Table-Saw Kickback on Camera (2012) [video]
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The origin of SawStop is quite a cool story. The founder and inventor created this auto-stop saw, and tried to sell the tech to all the major saw manufacturers. No company would buy it because they didn't think there was a market, so he started a company around it which is disrupting the entire market.
In contrast, variants of sliding table saws are the norm in Europe and elsewhere. These are common in the US as panel saws for cutting sheet goods, but also come in much smaller sizes which are often better for smaller shops and solid wood-based applications. The workholding is different: a slider and a few standard accessories eliminates the need for crosscut sleds, common jigs, and a whole display of gripping-things at your local Woodcraft. The operator stands to the left of the slider, and the blade is to the right – if kickback happens, the operator is entirely out of the line of fire. Likewise, the operator's hands are pushing the slider, not near the blade. Since the work is moved with and/or fixed to the slider this eliminates entire classes of errors that lead to injury. The design difference is profound, akin to the coding philosophy of "make bad states unrepresentable".
I'd absolutely prefer a SawStop if I were using a cabinet or contractor saw again, but IMO a sliding table saw is intrinsically safer than a cabinet saw, even with excellent workholding discipline.
I am also all for the Consumer Product Safety Commission doing their fucking job and requiring this to be part of any table saw sold in the US, without paying SawStop any patent fees. This is a consumer safety issue; the exact kind of thing that the CPSC was created to manage, and they've done nothing to reduce or limit the number of appendages being cut off in saw accidents.
At the end of the day, it's really not hard to prevent table saw injuries. Use a riving knife, don't twist the wood and you'll pretty much never get a kickback. If something does go wrong you won't get injured if you keep your body out of the way. So don't stand directly behind the saw and use a push stick (I love my GRR-Ripper) so your fingers are never close to the blade. I'd guess the majority of woodworking injuries are due to people who know these rules but break them out of laziness or rushing. Table saws also aren't the only risk in a workshop. You can injure yourself just as easily on any other type of saw, jointer, planer, etc. It doesn't make sense for the CPSC to only require SawStop tech on table saws and putting it on every other tool would put the price of woodworking out of reach for most hobbyists.
From a quick Google search, 93% of table saw injuries are to the users' hands. The only actual deaths I could find were suicides. Yea it sucks to lose a finger but I'd argue that it's not the worse thing in the world. Pretty much everyone could still do their jobs minus one finger.
The one exception I would make is high school woodshop classes. Based on most teenagers lack of judgement, I think it does make sense to mandate that these woodshops only use saws with this technology. I'd be surprised if most school insurance policies don't already require it.
I used to work for a chainsaw manufacturer and we had devices on all saws without exception that would prevent injury in case of a kickback. Once this is part of all designs the cost is negligible.
I asked him one day about saw stop and his comment was surprising.
1. Good workshop behaviour is always safe.
2. The blade is all but destroyed in stopping so quickly. (A small price to pay, really)
3. He cited places that used saw stops had the highest levels of work place accidents... Which increased after having them installed... I think he mentioned that yes, no fingers lost though.
So, i think this device is wonderful, but can have nearly equally dire consequences, because it seems to breed poor safety.
isn't this just another way of saying "don't make mistakes"?
Not saying mistakes don't happen. I'm sure there are instances of people doing everything right and still getting injured. But as I explained I don't think it happens often enough and the injuries aren't serious enough to make the risk so unacceptable that we need to add $500 to the price of every new tablesaw.
Wood often has hidden stresses within its structure. An apparently straight length of wood can cup/bow/curl quite markedly when cut. So you can't always know if a particular rip cut will result in the wood binding between the fence and blade leading to kick back.
On the price difference point, I have a portable Dewalt table saw that cost about AUD$1100 with a stand. Saw Stop didn't have a portable version when I purchased. Now that they do have a portable version, it is about AUD$2000, roughly twice the price of similar models from other manufacturers (at least here in Australia). That's quite a price difference for hobbyists and home gamers who aren't deriving an income from the tool.
