Does the size of the motor have much influence on kickback? I am somewhat surprised at the number of people who have experienced kickback. I have been a hobbyist for over 20 years using a Jet contractor saw and luckily so far I have not had any real issues with violent kickbacks. Am I in for something new when I upgrade to a cabinet saw?
Charlie
Replies
charliez,
If you always use your safety guard the cabinet saw is just as safe as the contractors saw. I broke my wrist when I removed mine and used a too coarse a tooth blade. You wouldn't think a piece of wood that small could shatter a wrist bone. It was about 3/8ths of an inch thick two inches wide and maybe 4 inches long.
My wrist would have been just as shattered with the contractors saw I used to use.
Upgrading to a cabinet saw should decrease the frequency of kickbacks. There is a lot of misinformation on this because a lot of people don’t understand the differences between the various types of kickback, and therefore, just lump them all together.
For any of the binding or impact type kickbacks, the larger the saw motor, the less likely the kickback will occur. This is because the motor will not bog down to the point of being able to grab the wood. As long as there is a high differential in sped between the blade teeth and the workpiece, it won’t kickback (unless the operator panics and lets go!!!)
However, once the kickback does begin to occur, the torque of the motor will propel the workpiece with more force. However, this is a moot point for small pieces, where any motor will deliver about the same force to the workpiece.
For rotational or over-the-top types of kickback, the size of the motor has little impact because the speed of the blade is not brought down to a bogging level during the course of the kickback. The frequency and power of the kickback will be the same for nearly all saws (with exception to the really small saws).
Nicely said Rick. I agree all of the way.
The size of the motor has a lot to do with kickback. Unless you are doing a lot of cutting in 2 inch and thicker hardwood, you don't need more than a 2 HP motor and a sharp blade. Too many people think they have to have a large motor and the bigger the better. Not so. It is more important to keep your saw equipped with a sharp, well maintained blade. If you have to use more than the lightest pressure to push wood through your saw, your blade is dull and there is nothing worse than a dull blade on a circular saw.
Hmm. Lots of posts say a larger motor won't increase the liklihood of kickbacks, or even reduce them. Let's just say I'm skeptical. I have a contractor's saw with only a 1-1/2 hp motor. (I was pretty much a hand tool user until I needed to make a bunch of cabinetry fast, so I purchased the saw.) My saw will bog down, and even groan to a stop part way into a rip when it encounters reaction wood that results in a blade pinch. No real danger of a kickback, since I'm apparently stonger than the saw motor! I suspect that a 5 hp cab saw wouldn't be so forgiving. If I were to upgrade to a more powerful saw, I'd be a LOT more careful in this regard, and would be sure to use a real splitter (mine's just sheet steel, way thinner than the kerf) or a riving knife. And, I'm sure I would use the guard religiously. (I'm one of those who has gotten into the habit of leaving it off more than I should.)
Mike Hennessy
Pittsburgh, PA
In your case, if the wood pinches then the saw won't drop RPMs, just push it on through and clean up the burn area. Always keep strong downward presure hold on the piece. A splitter sounds like a great idea, and I bet it would be somewhat safer, I just don't have one yet. As long as rps are up and piece is being held down wood shouldn't grap. Just don't drop anything back onto a blade or you'll see a missile launched. I feel safer with the cabinet saw knowing that it won't let me down in the middle of a rip by grinding to a hault and doing who knows what.
Nathan
Mike,The worst kickback incident I ever experienced was when moving from an OLD sears 1HP table saw to my Unisaw. My experience was exactly as you surmise, on the old saw, if the blade began to bind then the motor would stall or the belt would slip. Not so on the Unisaw.I had just gotten it set up, and was using it for the first time. The ONLY piece of lumber I had to cut was a warped piece of 1/4 plywood. It bound up, sheared past the splitter, took out the blade guard and came back at me...leaving a nice bruise on my stomach.Lessons learned, in no particular order:1. 3HP, is a lot, with a triple belt drive...wow...watch out.
2. More important than any piece of safety gear is common sense about what you are cutting, how you are cutting and why you are cutting. Use good materials, use good judgement and don't rush to operate.Scott
All these kickback horror stories are making me nervous...
What we need is commercially available body armor for woodworking...maybe a nice kevlar shop apron or something. Now, don't anyone steal my idea before I get it into production... Where's that telephone book...
Best wishes.
