Table Saw Injury

[webgeek]

I'm typing this a bit slower than normal due to a table saw injury I sustained a week ago today.

I was cutting a small piece of plywood for my mill enclosure when the wood kicked back and slammed into the tip of my left-hand ring finger. I had all the guards in place - including the fence and the anti-kickback teeth attached to the blade guard and it still happened. I was even standing out of the path of the blade, wearing safety glasses AND using push sticks. The kick back was hard enough to break one of the the push sticks.

In the end, I suffered a commuted distal phalanx tuft fracture - a badly broken finger tip in English. It will take about 6 weeks to heal and with luck I won't lose any motion or have lingering pain issues.

My point? Even when you ARE being safe, you can still get hurt. The only thing I can think of that I did wrong was the piece of plywood might have been too small. Not sure on this but it's the only thing I can think of. Maybe this will inspire someone to be even safer than I was and avoid a relatively minor but very painful injury.

Mike

[wildwestpat]

Hi Mike

Sorry to hear you got hurt. This is a common source of difficulty with table saws. You need to have a riving knife that is the correct thickness for the saw blade in use. This stops the kerf closing on the blade and kicking back. With thin stuff the blade teeth should be set so that several are engaged with the material being cut either by lowering the blade or by changing to one with more teeth.

Speedy recovery

Pat

[webgeek]

I always set the blade so that it just pierces the top of whatever I'm cutting. I was told this was the "right way" to do it - is that the case?

The blade on it now is an "all purpose" blade, don't recall the tooth count. It's not super fine, I do know that.

As for the riving knife, the blade guard has an integrated one but after looking at pictures of them online (like this one: http://quietboating.com/images/PM2000_splitter.JPG) , I see that there are far better ones available that come much closer to the back of the blade. Thanks for the tip on that, I'll get one before I use it again.

- Mike

[wildwestpat]

Hi Mike

Yes it is good practice not to have too much of the blade above the table, It is also best if not imperative to have several teeth engaged with the material for the main length of the cut. This stops the job falling in to the gullet between the teeth. So for thin material a large number of teeth per inch are required.

Yes the support for the top guard is a sort of riving knife. In an ideal world the riving knife is matched to the kerf cut by the saw. This stops the blade being pinched by the material and is very often the case when ripping long boards which can kick back like a very bad tempered mule. The wood can twist as the tensions in the board are released with the cutting action. Yes the riving knife should be a close to the blade as practical. More often than not the sort of kick you have experienced will be due to the blade picking up on some feather or knot in the ply that you were cutting as well as the riving knife probably being too thin. The shape of the riving knife should match the blade diameter plus say 1/8 inch clearance to 1/4 inch gap.

Can I suggest you look at the types of circular saw blade that are available for your machine. The better makes of saw blade state quite clearly what they are intended to cut. For example ply will be a medium to fine TPI blade with probably three types of teeth - right cut - both sides - then left cut in rotation ans the blade goes round.. Even if you have to restrict yourself to the cheaper blades investing in those needed for the individual materials you want to cut is a good step towards safer cutting. However pick blades that have the same kerf and match the thickness of your riving knife. The blades should all be the same diameter or you will have to adjust the knife for every blade change.

Also the material can grab the blade if the riving knife and blade are not in line and both parallel to the fence. If you want to cut on the bias for a taper use a fixed support cut to the required taper and feed this through the saw parralel with the fence. You can also use a small block with a fence extension that is long enough to accomodate the work. Most accidents are due to a slip of attention and in my experience are most often when just cutting a bit to size rather than using a hand saw but it sounds as if you are well on the way to being a safe operator.

Hope I have answered the questions.

Regards

Pat

[ger21]

How small a piece were you cutting? Is the saw properly aligned? The blade should be perfectly aligned to the miter slot, and the fence should be parallel to the slot, or slightly (very slightly) open in the back. Does the back of the blade rub your part when cutting? It shouldn't. One thing that I always do is to make sure the part I'm cutting stays against the fence. I watch the fence when I cut, not the blade. (Make sure no body parts are in line with the blade).

I like to raise the blade a bit higher than the material, about 2" for 3/4" material.

[MadMax]

Rule of thumb I was taught in shop class was min 3 teeth should protrude thru the material with circular saws. Cutting tangentially with minimal tooth penetration gives you very efficient kickback (straight back push) when it happens and very little tendency for the blade to pull the mat'l against the table because the cut is primarily pushing back instead of against the table. Too much blade protrusion causes tearout (crappy surface finish on the bottom side) and exposes more blade than necessary.

Were you by chance cutting with the fence and a sliding square? Using a sliding square and a fence is a very good way to cause a nasty kickback. I think what happens is that a sliding square can cause the cut slot to pinch the blade. A properly set up riving knife stops this. You can also cause blade pinch by pushing horizontally too far from the blade. Advancing the material from the far end from the blade can cause the material to pinch a fair bit. I try to push between where the blade and end of the material sits when using a push stick with another stick pushing between the blade and the fence making sure that the mat'l stays firmly against the fence.

So far so good. I haven't had any nasty kickback yet and I hope I never do. I've sawn sheets of aluminum on a table saw. Scary stuff because the kickback can fling back a sharp edged sheet. I tend to make sure I'm wearing a good leather apron and gloves when sawing aluminum. I also make sure that the fence is very parallel to the blade.

[ViperTX]

While I live the riving knife...it not practical for pieces that 3/4 inch or less in width because it forces you to use push sticks.....which I think are quite dangerous.

What I use is a foot long 2x4 that has a handle cut in to it that way you never loose contact with the wood. The blade cuts into the 2x4 and after a while I have to replace it with another. Also when ripping wood that may have a tendency to pinch the wood against the blade....I use some tiny wedges that I use to hold the kerf open after I have fed 4 inches or so past the blade.

Paul

[wildwestpat]

Hi Mike

Suggest you check that the fence is parallel with the blade. Your description of having to use wedges to keep the kerf open suggests the fence is not lined up with the blade correctly.

Other wise you have a complete set of golden guide rules from everyone.

Wish you a speedy recovery.

Pat

[ViperTX]

Actually, I generally use the wedges as needed. Occassionally I'll be cutting a piece of hardwood and I can see the kerf start to close, not sure if the wood was not properly dried or if the internal stresses were built in as the tree was growing.

I'm very carefully with the fence being properly aligned to the blade.

Paul