Edit: and it looks like Bosch has a cheaper system involving tech from airbag firing hardware that’s $50 per charge, that retracts the blade instead of catching it.
I take it you said that backwards on purpose though as sarcasm?
Applying braking technology to a blade doesn't seem like that novel of an idea compared to detecting a finger touching metal through change in electrical resistance.
That'd be a great way to stop any future safety innovation that may benefit many people.
SawStop isn't really a homeowner tool, but it is certainly within an accessible price range for enthusiasts, schools, and professionals.
[1] https://www.toolnut.com/power-tools/saws/table-saws.html?man...
That $1000 difference wouldn't even cover most insurance plan deductibles for one ER visit. Not to mention specialists, surgeons, reconstructive surgery, physical therapy, etc.
The European philosophy seems to be that the Saw Stop isn't worth it, because if you get in a situation where it kicks in, it means you've done something stupid like not using a riving knife and not using a crosscut sled or other pushing device.
I think also the fact that you don't get the system on other types of saws (band saw, mitre saw, circular saw, etc.) says something about the efficiacy.
No, I don't think it says that at all, and you should reconsider your statement. I think it's a matter of geometry more than anything else.
The technology works. People do stupid things all the time. Having a backup safety device is a good idea, not a poor one. Or would you argue that safety belts and fire extinguishers are also unnecessary for "responsible" people?
What is in question, is the ability for an explosive block to stop a blade in single-digit milliseconds, before it can travel far enough to cut the user.
On a spinning saw blade, firing an aluminum block into a spinning blade and dropping the assembly away from the user is a matter of geometry.
How would this work on a band saw? If you can come up with a way, I believe a very lucrative patent is in your future.
Same goes with the other saws you've mentioned.
The official reply from Bosch when people asked on their forum about bringing the Reaxx to Europe was
""" There are currently no plans to bring the Reaxx to the European market simply due to differences in health and safety regulations across the two continents. """
My reading of this is that as long as people in Europe follow local H&S regulations, this technology is redundant. And they're not going to sell tools with features that enable people to disregard H&S regs.
Instead, I'll argue something similar, but different: the laws should require some level of safety, but not require any specific implementation of the feature, as long as it's safe and dependable (per legalese specifications, no doubt). However, there are many other <i>equally important</i> safety features to think about, such as (the term escapes me at the moment) inrush-detecting limiters that keep the saw from blazing to life when you plug it in [1], or saw blade covers that are actually usable and don't impede work.
If you were to invent, build, and manufacture something life-changing, would you want the government to socialize it and not compensate you at all for it? Part of the problem with the SawStop was that the inventor wanted an inane amount of money for the license, so Bosch, who saw value in the feature, worked around them. Do something like mandate that all products of type X include exact part Y leads what you see in the defense industry- parts that aren't priced competitively, and might not be the best thing for the job. (Yes, I know there are holes in this analogy, and that building stuff costs money.)
[0]Link to legal fight between Bosch and SawStop: https://www.protoolreviews.com/news/sawstop-vs-bosch-reaxx-l... [1]AFAIK, the general mode of operation for these is to flip the switch to off when it loses power (like a GFCI, I would guess).
>requiring this to be part of any table saw sold in the US, without paying SawStop any patent fees
I don't think you are for SawStop or their invention. Sorry, you don't get to cheat someone out of their work just because it's a good idea. It's pretty much the exact opposite of that.
SawStop invented a thing. Does that mean nobody else can ever produce a similar thing?
Ford created the first mass-production automobile. Did that stop other companies from developing their own cars with their own internal-combustion engine? I don't think so.
Where do you draw the line on what is patentable and what is not? If I have designed a new pharmaceutical compound and it is patented, does that mean other companies can not synthesize their own version of the same compound and sell it under a different brand name? I suppose if we apply this logic to mechanical devices, you pretty much kill all competition for the life of the patent.
No. SawStop patents (there are many) begin expiring in 2021.
