Question for SawStop owners

[Roy G]

I have been following the thread about getting a new table saw and saw that a lot of people were sold on the safety of the SawStop. I have an old Unisaw that has served me well and only given me a slight nick once. My question concerns kick-back. When I was ripping a strip off a screen-door, the cut-off got trapped against the fence and shot out into the shop. I was not injured but the plywood door of my tool cabinet was punctured by the cut-off. So a strip of pine was shot through a 1/4" thick plywood door. Would the SawStop have prevented this?

Roy G

 

[Jeremy Scuteri]

SawStop's blade braking technology does not prevent kickback.

 

[ehpoole]

I am not a SawStop owner but the question is simple enough to answer.

A SawStop tablesaw will NOT detect or prevent kickback or kickback related injuries. The SawStop works by detecting a small flow of electrical current between the metal blade and the metal tablesaw top, completing an electrical circuit that trips the pyrotechnics in the blade cartridge and retracts the blade (your body is electrically conductive, but this is also why the safety mechanism must be disabled when sawing wet wood and metal). An expensive event when it happens (you must replace the blade and cartridge afterwards), but much cheaper than the alternative trip to your local hospital!

Kickback is caused by either of two events: 1) an object being dropped on top of the moving saw blade and being accelerated by the spinning blade towards the user, or 2) the workpiece becoming trapped or pinched against either side of the blade (such as when trapped between blade and fence, case hardened wood, or reaction wood pinching closed or outwards against the fence) which causes the workpiece to ride up the rear of the blade resulting in the workpiece being accelerated quickly towards the user.

However, all modern (recent year) tablesaws now include riving knives that should always be left installed on the tablesaw (there is no good reason to remove them) and will greatly reduce the risk of kickback events by preventing the workpiece from pinching the rear of the saw blade. Additionally, for general sawing you may elect to install the larger riving knife that includes a blade guard and anti-kickback pawls to reduce the kickback risk even further. This is true of SawStops and all other legitimate tablesaw brands on the market today, but was not the norm more than a few years ago. So any new tablesaw, provided the riving knife is kept installed at all times, should greatly reduce the kickback risk versus an older tablesaw without a riving knife (or even a decent splitter installed). But even an older tablesaw can be made much safer if you simply ensure that a splitter, appropriate for your blade width, is installed at all times. Unfortunately, a ring knife is not a practical upgrade for older tablesaws as the riving knife must track up and down in coordination with the saw blade (and is attached to the actual trunnions assembly) whereas the old splitter and blade guard assembly was a fixed position install so be can not simply be installed as a substitute for another.

The above said, even most older saws (back to the 70s, if not earlier) ordinarily shipped with an integrated blade guard, splitter, and anti-kickback pawls setup that can be installed whenever making the sort of cuts that are at greatest risk of kickback (namely large sheet goods and ripping operations), though many of us regularly operate without such installed. I am in that group but I do install it whenever I am making a cut where there is an elevated risk of kickback occurring. I also make use of featherboards when ripping, for example, to greatly reduce the risk of kickback by denying the workpiece the opportunity to get out of line or ride up over the blade, which largely eliminates the risk of kickback occurring.

 

[Berta]

That is the reason you never put the off cut between the fence and the blade.

 

[tarheelz]

All the above is true, however, consider this:

The blade guard setup is well designed on the SawStop. As such, I leave it on most of the time for rips. This gives me the pawl (two levels) and riving knife protection against kickbacks.

For cuts where I cannot use the blade guard (crosscuts sled, partial thickness, super thin cuts), the SawStop needs only a couple of secs to switch from the blade guard to a stand alone riving knife.

Final note: The stock fence of the SawStop is very reliable and adjustable.

SO... While the SawStop braking technology is no help, I would argue that the overall design of the SawStop does, in fact, reduce risk of kickbacks.

 

[Mark Johnson]

I would add that the Hammer saw also has very significant design elements that help prevent kickback even beyond the sliding table which eliminates the need for cross cut sleds. The fence design allows a set up that greatly reduces the opportunity for the "pinch" that causes kickback, and of course it has the splitter/rivingknife as well. If you are looking at a new saw, you really should at least look at one.

 

[FlyingRon]

It's not really a flow of current to the table. There's no requirement that you be in contact with the table to fire the mechanism. My guess is the contact with the blade detunes an RF circuit similar to the way the 'touch sensor' lights work.

I agree the riving knife has saved my bacon more times than the flesh sensor. I get much less kickback issues when I switched to the SS from my "pre-riving knife" Delta.