Have you ever hurt yourself from your own code? • Hacker News Board

Re: Have you ever hurt yourself from your own code?

#401

Post by yetihehe » Fri, May 28, 2021, 10:59 AM UTC

lcuff wrote: post #313

ArchOversight wrote: post #294

Earlier quoted context omitted.

The biggest problem with the saw stop is that wood when it is even slightly moist can set it off. 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 cr…

Current saw stop units do have an over-ride switch so that if you know you're going to cut questionable wood, you can disable the safety mechanism for a series of cuts. (The safety mechanism comes back on if you power the table saw off, then back on.) But of course you don't know advance for sure if the piece of wood in hand will trigger the safety mechanism or not. Not everybody's cup of tea, but our ability to be '…

"Check mode" with stopped saw and light/buzzer instead of brake would be pretty good for such cases (unless wood has some internal moisture).

Re: Have you ever hurt yourself from your own code?

#402

Post by Agentlien » Fri, May 28, 2021, 11:12 AM UTC

ghostpepper wrote: post #5

A few years ago, I ordered the cheapest six-axis robotic arm from ebay for about $100 that came with basically no software or motor-driver boards, so I did it all from scratch with a PCA9685 board, a basic kernel driver and some very hacky scripts from user space. 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…

At my first job we once developed our own controllers with haptic feedback for our surgical training simulation. It was amazing how realistic the feel was.

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.

Re: Have you ever hurt yourself from your own code?

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Post by jdiez17 » Fri, May 28, 2021, 11:54 AM UTC

Doxin wrote: post #381

monocasa wrote: post #290

Earlier quoted context omitted.

Used to work in robotics. The QA folk were obviously very much sticklers for the full process of enabling the hardware interlocks before getting near the moving bits. One time a manager got mad at them for taking so long going through the full interlock process while repeating a failure mode. He therefore went up to the machine saying "look, it failed so it's stopped, that's how the code works!" At that point our bet…

I don't work in robotics so I might be entirely off-base here, but surely the interlock process would consist of hitting an E-stop somewhere? What was this process that took long enough for said manager to get annoyed with?

You usually only hit the E-stop when the robot is moving in a way that could be dangerous. Safety interlocks are intended to minimize the probability of such a dangerous situation. The robot won't move unless all of the interlocks are outputting a "go ahead" signal. The most common interlock is a (switch/laser/hall effect sensor/whatever) that detects the door to the robot cell is closed.

Re: Have you ever hurt yourself from your own code?

#404

Post by Digit-Al » Fri, May 28, 2021, 12:14 PM UTC

monocasa wrote: post #346

neilv wrote: post #316

Earlier quoted context omitted.

I hope that the arm healed well, and that, after the painful demonstration, everyone in the organization was fully onboard with workplace safety protocol.

Yeah, the arm healed great, and whole situation (plus the subsequent "N Days Since a Limb Mangled" sign) contributed greatly to the manager's humility and respect for safety.

> plus the subsequent "N Days Since a Limb Mangled" sign

That made me actually lol.

Re: Have you ever hurt yourself from your own code?

#405

Post by VLM » Fri, May 28, 2021, 12:20 PM UTC

gknoy wrote: post #306

VLM wrote: post #304

Earlier quoted context omitted.

Thankfully the patents are starting to expire in 2024. Nothing holds pack progress quite like the patent system. 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 wit…

> Meanwhile the people who don't care about safety because > they're [never doing unsafe things] This sounds an awful lot like suggesting that skilled users of firearms don't care at all about safety because no one's going to deliberately do stupid stuff. It seems farcical to me. Just as with firearm safety rules, they're there to protect people from the rare moments when we are inadvertently NOT careful. History has…

Most firearms accidents happen during normal operations like carrying, cleaning, disassembly, and so on. In comparison table saws are extremely versatile and can do many operations some of which categorically prevent entire classes of accidents. For example I have a commercially made box cutting jig with various shields and guards and its not physically possible to stick my fingers in the blade during operation. If as you claim my mind drifted and I did stupid stuff, by physical design of the operation its impossible to hurt myself.

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.

Re: Have you ever hurt yourself from your own code?

