Safety at Your Table

[fiatben]

I'm thinking that making a "double" featherboard so that one sits on either side of the blade would be great. It would keep the board flat on the table while not interfering with it past the cut. I can envision it being adjustable to accomodate dadoes and fastened to the fence so as to adjust how much in front of the blade's center it might sit.
Just a thought that popped into my head while reading this and looking at the pic.

[JPG]

Ed: The 'secret' to farmers holding firmly, is that by doing so, the workpiece doesn't 'start going south'. Add to that the fact that he knows when the workpiece will not cooperate. Back to the 'pay attention to what yer doin!'.

I have the opposite 'problem'. I tend to be too gentle when handling things and they tend to 'get away'. When a problem is anticipated, I will clamp down.

[foxtrapper]

While I agree with the poll question about a featherboard and splitter greatly reducing the incidence of kickback, I do not believe kickback is the result only of kerf closure or material riding up on the blade.

Something missing in this thread is the change in blade depth practice to reduce kickback. For some time the practice was to have the blade just outo f the wood surface, which maximized launch leverage. Later (and much earlier) the practice is to have the blade well clear of the wood, minimizing launch or kickback leverage.

[dusty]

While I agree with the poll question about a featherboard and splitter greatly reducing the incidence of kickback, I do not believe kickback is the result only of kerf closure or material riding up on the blade.

Something missing in this thread is the change in blade depth practice to reduce kickback. For some time the practice was to have the blade just outo f the wood surface, which maximized launch leverage. Later (and much earlier) the practice is to have the blade well clear of the wood, minimizing launch or kickback leverage.

I don't believe I understand the theory here. Is it your hypothesis that if the blade is raised so as to be well above the material being cut there is less chance of kickback?

I have just never related blade height to kickback potential. I lower the blade to just above the upper surface of the board mostly to reduce the amount of blade exposure.

My belief is that if the board remains on the table, the only thing that causes kickback is the blade being squeezed in the kerf. The only force tending to lift the board is the upward motion of the teeth on the back side of the blade. The splitter serves to reduce the likelyhood of the kerf closing thus reducing the probability of kickback.

The kickback pawls don't really come into play until s*** happens. Though the pawls do maintain some minimal downward pressure of the board.

Using featherboards serves only the purpose of holding the board down on the table as the teeth travel upward on the back side of the blade. The only force lifting the board is minimal until the board has lifted enough to climb up on top on the blade. Once that happens, it is normally too late to compensate. This is a case where prevention is salvation.

My approach: Use a splitter and featherboards and you will avoid the hazards of kickback.

[dlbristol]

Dusty said it well, I use all of them if I can. I operate under the theory that " Just cause you are paranoid, don't mean they ain't after ya!" I have never had a bad kick back, but I saw one once and it got my attention.

[JPG]

After giving the higher blade positioning a little thought, I believe the following:

If the blade is higher, the motion of the blade at the cutting face is more of a downward direction than if the blade just clears the top of the workpiece.

Since the top of the blade is much higher than the top of the workpiece, the workpiece must 'climb' much higher than if the top of the blade was just above the top of the workpiece.

If we 'assume' that kickback occurs if the workpiece climbs on top of the blade, then the situation is improved by increasing the blade height above the top if the workpiece.

However, I think that assumption is an over simplification of how/why kick backs occur.

I believe kickback occurs when the workpiece is 'caught' by the blade. This 'catching' can be caused by both/either the workpiece closing in on the blade due to warping pressure relief or the workpiece getting wedged between the blade and the fence(or a poorly positioned 'stop'). This 'catching' occurs at the back side of the blade and does cause the workpiece to raise towards the top of the blade.

However I believe the catching is the problem, not the raising of the workpiece towards the top of the blade. It is true, that the catching becomes kickback once the workpiece does rise to the top of the blade. This is what propels the workpiece back to from whence it came!

I am not sure that raising the blade will help prevent kickback. It may make it worse when it does happen?????

My gut feeling is that the lower blade position is preferable as it minimizes a different hazard.

In any event, prevention of the condition(s) which contribute to kickback occurring is what really 'works'.

