Table Saw Kickback

[lowell holmes]

I just watched a video made by Kelly Mahler on table saw kickback.
He had the saw blade extended to full height.
I set my blade height at the thickness of the wood and use a push stick. I did cut my thumb one
time and had to go to the emergency room. By limiting the height of the blade, you avoid more
possible exposure. I have had no injuries since then.

Do you have any opinions on this. Just wondering.

[johnny means]

I never consider safety when setting blade height. I set a proper height for the material, then try my best not to put myself in a position to be injured by that blade. The blade height plus one tooth rule is like telling a delivery driver not to drive over 20 mph because the potential for injury is less. Sure it would seem to be safer, but what good is that if it means not being able to do the job in an adequate manner.

[Prashun Patel]

I usually set the blade height so the bottom of the gullet just clears the wood at the blade apex.

I was taught this was a good balance between efficiency of the cut, safety (blade not being too high) and reducing kickback (blade not being too low).

My prejudice is that the bigger danger is kickback because it is not always intuitive: A lower blade height cuts closer to the apex of the blade, where more of the force is forward. A higher blade cuts towards the rear of the blade, where the force is upwards, and has a shorter path to exit.

While I should use a blade guard, I find that it more often than not interferes with my ability to use a push stick or block, so I do not normally use one unless I'm doing a bunch of long rips

[Frank Pratt]

If you're using a guard you can set the blade where ever it will do the best job without compromising safety. Lots of times having the teeth just above the top of the board is not the best height.

[Bruce Page]

I set the blade the same as Prashun, there’s no need to set it higher. I’ve never had a serious kick back, knock wood.

[Bill Space]

[snip]

My prejudice is that the bigger danger is kickback because it is not always intuitive: A lower blade height cuts closer to the apex of the blade, where more of the force is forward. A higher blade cuts towards the rear of the blade, where the force is upwards, and has a shorter path to exit.

[snip]



On my saw a high blade cuts at the front and pushes downward. I am confused by your statement Prashun. Perhaps what you said is not what you meant, or I am not reading it right...

I get what you are saying about the angle of the cut on a low blade. But the cut always occurs at the front half of the blade, if the saw is aligned properly. So I think, anyway...:)

[Pat Barry]

Its a bad idea to have the teeth basically just flush to or slightly above the top of the material being cut. For one thing, the teeth are approaching the material at too low of an angle. This can cause your material to ride up as it moves into the cut. To compensate, you will need excessive downward pressure on the material. Excessive pressure by the operator leads to unsafe conditions, much like a dull knife is blamed for more injuries than sharp ones. Make sure the teeth comfortably clear the material.

[Lee Schierer]

I tend to set the blade higher rather than lower. Only the leading edge of the blade should be doing any cutting if your saw is properly aligned. The teeth at the rear are in the kerf that was cut by the front teeth. The rotation of the blade and cutting action of the teeth is putting downward pressure on the piece being cut, hence a higher blade height puts the down force more directly perpendicular to the table surface. The lower the blade above the top of the wood, the downward force is much less creating the greater the chance the piece will climb up the blade as it is pushed into the blade.

Kick back is a real possibility at any time. It is best to not stand in the potential flight path of the piece being cut if possible. It is also a really good idea to use a splitter or riving knife if your saw has one. Feather boards and hold downs make rip cuts safer, bu can also make he whole process more awkward. Personally I use my Grip Tite feather boards to hold the work against the fence and also hold the trapped piece against the fence behind the blade whenever possible.

Never use a fence and a miter gauge at the same time.

Burn marks on one side of your wood indicate poor alignment.

[jeff norris 2011]

Had kickback once. I was not injured seriously (big bruise) and I have been way more careful for the last 15 years.

As for blade height, I go higher with a guard.

[Rick Potter]

My slider saw has a blade guard in a fixed position on the riving knife. I leave the blade almost fully up, with the guard just clearing the crosscut fence. This leaves little chance for my hand to hit the blade.

On my Unisaw, I set the blade like Lee explained. I use a wood addition to the miter gage to get zero clearance on crosscuts, and push sticks or blocks for rips, which is what I usually use the saw for. Multiple rips, I use the Jessem guides also. They are the best, as they help maintain constant pressure on the work when ripping.

I also had a kickback once on the Unisaw, just before I bought a Beisemier splitter.

[Doug Garson]

Hmmmm 10 posts on kickback and only 2 mention a splitter which in my opinion is the best way to prevent kickback along with a push block that applies pressure to the top of the workpiece. Much more critical that blade height, again my opinion.

[Todd Mason-Darnell]

Hmmmm 10 posts on kickback and only 2 mention a splitter which in my opinion is the best way to prevent kickback along with a push block that applies pressure to the top of the workpiece. Much more critical that blade height, again my opinion.


!00% agree and worry that this thread could turn ugly in a hurry.


I am one for 1 tooth height above. I understand the arguement about the downward force of a higher blade, but at 4800 rpms, I am not sure is there is enough delta in the angle to make a difference.

Also, I thought kickback was cause by the wood contacting the back of the blade.


-Todd

[Will Blick]

I would suggest to moderator to possibly trim or remove some of these posts. Normal confusion can ruin some wood, confusion here can ruin your fingers.

Full agreement, a splitter is the single biggest safety feature to prevent kick back... as the front of the blade does not want to push the wood towards the user.....although if you set your blade low enough, the front of the blade does offer some forward push, hence why higher blade position is safer for kickback. As others have mentioned, a higher blade with no gaurd has more exposure area to hit your hand. So some judgement calls there.

New saws have excllent splitters, making it very very difficult for the wood to strike the rear of the blade. A well made after market splitter should be used on saws that do not have a splitter.

I use crosscut miter gauge with the fence. However, use a 1" block on the fence near the edge of the table. This sets the proper cut distance, as you push the miter guage forward the wood no longer is in contact with the block when the wood hits the blade. Only cause its faster to set my fence vs. my miter gage.

