Tablesaw Kickback, the how and why..... - Woodworking Talk - Woodworkers Forum
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post #1 of 15 Old 08-06-2020, 10:20 AM Thread Starter
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Tablesaw Kickback, the how and why.....

Over the years I have had a few kickbacks on the tablesaw and I have learned why they happened and how to prevent them. I now keep my splitter on the older saws at all times and my riving knife on my newer saw. I have found excellent articles and videos on the prevention and explanation of what happens causing a kickback.


Starting here:
http://www.raygirling.com/kickback.htm


Under tablesaw techniques:
http://www.waterfront-woods.com/







That's about all you need to know to prevent them and be safe in the shop!
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Last edited by woodnthings; 08-06-2020 at 10:22 AM.
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post #2 of 15 Old 08-07-2020, 12:09 AM
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In school (Community College) the instructor does a demo during the first session of every class.

A piece of Styrofoam about 1 inch thick is used for a rip cut. The instructor deliberately twists the Styrofoam to cause a kick back. The effect is rather dramatic.

In one of my classes, a student dropped after seeing the demo. That was a shame as she had so much of an awareness for the why of safety that she would have done well in the class.

Rich
Just a dumb old paper boy from Brooklyn, NY
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post #3 of 15 Old 08-07-2020, 12:27 AM
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The current issue of Woodsmith magazine has a 4 page article titled, "Avoid Kickback." The article describes six different types of table saw kickback, their causes, and how to avoid them.

Woodsmith Magazine, Vol. 42 / No. 250, Aug/Sept 2020, pp. 62-65.
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post #4 of 15 Old 08-07-2020, 12:39 AM
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Those videos were so helpful and clear. Thanks for posting them.

Bill F.
post #5 of 15 Old 08-07-2020, 11:01 AM
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Many operations in the shop require no guard. Alot of blind drops on saws, etc.a lot of operations by professionals that a hobby woodworker should never perform...

With more shops incorporating CNC's in the shop, a lot of custom cutting is being dissolved on the tablesaw..

With the use of CNC's it's also clear the shop skills are diminishing as well..
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post #6 of 15 Old 08-07-2020, 12:23 PM Thread Starter
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Yeah, so what?

Quote:
Originally Posted by Rebelwork View Post
Many operations in the shop require no guard. Alot of blind drops on saws, etc.a lot of operations by professionals that a hobby woodworker should never perform...

With more shops incorporating CNC's in the shop, a lot of custom cutting is being dissolved on the tablesaw..

With the use of CNC's it's also clear the shop skills are diminishing as well..

How does this statement help prevent kickbacks? This thread is NOT about CNCs or necessarily "unsafe" operations performed by professionals in industrial settings. It's about tablesaw operations in typical workshops used by typical woodworkers. I don't really care what the pro's do with or without the safety guards.... I do care about my fellow woodworkers safety, however.



The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

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post #7 of 15 Old 08-07-2020, 01:33 PM
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There's more going on than basic saw operation in the shops...

It's the depth of skill that brings out my points. I forget there's only a few professionals on here...

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post #8 of 15 Old 08-07-2020, 01:36 PM Thread Starter
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Who cares?

Quote:
Originally Posted by Rebelwork View Post
There's more going on than basic saw operation in the shops...

We here are not industrial or commercial shops. We are typical woodworkers operating in home shops. If you are a pro then you would already know how to avoid kickbacks. The inexperienced folks here will NOT.


Stop hijacking my thread.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #9 of 15 Old 08-07-2020, 02:37 PM
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Good videos. I loved Kelly's gripe about the guard-less culture that seems to exist. He didn't say it explicitly, but one of his key points seemed to be that bad habits cause accidents. Just like sending a text while driving. As we say in poker, that works every time but once.

There's nothing wrong, it just doesn't work.
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post #10 of 15 Old 08-07-2020, 06:09 PM
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Quote:
Originally Posted by Lakewood Brian View Post
Good videos. I loved Kelly's gripe about the guard-less culture that seems to exist. He didn't say it explicitly, but one of his key points seemed to be that bad habits cause accidents. Just like sending a text while driving. As we say in poker, that works every time but once.
I saw that same gripe, and it made me wonder what would happen if the demos and TV shows were filmed with the guards and splitters attached? Would it really affect how much we see an learn? I doubt it.
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post #11 of 15 Old 08-08-2020, 05:26 AM
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Quote:
Originally Posted by Rebelwork View Post
I forget there's only a few professionals on here...
Well, you know how that goes, right? Do as I say, not as I do.

I've had this unlisted video for a decade, and it's unlisted for a darn good reason. I recorded it to show my friend (the one operating the camera) how I rip hundreds of board feet of stock for production of frame stock. (These were stretchers for her workbench we were building.) You can even hear her exclaim, "You're right, they're gonna hate that."

But as long as I'm showing it, I'm going to point out a couple of the details of how I do it.