> Ford created the first mass-production automobile. Did that stop other companies from developing their own cars with their own internal-combustion engine?
As you say, Ford wasn't first to the ICE car game. They did have patents on the Model-T, though.
>Where do you draw the line on what is patentable and what is not?
https://www.legalzoom.com/knowledge/patent/topic/what-is-pat...
> If I have designed a new pharmaceutical compound and it is patented, does that mean other companies can not synthesize their own version of the same compound and sell it under a different brand name?
That is correct.
> I suppose if we apply this logic to mechanical devices, you pretty much kill all competition for the life of the patent.
This logic does apply to mechanical devices, but it doesn't "kill all competition" because companies can design around existing patents. If you can find another way to achieve the same effect that's not covered by the patent, then you're fine. In practice, this happens all the time.
I'm not against SawStop saws, and in fact I own one, but I would not feel any danger using any other type of table saw in good working condition. Understanding how the machine works and taking the proper safety precautions is much more important to your overall safety than something like SawStop technology.
A trauma doctor invented a new helmet for motorcyclists. Reduces neck injuries. Couldn't get any mfgs to bite. So he started his own company.
Gotta love the innovator's dilemma. (The opportunities are insurmountable.)
A useful contextualization for how powerful most stationary power tools are (table saw, but also jointer, planer, chop saw, shaper, and, yes, band saws too) is that they're usually rated for continuous output of several horsepower. Go do an image search of people getting kicked and or thrown by horses. Now think about how much that must hurt.
Now, remember each of those machines is as powerful as one or more horses, and has a commensurate ability to injure you[0].
Can't stick around to discuss this now, but I'll check back this evening.
[0] Yes, I know the history of the horsepower and exactly how much power a horse develops is imprecise. For getting a rough idea how much you can get hurt, it's immaterial.
Format table saws used in most carpenters shops here have 5-7.5 kW motors (7.5 kW are ~10 HP). Impressive power. Though format saws are far safer by design than regular table saws (and better for both your back, and accuracy, too).
That being said kickback is almost always caused by making a cut that simply can't be made safely on a table saw. With suitably sized work pieces the next major concern is binding; a riving knife helps with this but naturally cannot prevent it -- it just gives you more time to shut the saw off. (Larger workpieces are also somewhat -- not much -- less problematic when caught on the blade, because they won't fly as fast or far as a small, light workpiece).
I think part of the appeal of a table saw for woodworkers here is that if you can set up a jig, you can do a lot of pieces with good repeatability. I cut bridle joints to make seat frames yesterday, for instance, and once I set up the jig, I could cut them quickly and accurately. Ditto cutting tenon cheeks.
This is definitely one of the sketchier things you can do with a table saw, in large part because the workpiece is standing on end (supported by the jig, of course), but if you cock it out of vertical, you've set up a situation where kickback is quite likely. This is something I'd love to hear about a safer alternative.
As it happens, I have an old Unisaw, and I have an original sliding table for it. I would really like to see what I can do with that above and beyond the obvious.
Thanks!
Jigs are normally mounted to the sliding table (which has T-slots for this), which pretty much constrains both jig and workpiece to a single degree of freedom. (And if you clamp the workpiece to the jig you can guide the cut with one hand on the sliding table and still have another hand free to support e.g. a long workpiece that's mounted vertically -- and both hands stay well clear of the saw blade).
Basic operation would be e.g.
- having a panel with one straight edge, cutting a panel of given dimensions with square and straight edges out of it. Straight edge goes against the cross-cut fence that's mounted on the sliding table, first cut, turn 90° and use stop on the cross-cut fence (they usually have two independent stops) to cut it to width, turn 90°, cut to height.
- Rough sawn lumber with live edge, clamp it to the table, trim live edge off, use rip fence to trim the other side off.
- Unlike a miter gauge / cross-cut slider on a normal table saw, the sliding table can be used together with the rip fence safely. This makes it very easy and safe to rip narrow strips from a wide panel or board. This also makes it easy to e.g. cross-cut square-ish things off a board or panel, something which is pretty much impossible to do safely on a normal table saw. The rip fence on an F45 goes to well over a meter, so if you have many parts with the same length this is a real time saver.
