Table saws: is kickback feasible with a riving knife?

[sploo]

No it looks like a really cra p idea. The disadvantages of both.
Just stick to simple push sticks like heimlaga's above.

PS the worst aspect of that utterly stupid american push-stick is that you hand and forearm are well over or past the blade before the end of the workpiece! Ferkin dangerous!
With sensible push sticks you are always well away.

Well, my original idea was essentially a push stick with a push block on the end (the advantage of distance, but with some of the advantages of being able to apply a degree of downwards and sideways pressure).

I'll grant you that the "over the blade" issue is a big problem with that design, but if you do have a guard over the top, and the handle were, say, at least 6" from the table surface it might be OK.

Sploo, I glued fine sandpaper onto my push sticks, they grip the wood but don't mark it.

Ah yes - as per lots of Niki's jigs. Yes, that would be a good idea too.

 

[pcb1962]

What is commonly known as 'kick-back' is when the timber contacts the rear rising teeth, the timber is then lifted which brings it into contact the topmost teeth which are spinning towards you this then causes it to be very violently thrown forward and to the left

like this: http://youtu.be/u7sRrC2Jpp4?t=2m29s

 

[andersonec]

What is commonly known as 'kick-back' is when the timber contacts the rear rising teeth, the timber is then lifted which brings it into contact the topmost teeth which are spinning towards you this then causes it to be very violently thrown forward and to the left

like this: http://youtu.be/u7sRrC2Jpp4?t=2m29s

As soon as that one started I switched it off again, I think I know what's going to happen when I saw his hand going past the teeth of the saw blade,,,does the wood drag his hand in as well??

Andy

 

[pcb1962]

What is commonly known as 'kick-back' is when the timber contacts the rear rising teeth, the timber is then lifted which brings it into contact the topmost teeth which are spinning towards you this then causes it to be very violently thrown forward and to the left

like this:

As soon as that one started I switched it off again, I think I know what's going to happen when I saw his hand going past the teeth of the saw blade,,,does the wood drag his hand in as well??

Andy

Comes close, but not quite. Well worth watching the whole video, shows how the trajectory of the timber is not what you'd expect.

 

[DiscoStu]

Wow! Great video for showing the dangers. His hand comes very close to the blade in the table saw demo. Oddly I've been having issues with my Riving knife and I was thinking that I might just remove it. That idea is now firmly out f my head!

 

[Jacob]

What is commonly known as 'kick-back' is when the timber contacts the rear rising teeth, the timber is then lifted which brings it into contact the topmost teeth which are spinning towards you this then causes it to be very violently thrown forward and to the left

like this: http://youtu.be/u7sRrC2Jpp4?t=2m29s

I just watched it :shock:
The stupid yank seemed to have missed the most important lesson of all - that those push blocks are extremely clumsy, pointless and ineffective.
The possibility of harm from the flying wood was far less than the risk of losing a finger.
They give an illusion of safety (to an inexperienced beginner) but actually increase the danger as they encourage the user to have the whole hand close to the blade. They they don't even hold the wood firmly AND you have to over-reach the blade, effectively shortening your reach. It'd probably be safer without them at all (though I wouldn't try it!)

With two push sticks he'd have had much better control, no over-reaching, with much less risk, even without the riving knife.

All the push blocks I've seen are similarly stupid - basically a really bad idea.

PS to put it another way - this video is less about the relatively trivial danger of kickback; it's more about the danger of using push blocks.
HSE reports emphasise the risk of coming into contact with cutters as the biggest cause of injury.

PPS I don't get kick back except the first time I tried to cut a bevel edge - the wedge section off-cut can get lifted and jammed between blade and fence and slung out at speed. I've done it thousands of times since, but with a false fence designed to allow the off-cut to fall free.
With normal cutting you can often tell the approach of a kick-back prob - the workpiece gets harder to push as it starts to grip. The answer is to back it off the blade carefully and try again. This is where push sticks really help - you can hold the stuff down and in, as you pull it back.