[pennview]

Some other things that come to mind regarding kickback.

An improperly aligned saw--where the fence is closer to the blade in the back than in the front-- will pinch the wood.

A dull blade.

Warped, twisted, cupped boards, and trying to rip a board that doesn't have a straight edge can introduce binding along the way.

Small saw tables and fences are problematic because there is limited room in front of the blade to properly align the stock before beginning the cut.

A low-powered saw can bind allowing the blade to then grab the wood and sent it back at you.

A high saw blade cuts more vertically (thereby pushing the wood toward the table) than a low blade that cuts more horizontally and pushes the wood back toward the operator, but a high blade introduces other safety issues.

If in doubt, try ripping on a bandsaw.

[JPG]

Some other things that come to mind regarding kickback.

An improperly aligned saw--where the fence is closer to the blade in the back than in the front-- will pinch the wood.

A dull blade.

Warped, twisted, cupped boards, and trying to rip a board that doesn't have a straight edge can introduce binding along the way.

Small saw tables and fences are problematic because there is limited room in front of the blade to properly align the stock before beginning the cut.

A low-powered saw can bind allowing the blade to then grab the wood and sent it back at you.

A high saw blade cuts more vertically (thereby pushing the wood toward the table) than a low blade that cuts more horizontally and pushes the wood back toward the operator, but a high blade introduces other safety issues.

If in doubt, try ripping on a bandsaw.

Or a jig/scroll saw!:D SS say they will cut 2x? stock!

[baysidebob]

I agree that featherboards, push sticks. blade guards, splitters, riving knives are all good practice they are all something that are in our way until we get ourselves use to using them.

My mind drifts back to when I was 17 years old and just out of High School. Got a summer job working in an Lath and Grape Stakes Mill. Had been there about 2 weeks and the boss put me running a moulder saw. This saw had 8 or 10 blades on it and was used to cut fence lath. Going good until this nasty saw decided it was break time, or whatever. Anyway it shot back at me about 5 or 6 pieces at warp speed. Well like Dusty said S--- happens and it happens real quick. Pieces went thru my shirt and jacket pinning me to the unit of wood I was working from.

That experience taught me a lot of respect for any kind of table saw or sawing equipment. Not to say I have never done this again, but never to that extreme. I still have all extensions of myself and hope to remain this way.

MY worst accident came from working with a 1/2" wood chiesel. Looked away from project at hand and sliced right between thumb and index finger.

Didn't mean to get so windy with this, just happened.....At first I said I was 17 when working with the saw, well now I am 67 and still working with both power and hand tools, and still love doing it......

[Ed in Tampa]

Ed: The 'secret' to farmers holding firmly, is that by doing so, the workpiece doesn't 'start going south'. Add to that the fact that he knows when the workpiece will not cooperate. Back to the 'pay attention to what yer doin!'.

I have the opposite 'problem'. I tend to be too gentle when handling things and they tend to 'get away'. When a problem is anticipated, I will clamp down.

JPG
Interestingly I actually caused a problem with TOO much pressure. I was using the molding head and I was really pressing down on the table. What I accomplished was to push the table down increasing the bit of the moulding head cutter. Actually bent a moulding knife and chucked the wood a fair distance.
I now use a depth collar on the main table and rarely the moulding head cutter.

Perhaps I'm careless, stupid or something but I manage to find just about every mistake, or way to cause a problem. Needless to say I'm quickly learning to do things alternate ways than using the tablesaw for anything other than cutting and even then I'm cutting back on that.
Perhaps I'm an antithesis but I'm using more and more hand tools, hand power tools and my Radial Arm Saw. Yikes! I know but I like the idea that a Radial Arm the wood is fixed, my hand is controling the blade and my other hand is well away from the saw. Any kickback either moves the blade forward which triggers my thumb that is on the kill switch or shoots the wood away from me.

I don't do ripping on the Radial and I'm quickly getting talked into doing all my ripping on the band saw. Which makes sense since kerf is so thin you really save wood. I'm about this |<>| far from investing more in a guided saw system and doing 90% of all my cutting on it.