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kick back observations

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Forum topic by sixstringjack posted 1132 days ago 1316 views 0 times favorited 13 replies Add to Favorites Watch
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sixstringjack

9 posts in 1132 days


1132 days ago

modern table saws with riving knives have no anti- kickback pawls. Is this an indication that they are unnecessary? It seems to me that once the workpiece passes the leading edge of any splitter, the likelihood of kickback is nil. Since the pawls are located father back than the leading edge, are they superfluous? Query: has anyone actually experienced a kickback stopped by the pawls? In 490 years of woodworking i have had my share of kickbacks and never had the pawls stop any of them.

Secondly, most experts suggest that the operator stand to the left side of the blade when ripping, not directly behind the workpiece. However, utube clips of intentionally induced kickback show the piece coming off the saw at about a 40 degree angle, directly where the operator would be standing if he stood off to the left side. It seems the only really safe place would be , with the fence on the right side of the blade, to stand to the RIGHT of the fence and push with the left hand. This would be uncomfortable for right handed people. I would never try it myself. Any comments?

—Jack

-- Jack


13 replies so far

View Loren's profile

Loren

7389 posts in 2273 days


#1 posted 1132 days ago

A riving knife is wider than the splitter used to mount pawls on older
saws. The old splitters don’t do much to stop kickback on their own
because they tend to be too narrow – presumably they could have
been made wider but that would have added to manufacturing costs.

Pawls are essential when ripping with a RAS. I’ve used them and I think
they can work. Still, I prefer a real riving knife slightly narrower than and
immediately aft of the blade. A riving knife mostly prevents kickback
from pinching – but it does not prevent all possible forms of kickback.

I’ve experienced minor kickback a couple of times and had the piece
come straight back and hit me in the stomach.

-- http://lawoodworking.com

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rance

4128 posts in 1786 days


#2 posted 1132 days ago

I’m not a believer in using pawls. Like you pointed out, I’ve never seen then actually do what they were designed to do. If you have some that actually grip the wood coming back, then they always have marred the wood going forward too, thus messing up the finish surface of your wood.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

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David Grimes

2072 posts in 1265 days


#3 posted 1132 days ago

First: With a riving knife, fence parallel with the blade, magnetic featherboard properly in place, and (again) proper use of push stick and hands, I have seen no indication of kickback on my saw.

Second: I will stand wherever I need to so that I can accomplish all of the above.

I will not hide or peak around the corner on my tools. ;=)

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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rance

4128 posts in 1786 days


#4 posted 1132 days ago

>“I will not hide or peak around the corner on my tools. ;=)”

That’s a hoot, but I agree with everything you said, especially that last line.

I think the biggest problem folks have had with kickback is them not knowing when it can happen and what can cause it. 99% of the time I know what can cause it, and I provide extra attention to the task. Kickback should never be a surprise. If it is, then more education might be in order.

I usually don’t stand directly behind the blade in case a carbide tooth decides to l’eave the building’ but standing on the opposite side of the fence seems ludicrice to me.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

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David Grimes

2072 posts in 1265 days


#5 posted 1132 days ago

The sliding miter saw is the one I watch real close “hand-wise”.

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

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BorkBob

62 posts in 1318 days


#6 posted 1132 days ago

IMO, riving knives are far superior to splitters because they are much closer to the back of the blade. Preventing the offcut from contacting the back of the blade prevents that kind of kickback.

Kickbacks that result from the entire workpiece riding up on the blade may be prevented by the use of pawls, but proper technique and control of the workpiece will work, too.

I’m not a believer in the idea that splitters or riving knives are designed to prevent the work from closing on the blade. The splitter or RK is thinner than the saw kerf; if the kerf closes, the work will impinge the saw teeth before closing on the splitter/RK.

I also don’t think a splitter/RK should be counted on the hold the work against the fence. That’s what we’re there for.

Be safe.

-- Please Pray for Our Troops / Semper Fi / Bob Ross / www.theborkstore.com

View sixstringjack's profile

sixstringjack

9 posts in 1132 days


#7 posted 1131 days ago

Interesting view points, guys. Still i am curious, has anybody actually seen anti-kickback pawls work?

