut on at least one of the boards, potentially negating any time savings you would see by cutting multiple pieces at once. Risk is negligible if everything is clamped.

Offcuts getting caught in the blade

This is probably not as much an issue on a miter saw as it is on other powered saws. Offcuts always have a change to get caught in the blade, although this situation is riskier since you are continuing to cut after an offcut is made. Typically, your offcut would become free at the end of the cut, at which point you turn off the saw. In this case, though, you are continuing to cut, so you have to be aware of what those offcuts are doing (and where your board is pushing them). With a miter saw, the blade is probably moving away from the offcuts, so likely not a big risk. Clamping again can reduce this (clamp both the "keep" side and the offcut side), but does introduce a potential problem with binding.

Thanks to @JacobEdmond for pointing out that stacking the pieces vertically on a miter saw can lead to the offcuts falling into the blade. Positioning the pieces in front of each other leads to a much safer cut.

For the same reason you don't want to run a piece in a crosscut sled against the fence (use an offset fence instead), you want to be careful about confining the pieces too much after the cut. You don't want the offcuts to get caught in the blade, but a loose offcut in the blade is much better than an offcut which is confined - that leads to flying wood and other Bad Things.

Your bigger issue is likely to be accuracy

Getting 2 (or 3 or more) boards lined up exactly together, with a stop block, clamp, or other registration device, is likely to take a relatively long time in order to make an accurate cut. More time, likely, than just setting up a stop block and making 40 "single" cuts instead of 20 "double" cuts in the first place. In addition (thanks again to @JacobEdmond), any error in your miter saw setup (blade angle, bevel angle, etc) will be amplified across the bigger cut.

Consider the time to line up the pieces, put a clamp on, butt up against the stop block (or measure with a tape and mark), ensure the pieces are still lined up, and cut. Compare that to the time to butt the piece up against the stop block and cut.

So, while it can be done relatively safely, it may not gain you much in terms of speed - unless your tolerances are fairly loose.

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  • We must have been typing at the same time. You give a more thorough explanation of most of the same points I made so I gave you a vote. Only additional comments I had were about the accuracy likely being worse the more you stack up or out, and the added safety of layering out from the fence instead of stacking up. – Jacob Edmond Mar 16 '17 at 19:32
  • This is the first explanation I've heard that makes sense. I never thought too much about the offcut getting caught. Thank you. – Adam Schiavone Mar 16 '17 at 19:35
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    @JacobEdmond Yeah, we must have been. I incorporated those points of your answer into mine, hope you don't mind :) – mmathis Mar 16 '17 at 19:56
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It really depends on the pieces and situation, but the risk in my experience ultimately comes from the falloff of the cut.

I would never stack multiple pieces vertically on the miter saw, as the top pieces will be cut through first, and those pieces of falloff will likely move before you finish you cut and can get thrown or possible pulled back into the blade.

The only way I might cut multiple pieces is one in front of the other standing on edge, so the widest dimension of the first part is against the fence, and the second part is oriented the same but in front of the first part. This way I can cut through them both and the falloff of each part will come loose approximately the same time, or in order of front the back.

As far as accuracy goes, the reality is you are better off cutting one part at a time with a stop block. If your miter saw is out of plumb or square any minute amount, this will only be amplified by stacking or layering parts front to back, so each part will be off more and more the further it is away from either the fence or from the table.

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Stacked cutting is verboten in my shop. It isn't so much that it is dangerous in every instance, but shortcutting is a horrible habit when you are dealing with sharp and pointy things.

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I do it continuously, with usually as many boards as the blade has capacity to cut at once, never any issues with binding or off cuts. I'm not sure about accuracy because my work isn't that precise if the cut is off an 1/8" or beveled a few degrees I don't notice.

I'm sure there's increased wear on the saw and blade... but then again there's increased wear every time you plug it in, in my opinion do whatever you prefer and makes the job go by easier/more enjoyable there's no serious danger either way.

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