I used to have multiple clamps around the controller, message bus, the firmware and also a physical barrier, and yet would not feel safe with my fingers or person around moving parts.
I'm just glad that ultimately he was the only one who faced physical consequences for his poor choices. And thankful that the consequences weren't that bad at the end of the day; a broken arm is way better than a cracked open skull.
Is he next to the malfunctioning robot?
In other words, some person did something very stupid, while thinking he is clever.
That made me actually lol.
I would assume he'd be the poster-child for following safety protocols after that. But I'm still learning a lot about human nature.
It’s weird how even ordinary things can be dangerously loud.
There was an absolutely almighty BANG, of the 'an explosion has just occurred' variety that made me very glad I wasn't actually cutting metal at that precise point in time. His g-code had an off-by-one error (I think) and it had dutifully picked up a ~20 cm HUGE flycutter, spun it at the speed of of a ~5 mm bull nose cutter, and driven it directly down into a piece of aluminium. The flycutter had broken and effectively welded itself to the aluminium, which had sheared down the middle, spun out, and hit the protective guards that completely encompass the machine. The person driving it (either a postdoc or graduate student) was maybe 40 cm away and saw this ~2 kg piece of metal bounce off a thick reinforced poylcarbonate guard directly at the level of his head.
Safety equipment saves lives.
Or a dental x-ray machine has the final "run" button in the hallway so the nurse taking x-rays must go there to do it, so they don't get repeated exposure.
Sadly the inventor couldn't convince the tablesaw manufacturers to use his invention for cost and/or liability reasons so he had to make his own. Their tablesaws themselves are relatively expensive but cost per accident is $100 for the charge plus whatever the blade costs, so basically $200 to prevent serious injury or death.
So on a worksite if you are using lumber that hasn't had adequate time to dry the saw stop would trip even without any limbs being in danger.
Each time it would destroy itself, you would have to take the saw apart and change it which would cause a work stoppage.
What irks me the most is that the SawStop owner tried to create legislation that would have required companies to use his product.
The lobbying is off putting, yes, but at least his greedy self-interest would do some actual good instead of extracting evermore capital from everyone. Powertools inhabit this uncanny valley of dangerous equipment where they're cheap and accessible enough to the average joe (compared to CNC machining centers or forklifts or whatever) yet powerful enough to do some real damage. My understanding is that the primary reason the major manufacturers didn't want the SawStop wasn't cost but the fear that it would expose them to more liability by making the tools seem less dangerous. I really wish it achieves mass adoption so that the price drops even further.
The problem with causing $300 of destruction and lost work time vs possibly saving a limb is there's no fine woodworking operation or framing carpentry operation that requires a table saw. Technically if you feel unsafe working with a table saw you can do absolutely everything very slowly and tediously with a router or router table or bandsaw, or manual tools like a chisel and hammer. Anyone concerned about safety doesn't use a saw stop, they use an entirely different technology than a table saw. If you make a table saw too safe or too expensive to actually use, people will simply use something else. The death toll may or may not be lower...
From a marketing perspective, the people most likely to buy a saw stop because they're scared of table saws will save a lot of money by not buying either sawstop or table saw, and they'll cut dado slots using a hand held router (more dangerous in a different way) or break down plywood using a tracksaw (unholy expensive and many crushed foot injuries) or cut beveled edges on a router table or zillions of alternatives. Meanwhile the people who don't care about safety because they're not drinking on the job or they actually use the substantial amount of safety gear that makes a table saw perfectly safe OR they only do operations on the table saw that are inherently safe by nature (as opposed to relatively low risk operations, and some very high risk operations that people do anyway), will continue to save a lot of money by the combo of not being dumb and not buying sawstop. Finally the real dumb woodworkers who get drunk and get hurt or simply don't care, will continue to not care and not buy sawstop and will not live too much longer in a world either with sawstop or without table saws anyway, so its not like the world will net improve, the Darwin award winners will continue to win Darwin awards. So sawstop is a VERY hard sell.