Rick
Been done. See, for instance, http://forums.taunton.com/n/main.asp?webtag=fw-knots&msg=33808
LOML gave me a Lie-Nielsen leather apron as a gift several years back. Weighs in at about 2.4 pounds. Several small chunks have bounced off it. I suspect that they might have hurt at least a little bit. I consider the apron part of my cutting garb: safety glasses, ear plugs, apron, two shots of tequila for courage. (I'm kidding about the courage--I respect the blade no matter how many shots I have.)
Reminds me of a case back in the early 60's. I was a young shop teacher in a small school in northern Indiana. The shop was small and equipped with Sears tools. A student decided to rip a narrow piece on the radial saw,(not a wise thing), when it kicked and hit him in the stomach. As luck would have it, he was wearing a wide, heavy leather belt. The wood made a direct hit on the belt and he was not injured. Kevlar apron???? Maybe you have something here.
I agree with the leather apron. I had a small piece of wood 3/8" wide by 3/16" thick x 3" long spear me below the belt .A trip to Er and 12 stitches to remove it ,. I was ripping oak flooring with a stock feeder.the small piece was the off cut.I was always a little over confident using the stock feeder as i felt protected from the blade.Not really concerned about the off cut as i knew that it would be small.but as i found out ,painfull. Leather apron is a good idea .
As far as HP i'am more is better.Of course a sharp blade is #1. I'am not a big fan of thin kerf blades although i know they help out a lot on under powered saws.More hp and i don't have to use TKB 's.or blade stabilizers and of course make allowance on my fence tape. More hp .keeps the rpm up alowing the blade to run cooler and as i'am sure you all know, the binding, burning and white knuckles trying to get er done. IMHO 2 hp would be minimum that i would want to operate. my .02 cents Chris
Rick: Now that's a great idea! Ceramic plates under my leather apron or kevlar. Does it have to have D.O.J. approval like a standard b.p. vest? "This apron good for 20 inchs of 2x4 or 9mm" :)
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Like with anything else dealing with woodworking, I'm sure there is more than one answer to the OP's question. For me, though, the only reason I'd ever switch to a more powerful saw is to get a Sawstop. Not to start that argument again but, although I have no need for additional power (heck, I spent years dealing with a 1 manpower saw <g>) and my saw is plenty accurate for general woodworking, it would be nice to have the added protection of the Sawstop safety system (including the riving knife). I've never had an accident with the TS other than a couple of KB's that I was "prepared" for, but every once in a while, I'll start the saw, position the wood to start a cut, and find myself looking at the spinning blade and wondering if I've lost my mind to be doing this. <G>
Mike HennessyPittsburgh, PA
Mr. H, am I understanding correctly, the SawStop will not prevent kickbacks any better or worse than any other saw, will it?
Because the Sawstop has a true riving knife, it will no doubt prevent kickback a lot better than my saw (or most other US saws), which only has a sheet metal splitter that pretty much does NOTHING since it's so much narrower than the saw kerf. And even if it didn't, the "hotdog protector' feature is the main thing that makes me think of upgrading my cheapo, but good enough for my purposes, contractor's saw. When they come out with their new contractor's model, I'll probably be the first in line. Even though I'll probably never need to use the "hotdog protector" feature. (I don't expect I'll ever use the airbags in my car either -- but I still got 'em.)
Mike HennessyPittsburgh, PA
The chance of a kickback is, or should be, higher than a body part coming into contact with the blade. One thing more people should do is mark the saw table with a line that lets them know where the blade is when it's covered by the wood, IMO. That way, they don't have to be able to triangulate the blade's location if they're standing to the side. Mine is marked all the way to the blade and when it becomes hard to see, I mark it again. Since I clean the top annually, it gets marked annually. This year, the splitter will be much stronger (I'm making a new one out of a piece of 1/8" steel).
"I cut this piece four times and it's still too short."
Kick back occurs when the wood lifts off the table, which is usually caused by the wood pressing against the back part of the blade, and the wood getting against the side or on top of the saw teeth at the highest area of the blade where the forward moving teeth shoot it towards the operator.
A riving knife, such as the one on a Saw Stop, compared to a splitter, does a much better job at keeping the wood away from back and top areas the blade making the most forceful kick backs much less likely to happen.
John White, Shop Manager, Fine Woodworking Magazine
My General has a knife that like on it, but it seems pretty flimsy. Thanks for the explanation.
