Potpourri - July, Aug, Sept 2010

[swampgator]

Today, I received my first copy of Hands On from Jan/Feb 1984, about the same date as my first SS Mk 5. Some neat stuff but makes you realize that it was the days before the internet. Some things I had seen advertised on SS website and in their emails had descriptions and purposes in this magazine. Found it on eBay last week. Originaly sold for $1 and I paid $5.95 but well worth it to me. Some good stuff.

[mickyd]

In my shop all rip cuts are with the fence to the right of the blade.

Multiple 'shorter identical size cross cuts are done with the fence left of the blade. Of course using a spacing block attached to the fence.

Anything technically wrong with fence on the left? I'm finding that's my preference, pushstick feeding with my right hand, body/head to the left of the fence (anticipating the kickback I've heard so much about yet have yet to experienced ).

[Stitch]

Anything technically wrong with fence on the left? I'm finding that's my preference, pushstick feeding with my right hand, body/head to the left of the fence (anticipating the kickback I've heard so much about yet have yet to experienced ).

I hope you don't ever have the experience of a kickback. I just caught one in the chest a few days ago and I am still black and blue. I am just thankful that it did not catch me in the face or hands. I wish I knew exactly what I did to cause it.

[burkhome]

In 81 shortly after procuring my glorious Mark V, I was set up in an 8 x 9 bedroom. I did something stupid with a thin piece of oak and put it through the drywall. It stuck out in the kitchen. My wife suddenly wasn't very impressed with me or the shopsmith... Always stand to one side and make sure noone is standing behind you.

[JPG]

One stubborn member's opinion!

Kickback is(as I understand it) caused by the workpiece getting pinched between the rotating blade and the fence(or some other relatively immovable object). This pinching condition if allowed to 'pinch harder'(caused by the blade deflecting and the workpiece becoming further wedged) will eventually result in the pinch being relieved by the launching of the workpiece into flight at a very high velocity.

Prevention of this phenomenon requires avoiding getting the workpiece wedged between the fence and the blade.

Now I would agree that if it is likely to occur, that positioning oneself out of the potential path would be a prudent thing to do, however, IMHO it is far more prudent to prevent the condition for kickback in the first place.

I always exert a force on the workpiece in addition to causing forward motion of the workpiece, an additional push both towards the fence(in front of the blade) and a torque that tends to twist the workpiece against the fence behind the blade. Now this is all well and good with well behaved workpieces, but warpage/internal stresses can require direct pressure against the fence behind the blade.

Now I do not mind reaching over the blade to exert that force behind the blade, but I do not relish doing so to apply the force(s) in front of the blade.


Thus I typically position the fence to the right of the blade, push the workpiece with my right hand, and when required, pushing the workpiece with my left hand behind the blade. All this assumes the left hand is not needed for a different purpose.

If due to warpage etc. I recognize a tendency of the workpiece to move towards the back of the blade, I will try to position myself further to the left than typical(trying to be to the left of any potential flight path). This also requires pushing the workpiece from a higher angle(arms higher so any flying objects will pass under them).

Now for the 'kicker! I have never used either a blade guard(upper or lower) or a riving knife. I have FULL visibility of what is happening at the rear of the blade as it rises above the workpiece. I attribute(somewhat) that ability to 'see' what is about to happen as a reason I have not thrown workpieces toward a wall let alone through one.

Now on those rare occasions when I use the fence to the left of the blade, the description above is followed, but with left/right being reversed.

In any event, paying attention is the crucial ingredient. Larger workpieces are not likely to be involved in kickback, but when approaching the end of a cut, the potential increases. It is also the point at which we do not want our hands near the rotating skin ripper so we tend to ease off the pressure. Unfortunately it is also the point in time when one's mind tends to wander to the next thing to be done. Best to wait until the current activity is completed!!!

Oh! Also important is to make sure the workpiece does not rise above the table(usually tends to near the end of a cut also)!!!

Ok! Next opinion!

[shipwright]

OK JPEG since you asked, if anyone hasn't heard my opinion on kickback already, here goes, one more time.