[Vince Shriver]

Hmmmm 10 posts on kickback and only 2 mention a splitter which in my opinion is the best way to prevent kickback along with a push block that applies pressure to the top of the workpiece. Much more critical that blade height, again my opinion.

I agree with Doug; a splitter essentially puts a "fence" between the workpiece and the spinning blade at the tail end of cut where kickback is lurking. Also agree that a push block prevents the workpiece from wondering to the top of the spinning blade and shooting it back. And pushing the piece through the cut while apply nominal pressure against the rip fence goes without saying.

[Prashun Patel]

I said exactly the opposite of what I meant. Sorry: a high blade cuts at the front and wants to push the piece downward.

[Patrick Walsh]

I spend tons of hours behind a tablesaw.

A low blade and kickback definitely coincide with kickback.

I always run a high blade. Not anything silly but not a tooth exposed or any nonsense like that. A good inch or so above the top of the workpiece or more.

As for blade guards and splitters. I think I have seen like a half of person that uses a tablesaw on a daily basis to make a living use either in 20 years. Ok that’s not true but honestly it actually kinda is.

They do both work but are not practical in normal workflow. They also are not needed if you are comfortable competent and mindful.

Good insurance sure.

Use them if that’s what your comfortable with but don’t tell others a thread needs to be closed because they don’t agree.

[Rod Sheridan]

Hi Lowell, there are 3 main methods of preventing kickback.

1) use a splitter or riving knife to prevent the work piece from contacting the rear of the blade.

2) use a crown guard to prevent the work piece from contacting the top of the blade.

3) use a short rip fence that ends just slightly beyond the start of the saw blade.

Regards, Rod

[Edwin Santos]

I haven't noticed anyone else mention one other variable to consider - make sure your miter slot is aligned to the blade and your fence is aligned to the miter slot. If the fence is out of alignment and angled in toward the blade, even very slightly, as in a few thousandths, in my experience the potential for kickback increases substantially, regardless of where the blade height is set.

Another thing to watch out for is tension in wood that might cause it to pinch the blade. This is another case for a splitter or riving knife.

I don't personally believe that table saw blade height is a major factor in kickback. Table saw blades vary quite a bit and the correct blade height for one tooth geometry might be different for another anyway.

Honestly, I feel the bandsaw is much safer and more pleasant way to rip hardwood, but if one insisted on using a table saw, the suggestions in this thread are good precautions.

[Doug Garson]

Hi Lowell, there are 3 main methods of preventing kickback.

1) use a splitter or riving knife to prevent the work piece from contacting the rear of the blade.

2) use a crown guard to prevent the work piece from contacting the top of the blade.

3) use a short rip fence that ends just slightly beyond the start of the saw blade.

Regards, Rod
Rod, I agree 100% with 1 & 3 but I don't understand #2, I agree it prevents your hand from contacting the blade, not sure how it prevents workpiece from contacting top of blade, please enlighten me.

[Ben Schmidt]

I spend tons of hours behind a tablesaw.

A low blade and kickback definitely coincide with kickback.

I always run a high blade. Not anything silly but not a tooth exposed or any nonsense like that. A good inch or so above the top of the workpiece or more.

As for blade guards and splitters. I think I have seen like a half of person that uses a tablesaw on a daily basis to make a living use either in 20 years. Ok that’s not true but honestly it actually kinda is.

They do both work but are not practical in normal workflow. They also are not needed if you are comfortable competent and mindful.

Good insurance sure.

Use them if that’s what your comfortable with but don’t tell others a thread needs to be closed because they don’t agree.

A low blade and kickback coincide with kickback? Could you clarify?

Also, what is it about a riving knife that is not practical in normal workflow? Blade guard sure, but I fail to see how a riving knife gets in the way of working on a table saw.

[Steve Eure]

In all the responses, no one has mentioned anything about anti-kickback pawls that are on new saws. Does anyone use them, or just discard them when they get their new saw. As far as blade height, both of my saws have to have the blade higher than I like when using the guard. So if the engineers designed it this way, maybe the blade needs to be a little higher than what I usually run my saw at. I have always been told the gullets should be just at the top of the material being cut. But again, if the guard is on, that point is mute.

[Rod Sheridan]

Hi Doug, the crown guard covers the top of the blade, you can’t have a piece of wood touch that area of the blade as it’s covered.

Obviously if a piece of contacted the top of the blade it would be ejected towards the operator....Rod

[Rod Sheridan]

Hi Steve, the anti-kickback pawls are not used on many table saws.

They’re not usable on non through cuts whereas the 3 standard safety devices are....Rod

[Jacob Reverb]

Don't stand behind the blade. :cool:

[Phil Mueller]

Another thing to keep in mind is that my saw came with a riving knife that was designed for a standard kerf (1/8”) saw blade. It won’t work with a thin kerf blade and gets removed when one is used. Just something to check if you change blade thickness.

[Ole Anderson]

A tooth above user here. And I always breathe a sigh of relief when the board reaches the splitter. I use a Sharkguard on my G1023 whenever possible, not just safety, but dust collection. And never rip a square block of wood, asking for kickback as the wood may never reach the splitter/riving knife. Exception would be sheet goods where you can keep both hands on the work.

[Lee Schierer]

Hi Steve, the anti-kickback pawls are not used on many table saws.

They’re not usable on non through cuts whereas the 3 standard safety devices are....Rod

Riving Knives and splitters cannot be used on non-through cuts either as they stick up higher than the top of the teeth.

[mike stenson]

Riving Knives and splitters cannot be used on non-through cuts either as they stick up higher than the top of the teeth.

Splitters sure, but all the actual riving knives I've seen can be left for non-through cuts.

[glenn bradley]

Splitters sure, but all the actual riving knives I've seen can be left for non-through cuts.