  • Before I start the cut, only the leading corner of the board touches the fence. The rest is intentionally skewed away from the fence.
.
  • As soon as the wood is engaged with the blade, I straighten out parallel to the fence.
.
  • It's hard to see, but I'm bearing down so hard on the front of the board, and pulling up on the rear (like a pry bar), that I am flexing the board. This is to prevent the board from climbing up the blade, due to the forward down-force.
.
  • Related to that, I maintain absolute control over the board, to such an extent that there is no physical way for the saw to wrest control away from me. There is nothing delicate, dainty, or hesitant about the way I control the board. In a brute force between me and the motor, I win, because I never permit the blade to get a foothold.
.
  • I stand at the rear end of the board, no matter how long it is, so I do not have to change positions during the cut. Never feed in short choppy spurts.
.
  • My left hand is wearing a snug fitting leather glove to prevent splinters that could cause me to jerk away from the board. I have a whole bunch of right-hand gloves that are brand new, but all of the left-hand ones have the sides worn out of the index finger.
.
  • My right hand is gloveless, because I want the friction of skin on aluminum as my hand uses the fence for hand-control at the end of the cut. The top of the Unifence rides between my index and middle fingers, and there is no way my hand can move sideways toward the blade. (This is why I prefer a Unifence over a Biesemeyer fence.)
.
  • I don't normally cross the blade with the finished cut (the right-hand piece), but at the time, I was reorganizing the shop and the saw table was stacked with panels. Normally the finish cut goes to the right of the fence, and the offcut goes to the left for a re-cut.
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post #12 of 15 Old 08-08-2020, 09:21 AM
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The biggest reason I get kickbacks by far is by simply forgetting to move the fence far enough away when I'm cutting pieces off with the miter gauge. I get in a hurry and little chunks go flying..of course my saw often offers me money to look the other way..I never take it. I probably should. I could afford a better saw.

I figured it's time to change my signature so hold your breath. This is it.
Impressive, huh?
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post #13 of 15 Old 08-08-2020, 10:29 AM Thread Starter
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Other safety issues ......

Using the properly designed push stick/shoe is also important when making a rip cut. The slender "fish shaped" one that are the most commonly supplied with a new saw are also the worst design!
WHY?
There are three major forces that you need to apply to the workpiece when ripping, downward and forward and diagonally. The short horizontal step on the long, long, slender push sticks just ain't enough to apply downward or diagonal pressure. You need about 7" to 10" of horizontal foot to apply adequate force. This is where the "push shoe" is the better design. It allows good down pressure as well as forward and diagonal pressure.

The diagonal force is very important, especially when there is no splitter or riving knife on the saw. That diagonal force, is in towards the fence in order to keep the workpiece registered along the fence the entire length of the cut. Most kickbacks occur when the far end of the workpiece moves just slightly away and off the fence, rotates upward and over onto the spinning blade and shoots the workpiece back at you, the operator!


This video goes over some of the faults of the more common push stick and includes the reasons a push shoe is the best design:


This video is also a pretty good one:




The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

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post #14 of 15 Old 08-08-2020, 03:17 PM
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Quote:
Originally Posted by woodnthings View Post
The diagonal force is very important, especially when there is no splitter or riving knife on the saw. That diagonal force, is in towards the fence in order to keep the workpiece registered along the fence the entire length of the cut.
You should really re-evaluate your direction of force when using a push stick/shoe. Never use the stick/shoe to apply lateral/diagonal force toward the fence. Why? Because as you are applying force to the board toward the right, your hand is experiencing counter-force toward the left...toward the blade!

In other words, if something goes wrong and the shoe slips, your hand will already have the propensity to move to the left. (The shoe will rotate to the right, like slipping on a banana peel.)

If you need lateral force, that is where a featherboard comes into play.

For similar reasons, I never use a push stick when the cut is wide enough that the push shoe is not riding directly against the fence. When my push shoe is moving past the blade, 3 or 4 of my fingers are sliding along the right side of the Unifence. If you are using a Biesemeyer fence, then the best shoe is one that wraps the fence like your video showed.

A few years ago I was called as an expert witness for a tablesaw injury case in British Columbia. The case hinged on the over-use of push "sticks", and the oporator's right hand moved into the blade. The operator wasn't in control of the workpiece, his push sticks (2 of them) were in control. The diagonal forces permitted his hand to drop down onto the spinning blade. (I replicated his cut with a live blade for photo purposes, and I was terrified the entire time.)
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post #15 of 15 Old 08-10-2020, 08:36 AM Thread Starter
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I don't like the handles I see on push shoes ......

With some experience as a pistol shooter, the grip is most important. More specifically, how the wrists react to the upward recoil and prevent lateral movement. The typical handles is see don't prevent the wrist from twisting/rotating and in my opinion are not ideal or really safe. I prefer a grip on the push shoe that allows for a pointed fore finger. This allows much greater down pressure than a finger wrap around grip and that's the design I've come up with after years of experimenting with making them. There are simple shapes that make this leverage possible.

There are no images I've found that meet this requirement here:
https://www.google.com/search?q=tabl...w=1536&bih=722

If we play the "what if" scenario and the push shoe "slips" then it lacked the proper adhesion on the stock or the catch lip was not adequate, or the diagonal force was too great or ... other factors. If you are pushing on a left to right diagonal towards the fence, I don't understand how that would result in anything other than a slip from left to right. We are using a push stick for stock that's too narrow for a hand to pass safely between the fence and blade. Better to chew up the push stick than one's hands or fingers, in my opinion.
Since the main reason shown in the videos and in my own experience for kickbacks is the work coming away from the fence at the rear of the blade and rotating up and over, the application of diagonal force by what ever means, is certainly the best preventative. Many times I use the thumb locked over the left edge of the stock when the workpiece is of adequate width. I also utilize the splitters on my older saws, but I realize they are in the way for some stopped or limited depth cuts. Thats' why my newer saw has a riving knife that's easily removable, unlike the splitters.

I realize that not every one has the luxury of having more than one table saw, so some of my advice will not apply to everyone. However, the videos do demonstrate how the splitters and riving knives do assist in maintaining the workpiece against the rear of the fence. In my case, I can't remember that last time I used a feather board on my table saw even though one is within arm's reach under the saw. I have both the instant release magnet type and the type that fits in the miter slot, but they just don't get used much as I don't feel I "need" them.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)

Last edited by woodnthings; 08-10-2020 at 08:38 AM.
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