Shipwright's kickback rant: (again)

1) Twisted or warped pieces don't go in the table saw. That's why god gave us jointers and hand planes.

2) Tension caused by internal stresses in the wood won't ambush you. It will build up slowly and if you're paying attention you'll stop and poke a little wedge in the kerf before it goes critical.

3) Push sticks CAUSE kickbacks, they don't prevent them. A "shoe" gives you the control required to prevent kickback.

4) IMHO, standing BEHIND the cut is where you are able to exercise the greatest control over your piece and since kickback only occurs when you lose control of your piece, it seems only logical to me that the place to be is behind the cut not having kickbacks instead of beside the cut thanking your lucky stars that the barrage of projectiles emanating from your saw are missing you. If you don't understand how to control your piece, you probably shouldn't be using a table saw.

5) Know your machine, a little basic physics, and pay attention.

6) You can't be tentative. Table saws are like dogs and horses. They can sense fear and they will act accordingly.

7) Before someone asks, I don't know how it is that you are supposed to gain this knowledge and confidence but I know that with it kickbacks just don't happen and without it, apparently they do.

OK, I'm done now.

Blame JPEG, he asked

Paul M

[Stitch]

This is a very interesting discussion. At least it is to me. Obviously, a long discussion will likely result in many opinions coming forth.

In the case of this kickback that I just experienced, a push stick was not to blame. There was no push device other than my hands being used.

[horologist]

In any event, paying attention is the crucial ingredient.

I agree this is the crucial point and you make a bunch of other good points.

I'm not going to get caught up in the guard/no guard argument. Personally, for the most part, I use them. While I can understand and even agree with some of the points raised by the no guard fans, it isn't how I was raised and to go guard free just seems wrong. Sort of like starting a car with an automatic transmission after a lifetime of driving manual. Turning that key without pushing in a clutch just feels wrong! YMMV

Not necessarily a kickback preventative...
One other addition, while you are pushing the workpiece to guide it through the blade, consider the direction of thrust and where your hands will go if whatever you are pushing were to suddenly vanish. This applies to other tools including hand tools such as carving chisels.

Troy

[robinson46176]

Several very good responses here. I would only add a couple of things.
One: This one relates to Shipwright's #6. I feel that a lot of woodworkers get in trouble when a cut is going smoothly and they start to relax... Not me... While I have a great deal of confidence in all kinds of shop work I maintain a Godzilla grip on things from start to finish. I want that SOB to hug that table. I hate seeing "Norm" making cuts and I can see the out feed end of the board lifting up maybe even a half inch. I do not intend for that to happen on my watch. NEVER use a light touch. Be in control. I am fond of using feather boards when ripping.
Two: Relates to Shipwright's #1. I think a whole lot of woodworkers are always heading for the table saw when they just shouldn't. hand tools many times and a number of other options like a bandsaw, jigsaw or even a scrollsaw might be better. I see a lot of talk about cutting very small pieces on the tablesaw. No one in their right mind would need to cut a piece off of a 4" long piece of 1" x 4" stock and grab their hand-held Skillsaw to cut it with (would they?). So why would you think that flipping saw upside down, tripling the horsepower on the motor and nearly doubling the blade size makes such a cut make sense??? Would you use your RAS to cut a 2" long piece of 2" x 2" in half?
If your scrap from a rip cut is so short that it is likely to fall down in the blade slot maybe you don't need a ZCI, maybe you need to be using a different tool...

[burkhome]

I too don't use guards. I haven't thrown a piece in some 25 years because I gained a little experience in set up and care. I use feather boards a lot. I have learned how high the blade should be. I have learned that you are asking for trouble using a dull blade. I have learned when I can reach around the blade and when I can't. (my dad lost a couple of fingers reaching around the blade and getting pulled back into the blade...of course he was in a hurry). I don't get in a hurry if I am in the shop. If I get to where I want to hurry, I put the tools away and stop... This has improved my results exponentially. I still stand to one side as I feed things through the saw. Not plywood or large pieces.