There are certainly a number of saws out there where the RK has been morphed to hold a guard or pawls and no longer functions like an RK. Kickback danger is reduced by an RK. Cuts that free a keeper or a spoil piece before the RK is engaged can still get launched. There is not universal rule for tablesaw safety. I set my blade height for the operation I am performing. In general I clear the gullet by a bit. For veneers I set the blade higher to adjust the geometry of the tooth path. For joinery operations the blade height is part of the joints profile and is set to the height required for the cut; tenons, rabbets, finger joints, etc.

[Mike Goetzke]

Wow! With the possibility of a life changing accident I can't believe after reading through these posts how many do not use a blade guard or splitter. I have a Shark Guard - the bonus is you get top of saw dust collection. I also use a set of clear-cut TS stock guides. I know there are some cuts that makes some of these safety features unusable but it takes maybe 30 seconds to put the splitter and/or blade guard back on and probably another 30 seconds to set up the stock guides. Some times it does slow you down a bit because the push stick may not have a super clear path but well worth it to work safely.

OP - I too like others set the blade gullet right at or just above the wood.


Mike

[lowell holmes]

I have 10" Delta Contractors Saw that I made a wood insert with a splitter on it. I have no kickbacks.

[Brian Deakin]

Members may find the links below interesting they are information sheets from the UK Health and Safety executive

https://www.hse.gov.uk/pubns/wis16.pdf

https://www.hse.gov.uk/pubns/circular-saw.pdf

https://www.hse.gov.uk/woodworking/ripsaw.htm

https://www.hse.gov.uk/woodworking/wis.htm

[Brian Deakin]

Members may find the links below interesting they are information sheets from the UK Health and Safety executive

https://www.hse.gov.uk/pubns/wis16.pdf

https://www.hse.gov.uk/pubns/circular-saw.pdf

https://www.hse.gov.uk/woodworking/ripsaw.htm

https://www.hse.gov.uk/woodworking/wis.htm

[Mike Goetzke]

I have 10" Delta Contractors Saw that I made a wood insert with a splitter on it. I have no kickbacks.

How about a blade guard?

[Doug Garson]

Hi Doug, the crown guard covers the top of the blade, you can’t have a piece of wood touch that area of the blade as it’s covered.

Obviously if a piece of contacted the top of the blade it would be ejected towards the operator....Rod
Agree Rod, but the piece of wood would never touch the top of the blade in the normal way we use a table saw only if we accidently dropped it on a spinning blade.

[mike stenson]

Agree Rod, but the piece of wood would never touch the top of the blade in the normal way we use a table saw only if we accidently dropped it on a spinning blade.

I've seen thin stock, especially, grab the back of the blade and ride up. A crown guard would prevent that too.

[Rod Sheridan]

Agree Rod, but the piece of wood would never touch the top of the blade in the normal way we use a table saw only if we accidently dropped it on a spinning blade.

Hi, Mike Stenson replied regarding this as well, the work piece can ride up the blade and contact the top of the blade.

That's the entire purpose of the crown guard, preventing objects from contacting the top of the blade.............Regards, Rod.

[lowell holmes]

I use push sticks and never get close to the blade. I also wear safety glasses.

[Pat Barry]

Hi Lowell, there are 3 main methods of preventing kickback.

1) use a splitter or riving knife to prevent the work piece from contacting the rear of the blade.

2) use a crown guard to prevent the work piece from contacting the top of the blade.

3) use a short rip fence that ends just slightly beyond the start of the saw blade.

Regards, Rod

Sorry Rod. What is a crown guard? Can you provide a picture or references?

[ChrisA Edwards]

Sorry Rod. What is a crown guard? Can you provide a picture or references?

I had to look it up also....


https://www.youtube.com/watch?v=yRyZ7OCZ-Vc

[Doug Garson]

I use push sticks and never get close to the blade. I also wear safety glasses.
None of these prevent kickback. All are good practice.

[Mike Kees]

I disagree Doug. there are two distinct types of kickback. 1. long narrow stock pinches either around the blade or between blade and fence and shoots out the rear of saw. 2. sheet goods in dimensions close to square shape are not controlled and lift slightly and "catch the edge of the blade and then spin as the blade digs in from underneath and launches them. A good push stick design will hold the later (type 2) down tight on the table and help greatly in preventing this type from happening. I think that riving knives are probably one of the best table saw safety devices out there for the best protection for type 1 kickbacks.

[Doug Garson]

Agree with your comment on riving knife, on the push stick I think what you call a push stick I call a push block and a quick Google search seems to show you are in the majority. Can't seem to cut and paste an image from Google to show what I mean but I call the type which puts pressure on the top a push block, I call a push stick the type that just pushes the trailing edge of the workpiece. Kinda hard to describe without a picture.

[Pat Barry]

I hate using a push stick. I just don't feel comfortable with having so little control. I like the 'shoe' style, which gives the operator the ability to apply downward pressure to the material.

[Brian Holcombe]

The pad-style push blocks give me pause, they cause the operator to push the material over the blade. It's my understanding that kick-back is entirely more dangerous (it is always dangerous) if you're physically extended past the blade. A kickback at that position increases the likelihood of the operator traveling over the blade, which is a situation I would personally want to avoid.

I don't use a tablesaw for rip cutting, very much at all. I have a bandsaw and a planer so I'm happily making parallel edges with machinery more suited to it. I'll use the tablesaw mainly for ripping wide panels when the need arises.

Skinny pieces and short pieces are dangerous.

[John K Jordan]

I tend to set the blade higher rather than lower. Only the leading edge of the blade should be doing any cutting if your saw is properly aligned. The teeth at the rear are in the kerf that was cut by the front teeth. The rotation of the blade and cutting action of the teeth is putting downward pressure on the piece being cut, hence a higher blade height puts the down force more directly perpendicular to the table surface. The lower the blade above the top of the wood, the downward force is much less creating the greater the chance the piece will climb up the blade as it is pushed into the blade.


