sprior

Tony,

Thanks for your input. I thought that standing off to the side was a safety measure, user woodnthings even signs every post with "Never stand directly in front of a horse or tablesaw that's running!" So while I can understand the physics issue, is cutting plywood a case where standing in front of the saw can't be avoided?

Steve

woodnthings

There is a thread "kickback" and it explains why plywood and other manufactured sheet goods don't tend to kick back, generally. The exceptions to the rule are when the end pulls away from the fence to the left, binds the blade and everything rotates CCW into your belly button. The "don't stand directly" rule is more for ripping hardwoods and for more narrow stock and for those who don't know anything about horses! Any wood with "grain" has fibers that run parallel and some that cross over and may be in tension. When the tension is relieved by the saw cut, the wood may close up behind the blade, bind momentarily, and send it directly forward into your belly button, or worse, lower.
The purpose of the splitter or riving knife is to prevent to wood from closing back upon itself causing the kickback. Under-powered saws will bog down in the cut and bind up and do the same. Keep a clean blade free from pitch and that will also lessen kickback. JMO's
Another thread is:Kickback revisited
bill

__________________
Never stand directly in front of a horse or tablesaw that's running!
If you're not making dust, you're gathering it. After I reread my own posts, I agree with myself even more.

woodnthings

Kickback, lessons learned
Most of you already know that a structured wood like plywood or MDF or other manufactured sheet goods "generally speaking" will not close up behind the blade, the cause of most kickbacks, because they are stable. Other "natural woods, like pine and oaks MAY close up the kerf behind the blade and pinch and kick back. Therefore, use a splitter or riving knife which ever works or fits when ripping lumber off trees and when sawing sheet goods it's not "necessary". Don't get me wrong I've had plywood kick back from operator error, but not from the above condition. I was looking at my "welders leather apron" the other day and thought what a great shop apron for table saw duty, especially ripping. It would provide more protection than cotton or poly, IF a kickback should occur. Ballistic nylon would be best, but the best policy is never stand directly behind a horse or a table saw when either is running!
I have NO spiltter on by sheet goods saw, a Craftsman 12" motorized, but I DO have a splitter on my 12", 5 HP Powermatic used for ripping exclusively. My first cut on that saw when it was new OOTB, was ripping a scrap of pine from a crate. (no splitter, right, you know how to rip. right?) The wood EXPLODED after it pinched the back side of the blade and shot all the way across the shop! No blood no tears, just a whole lot more RESPECT! I also use a zero clearance throat plate at all times. It helps resist the temptation to go down into the throat plate after a thin sliver gets stuck, while the blade is still spinning. I had a kickback a few days ago, and it actually loosened the blade off the arbor, so I jambed a scrap into in after I had turned the saw off.. WOW! That was scary. Kickback occured when ripping a narrow piece against the fence wasn't pushed completely thru and pushed down as it exited the blade...overarm dust collector in the way! No Blood, no tears, just a lesson learned. Move the collector out of the way, and a pressure hold down roller behind the blade might have helped. That's why I'm am passing on this rather wordy response. Bad advice is plentiful, Good advice...priceless. Off for now, Bill

__________________
Never stand directly in front of a horse or tablesaw that's running!
If you're not making dust, you're gathering it. After I reread my own posts, I agree with myself even more.

cabinetman

The 'where to stand' issue is not a cut and dry issue. For those that have spent a lot of time using table saws it becomes apparent that what is being cut and its size will, more or less, dictate the best body position. The theory of 'not in a direct line' seems to make sense, but more importantly, if your body position makes the procedure uncomfortable or awkward, that in itself could present a more dangerous scenario, and put you at risk.

Minimizing the possibility of kickback can be done with just good operating procedure.

*Making sure the stock stays tight against the fence for the complete cut and pushed beyond the blade.

*Watching the stock edge along its path at the fence and NOT looking at the blade.

*Using a feed rate commensurate with the stock and blade, so as not to labor the cut.

*Using a smooth feed rate as possible when changing hands, or taking a step or two.

*Use featherboards and push sticks when applicable.

*Use eye and hearing protection.

*Moving/removing materials after the cut from behind the blade, or during the cut with the blade running is one of the common times table saw injuries occur. Placing your hand anywhere near or beyond the blade should be done with the saw turned 'OFF'. If that HAS to be done, extreme care has to be taken and paying attention to what you're doing is critical.

*I can't say this enough - paying attention to, and concentrating on what you're doing.

*If there is any doubt about the safety of the procedure, re-evaluate the issues before starting.

niki

Yes, but what is your answer to all those guys that clam " the blade guard is dangerous to use because I don't see how the blade is cutting the wood and I MUST see how the blade is cutting"...

Once, I replied "So maybe stick your head under the planer/thicknesser cutting blade because if you'll not see how the cutter is cutting - it's dangerous" (no, there was no reply to it)....

IMO, there are 2 kinds of Kickback;
A "Push back kickback - i.e. the workpiece is pushed back directly...in this case standing directly behind the work piece may cause an injury.

An "Over the Top" kickback that the workpiece is lifted up on top of the blade teeth, turned counter-clockwise and propelled back from the left side of the blade....So standing on the left of the blade, is like standing in front of the Tank shell....as you can see it here
http://www.metacafe.com/watch/910584...demonstration/


And here
note where the operator is standing - and he knows why.....

More info about kickback you can see here
http://www.waterfront-woods.com/Arti...w/tablesaw.htm

To minimize the kickback risk;
1. Use a splitter or riving knife.

2. Use a feather board (as possible - with very large sheets it might be impossible).

3. Use a "hold down" device like this one http://www.rockler.com/product.cfm?p...2&cookietest=1

4. IMO, using the blade guard, will dampen the severity of the kickback or even prevent it by not letting the workpiece to climb on top of the blade.

5.IMO, using a "low fence" can minimize the risk of kickback...When I'm saying "Low fence" I mean, a rip fence that is 1/2" or so high above the table....lets say the truth - what for you need a 3" high rip fence when you are ripping 1/2" or 3/4" or even 2" thick boards (I use the "High fence" only for Resawing)...

Please have a look at the 2 pics below to see what I mean "Low fence" and "High fence".

There is another thing to minimize the kickback risk but, I will not mention it because Cabinetman will "get on me" :)

Regards
niki

Tony B

Safety on the table saw includes being at a proper position to push a board through with a minimal amount of effort and a maximum amount of balance for both you and the wood. This does not matter whether it is a narrow board or a wide piece of plywood. If you are in an awkward position just to avoid being in line with the blade you will eventually get injured. You can not have full concentration on your cut if you are also worried about where you are standing. The combination of logic, comfort, balance , body mechanics and physics should determine where you stand. If you feel like making dry runs, set up your fence, lower the blade below the table top and push the board through as if you were making a cut. After a few trys, you will soon see what "feels" right and don't worry about where you are standing. To make this short 'do what comes natural'.
As for other safety issues, Cabinetman covered them pretty well.

__________________
Tony B

http://www.thetexaswoodworks.com