A similar problem is well manufactured table saws are safer than homemade table saws. The concept of "put a round blade on a motor" is too simple to legislate out of existence. So making table saws illegal wouldn't eliminate table saws it would just mean the homemade ones will make table saws, on average, more dangerous.
Arguably, radial arm saws are more dangerous than table saws and "the marketplace" effectively eliminated those decades ago, so its not like the marketplace dislikes safety or whatever.
> Meanwhile the people who don't care about safety because
> they're [never doing unsafe things]
For table saws, having a sawstop helps prevent situations that you don't have fill control over from having bad consequences. Of course you'd still use all the same safety measures you normally would without one.
There's another class of accident involving equipment. Some people do not store firearms with trigger locks or unloaded in safes or whatever. Likewise there's an analogy with table saws where I don't rip small boards without a nice featherboard, riving knife, and some really nice plastic pushsticks. If as you claim my mind drifted, this time by use of tools it would still be physically impossible to hurt myself.
There is a class of inherently dangerous operations where no safety tools exist but the table saw is so versatile and flexible people can successfully do the operation... most of the time. My point is instead of spending more money to build a "better" tablesaw to do something dumb, simply invest the money in a COTS bandsaw or track saw or jigsaw hole cutting jig or chainsaw or planer or whatever crazy risky thing there's a better, faster, safer tool. You can do dangerous things with a table saw but there's always a better safer faster way to do it with a different tool. Taking away money by making the required table saw more expensive just means the woodworker will not be able to afford the superior even safer tool for the job.
All the evidence I've found is super cloudy, but early reports indicated Bosch's variant predated SawStop's release.
Luckily SawStop's patents expire in a few years so hopefully we'll see other safety mechanisms similar to SawStop without the downsides and greed.
[1] https://www.youtube.com/watch?v=NV6Jhw0hhBI (at ~3 min)
Not everybody's cup of tea, but our ability to be 'present' is highly variable, both person-to-person, and one person over time. I'm a somewhat daydreamy sort of person, so I work to bring focus when I'm using power tools. As a hobbyist I walk out of my shop when I get tired, emotional, or otherwise distracted, but that's not an option for everyone.
Is there any proof of this? From my understanding, that's a myth. Demonstrated here at about 3:00 https://www.youtube.com/watch?v=NV6Jhw0hhBI
It's also saved a few legit fingers, so it's still a net win, but you've got to have pretty deep pockets to cover all the false trips.
You’d be surprised at the number of materials you might want to cut on a table saw that are unexpectedly conductive.
Every tablesaw injury I remember hearing about involved the operator failing to follow some of those guidelines.
You're supposed to turn off the circuit breaker and lock it with your own personal lock that only you have the key to. That way no one can turn it on even if they wanted to.
I've heard no one, under any circumstances is allowed to take the lock off. If the person leaves after their shift and forgets to take it off for example, they have to come back in the middle of the night so to speak and take it off.
It's not only electricity that needs to be isolated and locked out. A lot of machines use air pressure to operate moving parts, so in that case you'd have to isolate all electrical sources as well as the air. The machines I usually mess with require 2 locks. Some of the machines I've seen can require 6 or more locks to be fully locked out and safe to work on.
A typical maintenance period might require 100 or so separate tagouts, each of which could require anywhere from one to dozens of tags. Each duty watch was required to show up early enough to go through the entire tagout book and at least know the gist of what was in progress.
Finding a loose tag was an automatic all hands all work stoppage, until it was tracked down and resolved. No questions, even if your work was in a different compartment, or had no logical connection to what he tag was for.
Each new tagout request had to be signed off on by at least three people, sometimes all the way up to the captain and not just a foreman or supervisor but one or more shop heads.
Seawater system tagouts on a floating sub were serious business.
Of course, the weakness of a system like this being if middle management is demanding unachievable timelines and/or people in the shop are willing to cut corners, someone can leave a box of heavy stuff on the pressure pad to "save time." Absolutely right that all these systems need to be resilient to operator tiredness etc
What does this mean?