That is exactly how I was taught. Teeth just clearing the top of the wood direct any force at the cutting point forward. Teeth angling down from above the blade direct that force more towards the table. Of course, the kerf the back of the blade rides in must be constrained from pinching and causing the wood to rise, with alignment, technique, splitters, hold-downs, guards, and wood choice. If the idea of a low blade is to reduce tooth exposure to minimize damage to fingers i suspect safety efforts might be better directed elsewhere.

The extreme example of downward cutting force is the bandsaw. Bandsaws have their own safety issues but kickback isn't on the list.

[Corey Pelton]

I use the Jessem clear cut guides, though I've never had an issue with any kickback on my saw. The guides are great for keeping the work tight to the fence and the table.

[Norman Pirollo]

I've been following this thread and when I hear kickback, my ears perk up. Experienced it 2-3X many years back and made it a mission to understand it fully. Otherwise, I would not be comfortable using my 3HP Unisaw. So I always use a splitter when ripping (with pawls). This in itself can stop kickback. Ensure fence is aligned correctly to blade. On crosscuts where fence is necessary for repeatability, only have a partial fence that ends at front of blade. I also use a sled often, feel it's safer using this. Also never stand directly behind the saw blade (line of fire). So I take all the precautions.

Having said this, I went further with this and developed an anti-kickback system for table saws. I spent last fall developing it and it works. It just needs to be integrated into new models of table saws, so hoping to have manufacturers jump on board. It dynamically brakes the blade in kickback situations. The momentum of the blade is dissipated enough to eliminate the force of kickback. There is a demonstration of it in a YouTube video for those interested. I wear gloves and safety glasses only for the demo and stand completely to the side as well ( for demonstration purposes).



https://www.youtube.com/watch?v=oHlJNb86gLM

Enjoy,
Norman

[Patrick Walsh]

Oh sigh....

Skinny pieces are dangerous come on. Throw a zero clearance insert in “if that” and get some work done..

Omg this topic is exhausting.

I’m half poking at you cuz I feel I can. The other half is actually telling you how I feel.

Sure tablesaw are dangerous. So aren’t most Woodworking machines. I’m not suggesting to be reckless but I just don’t get the safety you no what’s. Imop fear is more dangerous than anything maybe even stupidity.

So many things one can partake in “risky behavior or ventures” fear must be overcome. And before anyone saiz it a healthy respect and knowledge must still be applied, stupidly can take the place of fear.

All Im saying is it never seeses to amaze me how many people are truly afraid of tools. It’s like how can you not get over something you do ever day at some point.

And sorry a tablesaw is pretty darn precise for ripping stock if well setup and you don’t use a push stick for every cut. And when it’s not and if precision is that important surfaced four sides is the only real answer.

Call me stupid and I’m sure many do but there times I’m so committed to my workpiece being the hours I have into it that taking a slight risk with my body is worth it to me. A knowledge of how wood and machines react and how to balance counteract and predict these situations takes one a long way to avoiding accidents. But if you’re always scared you’ll never get there and accidents imop that much more prone.

I apologize Brian for dropping this in response to you lol..

But not really.


The pad-style push blocks give me pause, they cause the operator to push the material over the blade. It's my understanding that kick-back is entirely more dangerous (it is always dangerous) if you're physically extended past the blade. A kickback at that position increases the likelihood of the operator traveling over the blade, which is a situation I would personally want to avoid.

I don't use a tablesaw for rip cutting, very much at all. I have a bandsaw and a planer so I'm happily making parallel edges with machinery more suited to it. I'll use the tablesaw mainly for ripping wide panels when the need arises.

Skinny pieces and short pieces are dangerous.

[Brian Holcombe]

Just be glad I’m not afraid of milling machines :D

I make kumiko and I know some people who use a tablesaw to bring it to thickness, I use a planer and every joint fits identically when complete.

[Patrick Walsh]

Well using a table saw to dimension for such a task is kinda ridiculous.

Not because of the danger but because of as you said the fit.

Even large material I insist in surfaced and sanded four sides as anything else is just futile regarding ease of executing reliable repeatable and clean work..

No I’m just lucky u have one and will entertain my nonsense..

[J.R. Rutter]

I just set blade height low initially and as the zero clearance insert wears, it gets raised so that it is cutting fresh at the tip of the carbide teeth. Riving knife and overarm blade guard though...

[Carlos Alvarez]

I've had a few mild to major kicks, all before I learned how to perfectly align a saw. That was almost ten years ago, and not a single incident since then. I spent close to two hours aligning every single part to within 1/256th and now there's no drama, much less friction, much less noise, no burning edges.

[Pat Barry]

I've had a few mild to major kicks, all before I learned how to perfectly align a saw. That was almost ten years ago, and not a single incident since then. I spent close to two hours aligning every single part to within 1/256th and now there's no drama, much less friction, much less noise, no burning edges.

You can do all the alignment in the world and that won't help when it comes to ripping a board that wants to grab the blade.

[Brian Holcombe]

Yes, and you can use a bandsaw for those board.

[Carlos Alvarez]

You can do all the alignment in the world and that won't help when it comes to ripping a board that wants to grab the blade.

The alignment prevents the board from wanting to grab the blade. 100% so far for me.

[Frank Pratt]

The alignment prevents the board from wanting to grab the blade. 100% so far for me.

That's actually a dangerous conception to have, but the "so far" part you've got right. Yes, perfect alignment can reduce the incidence of kick back, but not nearly as much as using a riving knife/splitter and guard, and most importantly, user technique. Even all that may not save you if you get a crazy piece of reaction wood.

[Carlos Alvarez]

That's actually a dangerous conception to have, but the "so far" part you've got right. Yes, perfect alignment can reduce the incidence of kick back, but not nearly as much as using a riving knife/splitter and guard, and most importantly, user technique. Even all that may not save you if you get a crazy piece of reaction wood.