#406

Post by adrianN » Fri, May 28, 2021, 12:23 PM UTC

ecpottinger wrote: post #329

akiselev wrote: post #288

Earlier quoted context omitted.

Another awesome safety system is the SawStop which uses the conductivity of skin to monitor for contact against the blade in a tablesaw. If it detects contact a small explosive charge goes off, instantly sending a block of aluminum into the path of the blade, stopping it dead. Even a serious accident like leaning with an elbow against a moving blade is likely to result in little more than the scratch from hitting a s…

Is there anyway to do it magnetically using inducted currents? I doubt you can stop the saw that way, but you should be able slow the blade down so it does not do as much damage.

A tablesaw goes through a finger as if it is nothing. Fingers can move at speeds of dozens of centimeters per second. So anything that takes longer a dozen microseconds to stop the blade will not be good enough to let you keep your finger.

Re: Have you ever hurt yourself from your own code?

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Post by hnbad » Fri, May 28, 2021, 12:47 PM UTC

toolslive wrote: post #275

cedricd wrote: post #270

Earlier quoted context omitted.

In other words: please go home and I'll call you. 'Head on home' is a real expression. Similar ones are 'head over there', 'head to ...', all of which just mean 'go to'.

is that a pars pro toto?

No, "head" is a verb in this case. Related to "heading" (i.e. what direction a vehicle is pointed at while moving), I think, rather than the body part.

I can't find the etymology beyond words meaning the body part or "primary"/"main". There's no direct equivalent in German for example despite the shared etymology for the other meanings.

I would guess that it is related to the body part in a figurative sense in the same was as "face" (i.e. turn your body in a specific direction) though I have no idea how "put your head there" would come to me "go there". I wonder if this was before or after "heading" became a thing for ships (which generally move in the direction they "face", so the "heading", i.e. how the "nose" is aligned, could go on to become a verb).

EDIT: I'm not sure it's pars pro toto because I'm not sure it directly refers to the "head" in the sense of the body part rather than the "heading" which is not directly related to the actual body part when talking about vehicles like ships.

Re: Have you ever hurt yourself from your own code?

#408

Post by hnbad » Fri, May 28, 2021, 12:48 PM UTC

FabHK wrote: post #366

toolslive wrote: post #275

Earlier quoted context omitted.

is that a pars pro toto?

No. It's not "take your head home", with your head (a noun) being the part standing in for the whole, namely you. Rather, "to head" is a verb that means (among other things) "to move in a specific direction". For example, an aircraft could be heading north.

Isn't "take your head home" pars pro toto given that it means "take yourself home" with the head (pars) standing in for (pro) the person (toto)?

Re: Have you ever hurt yourself from your own code?

#409

Post by azalemeth » Fri, May 28, 2021, 12:55 PM UTC

AlotOfReading wrote: post #59

isatty wrote: post #35

Earlier quoted context omitted.

I used to do robotics, I can tell you that the fact that it was the cheapest or the most hacky does not matter in the least. Everything can and will go wrong, even the priciest and well documented part. 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.

Yep. When I have to work with robots, it's from a distance and with as much safety equipment as possible. I've seen too many physical, hardware, and software failures to risk anything I care about. Hearing protection is also important. A hundred pounds or more of metal slamming into itself at high speed makes a deafening sound.

When I was a graduate student making something in the machine shop, another user of this (excellent) departmental facility had just spent most of the day setting up his CNC milling job on the oldest, shittiest (and therefore least-time-pressured) 3-axis mill in the building. Whilst I was manually turning something on the lathe about 15 m away, he shut the door and pressed the 'go' button.

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.

Re: Have you ever hurt yourself from your own code?

#410

Post by NovemberWhiskey » Fri, May 28, 2021, 1:20 PM UTC

I've never hurt myself, but I have set the computer on fire.

Context: building an avionics test set with an integrated loads and measurements capability and complex relay switching network to allow different things to be switched to different loads and voltage drops measured. During software/hardware integration testing (first time that the hardware had been driven full speed) we found a bug in the CPLD that resulted in 28V being sunk into a 2A resistive load over a couple of PCB traces specified for 10mA; resulting in a large amount of magic smoke being emitted.