It was close to lunch, so I kept eating.
The finale was a jar of mayo spilled into the guts of a 50k server. Best mayo I ever had.
Anyway, try out a Point Chaud. Same overflowing sandwiches.
I once bought one, I walked out the shop and 45 meters later the sandwich literally went through the paper bag and fell down on the ground.
Back when I was doing some hands-on practical training in electric engineering school, we had to design a control circuit on some breadboard, the kind that in high school would lit a couple of leds, and maybe make a light fade, but here it was driving a big-ass train engine boxed in a 1.5m x 1.5m x 3m steel cage, right next to the bench where we pieced the control device together, barely arms length away.
While conceptually the same, "theory" vs "practice" and "command" vs "power" suddenly takes a whole new meaning where you're suddenly pushing several orders of magnitude more power than a puny 9V battery could. The buzzing of a hundred amps ready to flow inches away was chillingly ominous. You get a strange urge to triple check, quad check even, design and calculations before flicking the switch.
As we all successfully started up our bench, the rumbling of a dozen of these bare protomachines revving up in a hangar was eerie. The thought of them sucking in such an amount of overall power from the grid dizzying. I rarely get cold-sweat and goose bumps, but this was one of these days.
The motors were quite powerful and there were a few close calls which really made you think.
It used to twitch violently as it was calibrating on initializing. Once, it reset and did that while testing. Luckily the person holding it managed to get his hands out of the handles on time.
Another tim the tip of one instrument had broken off and during initialization there was an error in the force applied in the direction along the shaft. It flew out like a rocket.
Tesla Autopilot developers should read this.
Back in 2002, I was getting a package with a brand new Pocket PC (smartphone without the phone, running Windows). And I really wanted to know when it was delivered, but the UPS guy would regularly leave packages on the porch without ringing the bell or anything.
This was before you could get delivery alerts or anything like that. But I had a spare laptop with an integrated webcam (wow!), and I'd figured out how to make it run actions on motion detection.
My plan was to point the laptop at the door, and eject the CD drive when it detected motion. The tray of the drive would push a water bottle off the table. That would land on a seesaw, which would launch a deck of cards in a hard plastic case at the door and make a very loud noise.
It's unclear why I couldn't just play a really sound on the speakers instead. Anyway, I tested the program by standing in front of the laptop and waving my hand.
It worked perfectly! The CD tray ejected, and I watched as the water bottle slowly rolled off the table. It dropped onto the seesaw...... and instantly launched a hard plastic deck at my face and got me right between the eyes.
Never again have I been in so much pain and also so excited about my code working perfectly at the exact same time.
Also I like that even after you came up with "knock something off the table" you felt you needed a seesaw catapult thing and didn't just knock something off that could make the actual sound like a cake tin or bell or something.
It totally doesn't make any sense! I think I might have been fascinated with the idea of Rube Goldberg machines or something at the time. Or maybe I thought I could build a "security system" with it? Also it was summer and I was a bored teenager.
One key observation, though, when working with code is that the machine becomes so close to predictable that it's more dangerous than if it were unpredictable. A cordless handheld drill is hardly a tool that most people would call 'hazardous'. You turn the trigger, the thing rotates, grab the chuck and you can likely stall it. But that much energy in something driven by code is extremely dangerous, it's waiting for any of who knows how many conditions to take off, a common one is that putting your hands in/on something that seems to be not moving can 'make' a sensor and the machine will take off.
There are definitely two kinds of safety domains, one applies to manually operated tools where the operator of, say, a knife is responsible for their own safety - if they cut themselves, they're at fault, not the knifemaker. There's another kind of safety engineering where if the machine takes off 'by itself' while an operator is in the way it's the machine designer's fault for not stopping that from happening, the operator can't be expected to know what's going on.