All of these things are important together. WITH the splitter and guard, I still had some kicks before I aligned the saw. Misalignment probably starts the problem, the others are still important. I've never cut without the splitter, and almost never without the guard.

[Patrick Walsh]

Ok I’m gonna have to argue about this.

Sure any tool/machine can be used for a myriad of tasks but if a table saw is not suited towards ripping I don’t know what it’s really for.

Any you don’t have to name off a list for me as I full well know the variety of tasks a tablesaw serves.

Ripping on a bandsaw safer ok but better suited sure if you have a nice enough saw that the blade does not defect on iota. I know even a tablesaw with a regular blade I’ll often run a blade surfer to reduce defection and that’s 1/8 thick 10” blade not some rinky dinky bandsaw blade on some rinky dinky bandsaw. Now if you have a pro level or rather I should say industrial level bandsaw fine but most don’t.

As for toe in and toe out. Sure that’s one potential cause but far from a across the board solution or cure. If you think so you surely have not spent much time behind a tablesaw to experience the myriad of situations that can create kickback. The most simple is tension in a board. Often this tension let’s loose without much of any warning and when it does you had best have nerves of steel and laser focus as to not flinch and cut your hand off.

But again. If a tablesaw is not better suited to ripping lumber well then a bandsaw well then I must not know how to use a bandsaw and I actually do and I have a very nice and capable. I prefer to rip on the tablesaw and I guess part of it is I’m just not the slightest scared of pretty much any machine.

When I climbed ice, Rick and alpine mountains it was a common knowledge that fear meant you were in over you head or operating outside of the boundaries of your abilities. I’m not suggesting that be the case for anyone here and surely not you Brian but I think the theory kinda holds water in most but not all cases.

As oppinion Ted as I am on the topic this is Woodworking and everyone should do what they feel safe doing and what they enjoy doing as the whole thing is about enjoying at the end of the day.

[Derek Cohen]

I’ve always viewed kickback as having a singular cause - when the workpiece contacts the rear of the saw blade, which then causes it to climb up the blade. This is explained and demonstrated very well by Roland Johnson in a video by Fine Woodworking: https://www.finewoodworking.com/2008/11/01/fight-kickback-with-a-riving-knife

Preventing kickback should be very simple - just do not allow the workpiece touch the back of the blade. A riving knife should do this. However, in practice there are other factors to consider. For example, one cannot use a riving knife when sawing blind cuts, such as grooves.

I generally keep the blade high for two reasons. The first is that this ensures that the riving knife is always high enough - a low blade has a yet lower riving knife, and the workpiece can move over it into the blade. The second reason is that the angle of the teeth is more vertical, and this does not allow the workpiece to climb over the blade and shoot forward, as it can with a low blade.

All is not safe yet. I have a Hammer K3 (slider). Kickback is highly unlikely (in my understanding/experience here) when ripping on the slider, where the workpiece is fixed and the off-cut runs parallel to the cut. Kickback is more a feature of ripping against a rip fence, where the workpiece may be forced into the blade.

When using the rip fence, I have noted how a workpiece may be lifted and ejected. I have been puzzling why this occurs, and the reason I have come up with is that the blade cuts a fine kerf, and that the ejection is a milder version of kickback - that is, the teeth at the rear of the blade can lift the workpiece. This is controlled when ripping on the slider as the workpiece is secured at the front and rear. But I use the rip fence as well (mine is a shorter, 49” slider). I added a finger board to the fence, and this has stopped any lifting ...

https://i.postimg.cc/8z0M2bX1/K3-1a.jpg

As a result if this thread, I revisited my thoughts on the dynamics of ripping and recognised that the rip fence can do more. There is the obvious issue of a fence that is poorly aligned with the blade and will push the workpiece across and into it. That is not my concern. Instead, what I wanted was to ensure that the side of the workpiece stayed tightly to the rip fence and did not wander off it, which is largely down to operator error (how we push, and from what angle we do so). The finger board does not control this. All it does is hold down the workpiece.

In my surfing the Net, I again came across the JessEm Clear cut Saw Guides, and now understood them better. These not only hold the work down and prevent it from moving backwards, but importantly also force the workpiece into the side of the rip fence.

https://i.postimg.cc/vZfhtpHp/C4E7DE0A-1A32-4D18-80DB-8FEC818A6DF3.png

Expensive, but I caught a discounted special, and ordered a set. It is on its way, so not feedback as yet. At the least, I expect cleaner cut when using the rip fence. Plus it should make blind cuts much safer.

Regards from

Derek

[Frank Pratt]

All of these things are important together. WITH the splitter and guard, I still had some kicks before I aligned the saw. Misalignment probably starts the problem, the others are still important. I've never cut without the splitter, and almost never without the guard.

Glad you clarified that Carlos.:)

[Doug Garson]

I’ve always viewed kickback as having a singular cause - when the workpiece contacts the rear of the saw blade, which then causes it to climb up the blade. This is explained and demonstrated very well by Roland Johnson in a video by Fine Woodworking: https://www.finewoodworking.com/2008/11/01/fight-kickback-with-a-riving-knife

Preventing kickback should be very simple - just do not allow the workpiece touch the back of the blade. A riving knife should do this. However, in practice there are other factors to consider. For example, one cannot use a riving knife when sawing blind cuts, such as grooves.

I generally keep the blade high for two reasons. The first is that this ensures that the riving knife is always high enough - a low blade has a yet lower riving knife, and the workpiece can move over it into the blade. The second reason is that the angle of the teeth is more vertical, and this does not allow the workpiece to climb over the blade and shoot forward, as it can with a low blade.