Are those plastic poke in splitters any good or are they worthless in your opinion?
The splitter on your General, while it looks the same as a riving knife, doesn't work the same, since it stays fixed when the blade height is changed allowing a large gap between the teeth on the blade and the splitter when the blade height is set below full height. A riving knife rises and falls with the blade, always giving the maximum amount of protection no matter what the blade height.
How can I say this diplomatically?, the little plastic things are better than nothing I suppose.
John W.
I wondered about those little plastic things as well. I decided against them, the main reason is I don't know how well they would work on a piece of wood the closed up on it. I can just imagine the plastic thing getting pulled out, and levering the wood upwards... I'm sure for 99% of cuts it would be alright.
As well they don't tilt, so I'd be splitterless if I had to make a bevel cut.
Edited 4/18/2007 6:36 pm by Buster2000
little plastic things............
I've wondered the same myself. But as the host said, they're probably better than nothing at all.
True. Something is better than nothing... I was just being less diplomatic than our host.
As well I was just seeing if anybody else had this problem or, was thinking along the same lines.
OK -- I will show my ignorance but it seems that when I have long boards to rip or any kind of twist in the board I have been using my bandsaw with outfeed support. Feel very safe and the cut is accurate and, yes, the cut is not as 'clean' as my table saw but my Jet contractors saw with a thin kerf frued rip blade and the stock splitter/guard is almost unusable on some boards. I was cutting 6' 4/4 ash and finnaly gave up trying to get a cut past my stock splitter and used the band saw.
Am I wrong here?
Scott
Scott,
You aren't wrong at all.
Though not without its risks, a bandsaw is almost always the better choice for ripping especially if the wood is gnarly and likely to move. Using a band saw for ripping, since it is safer, should be mentioned more often when discussions about table saw kickback come up.
John White, Shop Manager, Fine Woodworking Magazine
No, your not wrong. The band saw is one of the safer tools you can have in the shop. There is always the debate about what tool to buy first, and almost always it is a table saw that most people recommend. But I, and a few others, think the bandsaw first. The band saw can't kick back, so if you want to trim wood that the grain screams at you is going to react, or the first piece of the ten you need to cut from wood from the same source did, you can always use the band saw.
With a bandsaw you can rip if you want to, but it does curves that the table saw can't. In reality it comes down to whether you make cabinets, or furniture such as chairs, that have more curved surfaces than straight ones.
Let me add one thing to this debate. That is that your saw must be properly aligned to minimize the chance of a kick back. In the tablesaw safety course I used to teach, I stressed, saw alignment, blade sharpness and appropriate blade for the operation as the basic issue with safety. I do not believe that motor power has a significant impact on kickback. If your saw is having problems ripping thicker stock, be sure you are using the correct blade. In addition, if you are dealing with reaction wood, the number one--by far--safety item is a proper splitter or riving knife. More power is not the answer. Tablesaws expect the blade pressure to be at the front of the blade where the directtion of force is downward toward the table. If the kerf starts pinching together, the force is now at the back of the blade where the blade rotation causing the force to be upward away from the table. This lifts the back of the board and results in kickback. A properly aligned and sized spitter will prevent the pinching to close the kerf around the back of the blade.Howie.........
have you solved your problem, regarding kickbacks?
would like to hear from you, iff you have not solved it.
regards nottingham
Since I am upgrading from a contractor saw to a cabinet saw I was just wondering if I should expect anything different with regards to kickback since I really never had any problems with kickback in the past. In short yes my question has been answered. Thanks to all who replied.
Charlie
I did the same thing-
Upgraded from a saw I could stall out when the need arised to a Unisaw. Like all "pros" never installed splitter / guard etc until...
One day ripping a piece of 1/2" ply and trying to catch the outfeed side with my foot or something else stupid and Wham before I knew what happened this piece came spinning back at me like a 100 mph frisbee with sharp points.
To make a long story shorter, after feeling wrong for an hour or so I go to the emergency room to make sure of no internal injuries- Doc tells me that if that point (the corner of the sheet ) had hit me a couple mm further right it would most likely punctured the artery that runs down the inside of your leg and he felt I could have croaked before anyone knew what had happened-
Now I am a avid blade guard / splitter guy and would invest in your KELVAR crotchtal protection garment (can you say crotch on the "net)
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