The latter should become more common as computers continue to permeate everything we use - that cordless drill is no longer controlled by the operator with a trigger switch that connects power to a DC motor, it's a brushless motor driver with an analog input sensing the position of the trigger and the EMF of the motor, and the charge state of the batteries, and who knows what else. Bump a sensor and it might take off, you don't know why it does what it does.
I'll continue to make my automated cells as safe as I can, but don't trust code that's not so simple you can be confident of how it works.
A friend needed a valve cover gasket changed on his Honda, and his wife needed to use the car for her Uber runs that night. He came over and instead of our usual hand tools I put a socket adapter on my 20V drill to speed up disassembly. I handed the drill to him and told him "start on the lowest torque setting, and move up in small steps."
I turned around to grab more tools from the toolbox. A minute later, I heard a loud noise. I turned to see the car's windshield cracked and a shocked look on my friend's face.
My friend was used to his renter's power drill. He hadn't anticipated how much torque a modern contractor's drill outputs and set the torque to the maximum setting. On the third valve cover bolt, the drill had caught on the bolt head and spun my friend around, smashing the battery into the windshield.
There's a piece of paper taped to me toolbox called "List of things <friend's name> may not attempt unsupervised." It gained a couple of entries that day...
You should image-search the term "radial drill" sometime. ;)
$21: https://www.amazon.com/Irwin-Tools-Drill-Press-226340/dp/B00...
$25: https://www.harborfreight.com/4-inch-jaw-capacity-drill-pres...
You don't need a high-dollar Kurt milling vise for a drill press, and you only need to constrain the part in one degree of freedom (rotation about Z axis). Just put a single fastener in your table and drop the slots in that vise over it. Gravity and quill pressure hold it in Z, the table holds it flat against rotation about X and Y, and you want it to have the ability to slide a bit in X and Y to let the drill find the center of your punch/pilot hole. If the drill catches, the torque will push against the stud and it can't move.
A lower power (e.g. 300Nm max) battery driver is great for when you have to undo lots of lower sized bolts, while it would be a little bit underpowered for wheel nuts or motorcycle fork retaining bolts.
They're supposed to tentioned correctly with a torque wrench, usually between about 110 and 120Nm.
Edit to add a reference, just random from a search: https://www.barum-tyres.com/car/expert-advice/safety-driving...
And for that purpose, it does seem appropriate.
However my point still stands, somewhat: if 300Nm is insufficient to undo your wheelnuts, they're way too tight.
Ducati single-sided swingarm nuts can be similar, but I have not yet owned a Ducati.
That is often the difference between home and tradesman tools. A tradesman can reasonably be expected to handle a bit more responsibility from their tools than the home handyman.
But that same drill might be asked to bore a large hole in a piece of wood, and the user would anticipate the amount of leverage they need to control it. Two hands, arms close to body, etc.
Relevant old article: http://www.team.net/mjb/hawg.html
For a continuous drilling operation the torque is totally fine, the problem is abrupt changes in torque because of something catching. On drills without this feature that's what the torque limiting clutch is for.
We actually had an older drill with the mechanical clutch with a stripped high gear that we kept around for driving screws instead of tossing because the new one was so bad.
She mentioned that this had happened to a v high end CNC machine the cutting tool after a power cut went straight to the home position very $$$$$$$
At my place we had a computer controlled wave tank and as the guy I shared an office with said you could program the ram to go full travel in zero time which would have flooded the lab.
One day I had some friends over for a glass of wine, and wanted to show off my creation. I invited them into my "lab" and placed my wine glass down on the desk so I could type a few commands with both hands.
My rudimentary software had some motion smoothing once it was up and running, but upon initialization, if the arm was significantly displaced from where it had been when it was turned off, the PWM board would instruct the motor to immediately "be" in a position that required the arm to travel clear across the desk in effectively as little time as possible.
In this case, where it had been previously happened to be where my wine glass was now, and the flimsy aluminum at high speed was enough to shear the stem from the glass and explode the bulb. Luckily the wine didn't get in any sensitive electronics, but I learned a valuable lesson about the difference between messing around with hardware vs software.