All is not safe yet. I have a Hammer K3 (slider). Kickback is highly unlikely (in my understanding/experience here) when ripping on the slider, where the workpiece is fixed and the off-cut runs parallel to the cut. Kickback is more a feature of ripping against a rip fence, where the workpiece may be forced into the blade.

When using the rip fence, I have noted how a workpiece may be lifted and ejected. I have been puzzling why this occurs, and the reason I have come up with is that the blade cuts a fine kerf, and that the ejection is a milder version of kickback - that is, the teeth at the rear of the blade can lift the workpiece. This is controlled when ripping on the slider as the workpiece is secured at the front and rear. But I use the rip fence as well (mine is a shorter, 49” slider). I added a finger board to the fence, and this has stopped any lifting ...

https://i.postimg.cc/8z0M2bX1/K3-1a.jpg

As a result if this thread, I revisited my thoughts on the dynamics of ripping and recognised that the rip fence can do more. There is the obvious issue of a fence that is poorly aligned with the blade and will push the workpiece across and into it. That is not my concern. Instead, what I wanted was to ensure that the side of the workpiece stayed tightly to the rip fence and did not wander off it, which is largely down to operator error (how we push, and from what angle we do so). The finger board does not control this. All it does is hold down the workpiece.

In my surfing the Net, I again came across the JessEm Clear cut Saw Guides, and now understood them better. These not only hold the work down and prevent it from moving backwards, but importantly also force the workpiece into the side of the rip fence.

https://i.postimg.cc/vZfhtpHp/C4E7DE0A-1A32-4D18-80DB-8FEC818A6DF3.png

Expensive, but I caught a discounted special, and ordered a set. It is on its way, so not feedback as yet. At the least, I expect cleaner cut when using the rip fence. Plus it should make blind cuts much safer.

Regards from

Derek
Well said, I agree with all you said except why do you say you cannot use a riving knife with "blind cuts AKA non thru cuts? Doesn't a riving knife move up and down with the blade so it is always below the top of the blade and thus can be used with non thru cuts? Did you mean to say splitter which has a fixed height?

[Derek Cohen]

Well said, I agree with all you said except why do you say you cannot use a riving knife with "blind cuts AKA non thru cuts? Doesn't a riving knife move up and down with the blade so it is always below the top of the blade and thus can be used with non thru cuts? Did you mean to say splitter which has a fixed height?

Doug, the riving knife does move with the blade. However, it is generally set a little below the top of the blade. It cannot be set above the blade for blind cuts, of course. Some like to set it low enough to wind down the blade and have enough free above the riving knife to make blind cuts. With a blind cut, setting it lower effectively removes the riving knife and enables the workpiece to contact the back of the blade. Setting it level with the top of the blade should prevent this. I wonder how many table saws allow this. Many I have seen make it difficult owing to the design of the riving knife - consequently, the riving knife is either low or high. Some report removing the riving knife owing to the latter.

Regards from Perth

Derek

[Mark e Kessler]

I have never had or seen one set above the blade, the main purpose of the riving knife is to prevent the wood from pinching on the back of the blade and ejecting


Riving Knives and splitters cannot be used on non-through cuts either as they stick up higher than the top of the teeth.

[Mark e Kessler]

The other thing I never see mentioned (well probably mentioned at some point somewhere...) here when a kickback/blade height discussion occurs is how sharp the blade is, I have noticed that responses that state something like “i set the blade high” , “1” taller than work piece” ect will almost always be individuals that have worked in commercial shops where the blade in the saw is more likely to be on the dull side than the sharp side, a dull blade is a dangerous one, if to low can lift a board up ( swear never happened to me) i just don’t like a blade too low super dangerous in my opinion, too low being 1 tooth or whatever the magazines/books recommend...

[johnny means]

Hmmm, I wouldn't have imagined a discussion about blade height setting without a single mention of cut quality or tearout/chipout. That's the only real factor, as far as I'm concerned.

[Brian Holcombe]

We can never make it past safety. Safety is interesting to an extent, but it’s well covered here. I generally raise the blade up but rely upon blade choice to make a high quality cut.

[Patrick Walsh]

Another valid instance that creates or lends itself to kickback Mr. Kessler

There really are many tbh.

I think what matters most in regard to kickback is not precautions but awareness and the hands on experience and capacity for one to recognize something going sideways as it is going sideways and the experience to react appropriately.

Sure if you swim with sharks chances are sooner or later you get bitten but a in depth understanding of your environment and the subject goes a long way towards avoiding gettin bitten.

Sharks aren’t bad nor are tablesaw shapers yada yada.

You just gotta take it slow be honest and develop a relationship with your machinery.

That’s takes time, hours upon hours behind these machines experimenting with different approaches used for similar and different tasks.

Like anything in life you will succeed and fail. Hopefully when u fail u don’t loose a extremity but if you do I get you learn something you didn’t know prior. Hopefully your smart enough to recognize what does not work before there is a consequence but you know somethings can only be learnt i the physical form.

Nothing in life is without risk. It’s just some risk “our bs minds or ignorance” or what I like to think of as conditioned minds rationalize better than others. That imop is the most dangerous.

I’ll take shop risks or the risks presented in nature “say the mountains” over those out in the populated world counting on the masses to make good decisions.

You know like driving..

Sorry I typed that in a Whole Foods parking lot in my phone so the typos where even worse than worse lol.. as if they could be hahahah


https://www.youtube.com/watch?v=2UFc1pr2yUU

[Mark Hennebury]

Well put Patrick, 100%


Another valid instance that creates or lends itself to kickback.

There really are many tbh.

I think what matters most in regard to kickback is not precautions but awareness and the hands in experience snd capacity to recognize something going sideways as it is going sideways and the experience to react appropriately.

Sure if you swim with sharks chances are sooner or later you get bitten but a in depth understanding of your environment and subject goes a long way towards avoiding gettin bitten.

Sharks aren’t bad nor are tank saws shapers yada yada.