- There are very accurate miter gauges that use fixed stops to mount to the sliding table (e.g. Altendorf Duplex). These allow to cut "into" the miter in both directions with basically perfect accuracy + repeatability (even when removing the jig from the table, as long as you don't touch the stops on it, it will cut the same miter when re-mounted). All miters I have ever made on the Duplex came out perfect, except a few that I screwed up during glue up.
- For edge mitering using the swivel-function of the blade works very nicely because even older models have digital readouts which are accurate enough that you can set them to 45.0° and get a perfect joint. Some never saws can swivel the blade in both directions (+45° and -45°). Swivel and cut depth are adjusted by foot-pedal (which I think is pneumatic) or electrically.
- Some rip fences can go to a few centimeters negative, zero included, which means you can use the saw as a sort of big flush cutter.
Scales are adjustable and use magnifying readouts, (mirror) vernier scales or are digital. When adjusted correctly, they're very accurate and repeatable. Rip fence on an Altendorf has a fine adjustment that works after clamping, so no measurement change due to tightening the clamping.
Overall it's just very nice to work with because you don't have to move the workpiece around by yourself, and when using the rip fence you're always standing a good bit off to the side.
Felder: https://youtu.be/LVYUss6pJqQ
Altendorf: https://youtu.be/L8JR_fD-dMI
I’m sure there are innumerable options and configurations but these gave me a good idea of basic operations
Table saw kickback experiments https://www.youtube.com/watch?v=xFkHmgRIkOI
Effects of table saw misalignment, and kickback https://www.youtube.com/watch?v=Fbca0Km8Q5E
https://www.youtube.com/watch?v=kIfuViyki0Q
It's very easy for anyone to drop his guard which leads to injuries. Since a lot of people admire his skills, he provided a great public service to the community by showing how his small moment of carelessness lead to an accident.
He obviously has a very deep understanding of his tools (since he built most of them) and where the danger lies, but I would say that he also intentionally accepts a little extra risk with cuts to save time. In his specific case I think he does have enough experience to make the trade-off safely, but if you were a new woodworker I would not learn any safety techniques from his videos.
I love that channel.
[0] - https://www.youtube.com/watch?v=7Yo6ALeIfF4&list=PLPCaXyAa7W...
He tells that story when he thinks people aren't having enough respect for power tools. He could have been much more severely injured. If he hadn't been wearing safety glasses he definitely would have lost his eye and could have had brain damage as well.
Human strength and reaction times are so insignificant compared to these machines. It's purely an illusion that we are in control of them, and there's no reason not to use all of the safety measures and precautions available to us.
For better or worse, I'm unable to forget a picture of the victim of a lathe accident.
The Grr-ripper is what I use the least, but it is one of the options that is really irreplaceable. For example if I have a long thin piece of wood (say 2' long x 2" wide x 0.25" thick), and I want to rip it into 0.5" strips, then the only way to safely make this cut is with something like the Grr-ripper. It is the only way to get grip on a thin piece of material and allow me to put pressure in the appropriate places (downward, towards the fence and through the saw).
But keep in mind in this specific example that the stock is not very wide. If you have a 6" piece of stock and are cutting off 0.5" strips, then by far the safer way to do it is to keep the bulk of the material between the fence and the blade and have the off-cut be the thin strip (and there are a variety of ways to setup your saws to do this cut repeatably). In this example the wood is also very thin, which is important. If the wood is thicker then the danger of ripping on the table saws increases, because there is more surface area between the blade and the wood, and at some point I'll just go over the bandsaw, rip things to rough size and then clean them up on the drum sander.
I'm also a huge fan of the grr-ripper rip block for the jointer. I use it all the time for thinner stock where I don't feel there is enough distance between my hands and the blades.
