Dado safety?

[Jamie Buxton]

For years I've been reading comments about the safety of European table saw. The posters cite riving knives, and the lack of dado heads as evidence that European saws are safer. Riving knives I understand. They are indeed better. But the part I don't understand is the dado heads. What exactly is so dangerous about dado heads? I ask this not to start a fight, but rather to try to understand where the dangers are in my shop. Safety starts by understanding the dangers.

[Mark Marzluf]

The thought (as I understand it) is that a dado stack obviously creates a wider cutting path. A dado stack allows the saw to grab a whole bunch more of the wood and thereby increases the posability for kickback. Like putting slicks on a dragster... the more surface area you can apply torque to - the easier it is to lauch the vehicle off the line. Know what I mean?

[Steve Wargo]

Jamie,
Dado heads are only dangerous if you get too comfortable with them. I've had three table saw incedents. Nothing too major, but two of them were accidents with dado blades, and both of them resulted in a broken thumb. The last one was broken in three places. It all boils down to the fact that my fingers simply aren't stronger than a 3HP Unisaw motor. Needless to say, I don't have a table saw anymore. Probably the right choice for me.

[Jay Knepper]

I had the same question. I believe that the answer is an EU requirement that blades stop spinning within something like 10 seconds. This is tough to do with the extra inertia of a dado set.

[Ian Barley]

There are a number of reasons why dado heads are not implemented on EU spec table saws.

1 - It is more difficult to implement guarding of the blade when making a dado cut. This is especially true where, as is the case with most euro spec saws, the guard is mounted on a riving knife. You just cannot make a partial depth cut like a dado with a knife mounted guard in place.

2 - There is indeed a requirement that workplace tooling that is manually accessible comes to rest within 10 seconds of power off. This is usually achieved with DC injection braking. The inertia in a dado blade means that there is a risk of blade detachment if that amount of "reverse thrust" is applied to a heavy spinning dado set.

Safety requirements on tools over here arise as a result of analysis of actual reported workplace accidents. The number of tablesaw accidents which occurred during dado cuts was disproportionately high compared to the actual use of TS to cut dadoes and a suitable alternative method exists (router etc). Therefore the standards for the EC certification, required on workplace tools, make it impractical to fit a dado by reducing the length of the blade spindle.

[Tom Hintz]

While I understand the European ban on dado stacks, I guess I am not to the point of actually getting behind it.
It is obvious though that in this part of the world, dado heads are not totally respected for thier capability to induce kickbacks. I frequently see forum postings telling new woodworkers that it is OK to use a miter gauge and rip fence together because the dado does not go all the way through the wood so therefore, it cannot cause a kickback. There are lots of people with bent, broken and mangled fingers who can testify to the contrary. If the teeth are engaged in wood, it can kick back.
I also see people pushing a board over a stacked dado with their bare hand, again because the dado is buried in the wood. If pushing something as inconsistent as wood over a spinning set of cutters 1/4" or so beneath the surface does not sound dangerous, I think those operators need to re-evaluate their concept of danger.
I use stacked dados all the time and have never had an injury incident with them. I do treat them with the respect they demand, take my time and pay attention. I also use good push blocks or push handles "just in case".

[Nissim Avrahami]

Hi from across the pond

The answer is very simple.

“Any operation without the saw blade guard is prohibited”. EU safety regulations.

To imply it, all the EU saws are made with short arbor.

The EU safety regulations are very strict, I heard that in some town in UK the firefighters cannot slide down on this tube.

I think that you call them “cicy's” in USA.

Regards
niki