You just gotta take it slow be honest and develop a relationship with your machinery.

That’s takes time hours upon hours behind them experimenting with different approaches used to similar and different tasks.

Like anything in life you will succeed and fail. Hopefully when u fail u dint loose a extremity but if you do I get you learn something you didn’t know prior.

Nothing in life is without risk. It’s just some risk our bs it ignorant or what I like to think conditioned minds rationalize better than others.

I’ll take shop risks or the risks presented in nature “say the mountains” over those out in the populated world counting in the masses to make good decisions.

You know like driving..

[Bill Space]

Doug, the riving knife does move with the blade. However, it is generally set a little below the top of the blade. It cannot be set above the blade for blind cuts, of course. Some like to set it low enough to wind down the blade and have enough free above the riving knife to make blind cuts. With a blind cut, setting it lower effectively removes the riving knife and enables the workpiece to contact the back of the blade. Setting it level with the top of the blade should prevent this. I wonder how many table saws allow this. Many I have seen make it difficult owing to the design of the riving knife - consequently, the riving knife is either low or high. Some report removing the riving knife owing to the latter.

Regards from Perth

Derek

I am missing something here. My riving knife is set very slightly below the apex of the blade, but not by much. Never measured it. Could be several thousandths or perhaps a little more.

It always maintains this position with respect to the blade regardless of blade height setting. Seems like the action of the riving knife is the same whether making a through cut or a blind cut...

[Doug Garson]

I am missing something here. My riving knife is set very slightly below the apex of the blade, but not by much. Never measured it. Could be several thousandths or perhaps a little more.

It always maintains this position with respect to the blade regardless of blade height setting. Seems like the action of the riving knife is the same whether making a through cut or a blind cut...
Don't have a riving knife on my saw but that is my understanding of how they are supposed to work and thus my original comment.

[Derek Cohen]

I am missing something here. ...

It always maintains this position with respect to the blade regardless of blade height setting. Seems like the action of the riving knife is the same whether making a through cut or a blind cut...

Bill, in my reasoning, there are two actions, not one.

In a through cut, the blade and riving knife may be set high ... much higher than the workpiece. The riving knife will ensure that the workpiece does not touch the blade.

In a blind cut, with a lowered riving knife, the workpiece must touch the top of the blade to cut (naturally). It is this lower cutting angle that is more likely to propel it forward, and if conditions are tight for kickback, it can occur. Blinding in the cut is one condition.

Regards from Perth

Derek

[J.R. Rutter]

Hmmm, I wouldn't have imagined a discussion about blade height setting without a single mention of cut quality or tearout/chipout. That's the only real factor, as far as I'm concerned.


I just set blade height low initially and as the zero clearance insert wears, it gets raised so that it is cutting fresh at the tip of the carbide teeth. Riving knife and overarm blade guard though...

That's kinda what I was getting at.

[Dan Jansen]

Don't stand behind the blade. :cool:

Sometimes it takes a shot in belly to learn this lesson. It was an odd place to have a bruise. I once dented a steel door 20 feet away. Fortunately, I already learned to not stand behind the blade (the hard way of course).

I have a hunch most kickbacks come from a fence pinching the material because the fence isn’t parallel to the blade.

Learning a feel for when to not push it helps too but takes time. I recently had a bad SYP 2x8 that actually pinched the miter saw blade so tight I had to remove the blade from the saw to get enough leverage to free the blade. I safely ripped it after that but was very alert.

[Patrick Walsh]

https://www.youtube.com/watch?v=3KBGv-LCKeg

[Patrick Walsh]

If you make sense of the subject like these guys...

https://www.youtube.com/watch?v=3KBGv-LCKeg

[Edwin Santos]

Oh sigh....



Sure tablesaw are dangerous. So aren’t most Woodworking machines. I’m not suggesting to be reckless but I just don’t get the safety you no what’s. Imop fear is more dangerous than anything maybe even stupidity.

So many things one can partake in “risky behavior or ventures” fear must be overcome. And before anyone saiz it a healthy respect and knowledge must still be applied, stupidly can take the place of fear.

All Im saying is it never seeses to amaze me how many people are truly afraid of tools. It’s like how can you not get over something you do ever day at some point.





Ok I’m gonna have to argue about this.

I prefer to rip on the tablesaw and I guess part of it is I’m just not the slightest scared of pretty much any machine.

When I climbed ice, Rick and alpine mountains it was a common knowledge that fear meant you were in over you head or operating outside of the boundaries of your abilities. I’m not suggesting that be the case for anyone here and surely not you Brian but I think the theory kinda holds water in most but not all cases.

As oppinion Ted as I am on the topic this is Woodworking and everyone should do what they feel safe doing and what they enjoy doing as the whole thing is about enjoying at the end of the day.

Ah the English language. Words can have so many subtle differences in meaning. Scared? I agree with you, not so good to be debilitated by fear.
But cautious? Maybe not so bad

So where does a given woodworker fall on the spectrum: Scared>Somewhat Frightened>Cautious>Supremely Confident>Fearlessly Macho

I've known a few woodworkers with missing digits and most of them sort of wore the last category or two like a badge. Of course their accidents were always due to factors that were not their fault. These guys are usually rabbits more than tortoises. If I may say so, maybe a dose of caution might have been in order.

I've also known some veteran woodworkers with all their digits and not a scar to show for. Those guys were closer to the middle and maybe even slightly left. They usually have patient methodical personalities. In other words, tortoises. Not so much in terms of speed but in terms of mentality and attitude.

My opinion - no shame in being a cautious (or maybe "cautiously confident") woodworker, and while I guess any subject can be over-discussed and over-analyzed, there are worse sins than discussing why machine accidents happen and how to prevent them. Maybe not a bad idea to watch others and study others' habits and make your own decision about where on the spectrum you'd like to be.

Edwin

[Patrick Walsh]

Ed,

So we are saying the same thing.