(very amateur woodworker who makes repeated cuts like that with the bulk of the wood on the other side of the blade so he doesn't have to move the fence each time)
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Let's say I pick up some 2x4 and want to get rid of the round edges so it's pretty darn square. Are you suggesting to run an 8 foot 2x4 through a band saw to remove the 1/4" edges? First you need a damn good band saw to even attempt this.. you wouldn't have any decently long fence really. And even if you set this up all perfect, there's no way it's going to be even close to a straight cut.
Handheld jig like you saw could kind of do it, but my god that would be an awful cut even with a straight guide.
Ripping boards is basically impossible to do well without a table saw.
I agree a lot of other stuff can be sort of done with alternatives, but no where near the speed/accuracy. And if you do any woodworking, you know how much that matters.. if you don't get good cuts you end up taking forever trying to fix everything.
Anyway.. I hate using table saws, and do try to avoid it. But there are some tasks where it would be ridiculous to not use one.
IIUC, fixing severed nerves in the spinal cord is beyond the state of the art in medicine.
So when someone goes to the ER with a cut-off finger, how is it possible for the finger to be reattached, and for the proper nerve connections to be re-established?
The peripheral nervous system can regrow nerve tissue but only if it has an intact pathway. So when they sew on a finger, if they can repair the myelin sheath, new nerves will grow down the old conduit at a rate of about an inch a month.
So they sew your finger on and you have to wait a few weeks to see if you're going to get any feeling back. That waiting would drive me nuts.
When he went to edit the footage, he discovered to his horror that when the board kicked, it nearly sucked his fingers into the blade. Missed by less than an inch. The final edit ended up being mostly a message of "learn from my mistakes". Basically I learned that there's never a good time to have a kickback, even if you're trying to make an educational video.
Yes this might be the one. Somehow on mobile I missed the big scare banner at the beginning.
I don't think any of us realized at the time just how close I was to injury.
The usual reaction is to stare dumbly at your hands, and then stock up on push sticks, push pads, and work holding jigs ;-).
I probably avoided a broken rib thanks to having all the safety features of the saw on. Beam ended up jammed into the guard instead of jammed into my chest. So many people leave those things off because they're inconvenient. Glad I didn't.
The kickback happened because the blade was so shallow. As I pushed the board into the blade, it rode up on top of the blade. The answer is more downward pressure, but I was using two push sticks to guide it through and didn't have the leverage to provide that pressure. Luckily, I was in a completely stable position and at no time were my hands anywhere near the blade, but it was still pretty scary.
There is also this music remix version that I kinda like: https://www.youtube.com/watch?v=LfIJtR6R1jY
You always see those pictures of a hurricane taking a piece of grass and embedding it into a telephone pole, well a table saw can take a 2x4 and put it through just about anything. Crazy powerful tools.
Your average gasoline gallon has 33kW worth of energy in it, which can drive your car for about 35 miles or around 1kW / mile.
Look at your average table saw running at 600W of consumption and consider that piece of hardware is using up enough power to move your 3000 pound car a little over half a mile.
kW are a unit of power (energy/time, 1 W = 1 Joule/s), which is not relevant to measure energy content (for a gallon of gas). You'd want plain Joules for that.
Fellow product geeks might enjoy the design tradeoffs that different countries made, and injury statistics: http://sawsafely.org/#understand-design-decisions-&-trade-of...
Like, I worked with people who climb industrial chimneys professionally(for inspection, cleaning, etc). Now, in the UK the safety code requires that they have to clip in to the ladder they are climbing with a safety harness every 2 steps. So take two steps, attach one clip to the step above you, remove the clip from the step around your waist, repeat until you are at the top. Now - this might be a safety procedure, but literally no one follows it - simply because if you wanted to do that, it would take you 30 minutes to climb a 100m tall chimney. And these guys have absolutely zero fear of heights so for them cliping in is stupid anyway.
I imagine the same logic applies here - sure I could mount the blade guard....or just cut the plank carefully like I did 1000 times before already...."what am I, an idiot?".