-- Jack

View David Grimes's profile

David Grimes

2072 posts in 1265 days


#8 posted 1131 days ago

Maybe just the fact that they are there and there is no kickback is a testament to their working. Let’s re-phrase the question: Has anybody experienced kickback with pawls properly installed ?

-- If you're going to stir the pot, think BIG spoon or SMALL boat paddle. David Grimes, Georgia

View Manitario's profile

Manitario

2298 posts in 1508 days


#9 posted 1131 days ago

Personally, I find pawls a pain-in-the….I’ve removed them of of the blade guards on all the TS I’ve owned. The only things I’ve found them good for are scratching soft wood, trapping thin strips against the blade and/or preventing me from withdrawing the board if I need to. David: I agree about the sliding MS; if I ever injure myself on a saw it will be the MS, it is way easier to have a moment of carelessness and let your finger slip under the blade than with the TS…

-- Sometimes the creative process requires foul language. -- Charles Neil

View Cosmicsniper's profile

Cosmicsniper

2199 posts in 1784 days


#10 posted 1131 days ago

Rob nailed it for me. Using the pawls, I don’t like that it traps thin strips at the blade…in fact this occurs with my blade guard as well, both with and without the pawls. The guard saves me the impact of the kickback, but I don’t like the fact that i can’t clear the board with that cut. So, for such cuts I remove the guard…and I find the pawls useless anyway…more often than not, I just go with the splitter.

I’ve come to the decision that the only useful guard is one that is suspended overhead, not one that attaches from the splitter, like my Sharkguard.

-- jay, www.allaboutastro.com

View MedicKen's profile

MedicKen

1599 posts in 2087 days


#11 posted 1131 days ago

I don’t like the pawls at all, nor do I like the idea of ripping on a radial arm saw. I think ripping on a RAS is asking for a disaster. My table saw has a riving knife, or at least the provision for one. My table saw is an Oliver built in 1953 and they did have true riving knives in the day. My bracket is missing and I will need to fabricate one and a knife as well. On all of the other table saws I have owned prior to my Oliver I completely removed the pawls, splitter and bracket in favor of a home made splitter.

-- My job is to give my kids things to discuss with their therapist....medic20447@gmail.com

View mcase's profile

mcase

438 posts in 1754 days


#12 posted 1131 days ago

490 year of wood working? I’ll defer to your experience Six! Seriously though, in over 49 years and plenty of kick backs you have never seen the pawls function and feel that once “workpiece passes the leading edge of any splitter, the likelihood of kickback is nil.” This is an interesting and important observation. In this case the kick backs must be occurring well before the work piece reaches the pawls as you point out. In fact it must be occurring before the workpiece even reaches the leading edge of the splitter. If this is the case it would seem that a riving knife which is thicker, sits tighter to the blade, and follows its curvature more closely than a splitter would have a better chance at preventing a kick back. It would be interesting to see an objective study that verified either the usefulness or uselessness of both systems.

View SnowyRiver's profile

SnowyRiver

51451 posts in 2105 days


#13 posted 1125 days ago

I have never seen pawls stop anything myself. I have them but never use them. I would think they would keep the board down on the table so it cant lift on top of the blade and wont let the board pull back. I always use the riving knife especially after a kick-back a couple of years ago that almost knocked me off my feet and caused swollen lympth glands in my lungs which the doctor found on an XRAY. Kick-back is most often caused by the leading edge of the board crossing over the rear of the blade. Once it does this the blade will pick up the board and fire it back at you like a frizbee. I suppose in this case a pawl might keep it down on the table, but if you have a riving knife you are pretty safe even if it’s a bit thinner than the blade. I use a thin kerf riving knife even with a standard blad. There still isnt enough of the blade exposed for it to grab the board.

When I was in school many years ago we had pawls on the 5 hp Delta table saws but we still had long boards that were being ripped kick straight back….one even went through a sheetrock wall in the instructors office :-)

-- Wayne - Plymouth MN

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