The only differing of opinion would be my being annoyed by people whom interject their belief systems upon me others or the masses.

You know like that guy that always has something to say about how the other guy uses machines. Or that guy that always corrects your spelling knowing full well you can’t spell and never will be able to, or that guy that insists on correcting your grammar even though he knows you will never get it.

Or that guy that pretty much has to tell everyone how to do everything exactly like they do it.

That guy well that guy I’ll always speak up to in defense of myself.

I used to have this friend. He was a relentless recycler. I am also to be perfectly honest. But he was totally anti tin foil and anti styrofoam. You know I get it and for good reason. Much like straws they can’t be recycled and end up in a landfill for eternity.

Anyway I will sparingly use tin foil, whenever he would eat over if he ever saw a piece of tin foil I would hear about it. God forbid I threw it away he would fish it out of my trash. He would take it home with him and then reuse it for a multitude of purposes till it literally disintegrated. This was one of those guys I would come to figure out was unable and Unwilling to do anything anyone’s way but his own to the upteenth degree. He also corrected my spelling my grammar and on group bike rides would tell everyone how to ride there bike and where we would be going specifically each and every ride. Don’t want to wear a helmet he wouldn’t ride with you.

Point is have come across a number of these guys in my life. Often times these guys are also the workshop safety guys. You know, know it all types or complete herbs. I don’t say the last to be derogatory or anything full well knowing it is derogatory but to paint a picture as to my complete and total lack of tolerance I have for this type.

FYI I have all my fingers, if am anything I am the slow methodical executed type.

I’m also the come on guys get some dam work done type but you know..

But still I feel you and I are saying the same thing. Caution is not bad, fear is I would say, healthy respect not so much. Insisting others do as you do crazy super annoying.




Ah the English language. Words can have so many subtle differences in meaning. Scared? I agree with you, not so good to be debilitated by fear.
But cautious? Maybe not so bad

So where does a given woodworker fall on the spectrum: Scared>Somewhat Frightened>Cautious>Supremely Confident>Fearlessly Macho

I've known a few woodworkers with missing digits and most of them sort of wore the last category or two like a badge. Of course their accidents were always due to factors that were not their fault. These guys are usually rabbits more than tortoises. If I may say so, maybe a dose of caution might have been in order.

I've also known some veteran woodworkers with all their digits and not a scar to show for. Those guys were closer to the middle and maybe even slightly left. They usually have patient methodical personalities. In other words, tortoises. Not so much in terms of speed but in terms of mentality and attitude.

My opinion - no shame in being a cautious (or maybe "cautiously confident") woodworker, and while I guess any subject can be over-discussed and over-analyzed, there are worse sins than discussing why machine accidents happen and how to prevent them. Maybe not a bad idea to watch others and study others' habits and make your own decision about where on the spectrum you'd like to be.

Edwin

[johnny means]

I've also known some veteran woodworkers with all their digits and not a scar to show for. Those guys were closer to the middle and maybe even slightly left. They usually have patient methodical personalities. In other words, tortoises. Not so much in terms of speed but in terms of mentality and attitude.



Edwin

After twenty+ years, I definitely see myself in this group. I was lucky enough to survive my early years with zero accidents. I try to to teach the young guys that 50 well planned cuts is both faster and safer than 100 rushed cuts.

[Edwin Santos]

Ed,



Point is have come across a number of these guys in my life. Often times these guys are also the workshop safety guys. You know know it all types or complete herbs. I don’t say the last to be derogatory or anything but I know it is but to paint a picture as to my complete and total lack of tolerance for the type.



Cool that we agree. But dude, what are complete herbs? I swear I'm not being a spelling nazi or wise guy know it all. I'm genuinely into vernacular.
I even googled it, but all that came up was a business called Herb's Complete Auto Repair.

Again, totally agree with you that none of us should force our workshop beliefs on others. Except maybe in the case of an employer who is enforcing safety for insurance and liability reasons. I can understand that.

Ed

[Patrick Walsh]

100% agree on the boss. I was thinking it as I typed what I was saying but figured why go off on another tangent distracting from my message.

Hold on I’ll try and find a example of herb.


Cool that we agree. But dude, what are complete herbs? I swear I'm not being a spelling nazi or wise guy know it all. I'm genuinely into vernacular.
I even googled it, but all that came up was a business called Herb's Complete Auto Repair.

Again, totally agree with you that none of us should force our workshop beliefs on others. Except maybe in the case of an employer who is enforcing safety for insurance and liability reasons. I can understand that.

Ed

[Patrick Walsh]

https://www.urbandictionary.com/define.php?term=Herb

[Edwin Santos]

https://www.urbandictionary.com/define.php?term=Herb

LOL, this basically means I'm one for needing to have it defined.......

Oh well, there's not much of my ego left anyway,
But at least I learned something new
Ed

[Patrick Walsh]

Oh come on give yourself a break.

Your probably just not like twenty lol..

Worse things to be but....


LOL, this basically means I'm one for needing to have it defined.......

Oh well, there's not much of my ego left anyway,
But at least I learned something new
Ed

[lowell holmes]

I have a splitter on my saw. I made a wooden insert with a splitter on it.

It works.

[Andrew Pitonyak]

By limiting the height of the blade, you avoid more
possible exposure. I have had no injuries since then.

Do you have any opinions on this. Just wondering.

I like to set the saw blade based on how high it needs to be to make the cut and safety. For certain, not clearing the blade by much will limit exposure. On the other hand, my last kickback occurred while cutting a dado. Luckily I strongly controlled the kickback, but it still hurt.

I think that using other safety features are a huge help; for example, a riven knife.

As for blade height, however, it is my understanding that changing the height changes the angle of attack of the blade when it cuts and you can affect the quality of cut, especially in plywood. That said, I found that my plywood blade seems to do a good job regardless.