A lot of safety procedures and best practices diverge wildly from those in other industries. I get the impression it's probably the same way with chimneys in the UK, given that industry's long history. [1]
In arboriculture, the following weird things are acceptable(-ish, depending on the country):
- The climber is often supported by a single non-redundant rope, unlike rope access in other fields where two ropes are required.
- "Riding the ball", or using a crane to hoist a human load, is done in exceptional circumstances.
- Some critical PPE gear is often hand-made, it's very common for climbers to splice their own ropes.
- Even the most die-hard chainsaw-safety advocates will grudgingly acknowledge that sometimes situations call for one-handed use.
Some of these industry practices are in direct-conflict with more broad OSHA and/or EN safety standards. It isn't that the industry disregards safety - most climbers and crews I know are very safety conscious. Rather, the situations are different enough that the risk-mitigation calculus arrives at different answers.
Where a ladder climber may be not-always attached to the ladder, in the tree-care industry, that's utterly unacceptable.
[1] eg, one of the many Fred Dibnah videos on YouTube https://www.youtube.com/watch?v=3R3-YwDZrzg
But this seems stupid. Anyone with hands will realize that sliding your gripped palm around and up a round tube in a neutral position (that is, with your palms facing each other, not facing down) feels more secure then hand-over-hand on the steps, which don't give good grip anyway because the lip of the step faces down, not up.
Examples:
http://www.ippis.it/negozio/scale-in-alluminio/scala-in-allu...
https://www.ediliamo.com/scala-professionale-con-parapetto-f...
Makes climbing really easy and safe. Technically you don't even need to use your hands for anything .
I do not do work-at-height, but my (unoriginal) proposal for a simple solution is to run a steel cable from bottom to top, anchored at both ends. This is cheap and low maintenance. Then a worker can bring their own cable-grabbing fall arrestor with a progressive-tear lanyard. Attach yourself to the cable at one end of the ladder, and climb up/down as you would normally until you reach the other end.
If that buzz saw didn't kill me, I'm not fiddling with that stupid safety guard on the table saw/lawn mower/high-amperage device; I've got shit to do, I know what I'm doing.
(In reality, I personally use every safety feature of every cutty/stabby/choppy powered device I own. I'm not getting any smarter or attentive in my old age.)
It's absolutely insane, and what's worse, the person posting it considers this a positive advertisement of their company.
PTO Guards, ROPS, 4WD(almost no tractors have brakes on the front wheels, so running a loader downhill can be really dangerous). All things I'm incredibly thankful for.
The answer is twofold: number one is 'oh, these instructions are overly cautious, my expertise trumps them', and that is compounded by the fallacy of 'well, I've done it and seen it done for x years this way and have never had a problem'.
no safety shield on his face
no gloves
baggy sweat pants
not even a shop apron
its just ONE GUY in a...garage? no safety spotter or anything. Its sheer luck that this guy didnt end up live streaming a suicide.
What thintz12 is also not considering is the blade itself is likely carbide tipped. the tips are hard, so if you crash the tool into the steel frame of the workbench, those bits can fly off like a bullet. a kickback that crashes a tool or jams the machine will also trip the breaker youre plugged into. If that breaker controls your garage door, and you're badly injured, you will not be able to make a simple and quick exit for help.
Wearing gloves when you are working with spinning things (table saw, lathe, etc) is a huge no-no. The glove may initially protect your hand, but as the blade shreds it, it will get tangled up, and will pull your hand into the blade.
So either the gloves are pointless, and your original critique was wrong, or gloves are worthwhile and could get pulled into the machine. Pick one position or the other.
It was a cut-resistant glove, made from kevlar with a rubberized palm. Lesson learned that day.
But obviously, do whatever you want, YMMV.
There's no good reason to wear gloves when woodworking with machines.
After the fact he realized the magnitude of how dumb this demo was.
Kick-backs would never even have been on my radar, even though I’m seeing myself as a careful person, if it wasn’t for YouTube and people like him taking their time to educate the rest of us.