Forum Replies Created
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Pedro’s cable cutter.
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Park Tools CN-10.
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The tools.
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Hey mods,
Considering these forums only have like three posts a day right now, would you consider moderating tbem?
The last three posts on this thread are very obvious spam.
If you let the posts stay up, they’ll notice, and you’ll get a lot more.
I don’t need a massive resource wasting statistical language model to tell me in weird “bro chat” format, or any format really, to go work out. Is there even any exercise science model behind it, or is it just “generate motivational workout text like a hyperexcited human cycling coach”? Like, if I overdid it yesterday, but said what your example user said, would it ever tell me to reconsider and take a day off?
I suspect that this tool merely creates the illusion of being coached. I’ve had friends go down LLM rabbit holes and end up with the illusion that they’ve created novel new physics. This whole bubble will pop in a few years, and good riddance to most of it!
Personally, I hate it.
SPAM
I see your “test reply.”
I used to “like” your posts, but it seems that they are now unlikeable.
Actually no, but hair
Actually no, but hair coverings, gowns, and shoe coverings are. Fortunately the woman who does most of the weighing has no beard, and I’m hardly ever required to go in there.
Who?
Who?
You forgot to include thaum variance.We’re not amateurs.
Our weighing room is an isolated, environmentally controlled, properly warded clean room.
We have some seven place
We have some seven place scales here, will weigh tens of grams to 0.0001 mg.
Ooh, did someone ask for a
Ooh, did someone ask for a measurement engineer/metrologist?
As others have mentioned, precision and accuracy are not the same. Going further down the rabbit hole, high quality measurement devices will specify at least:
Readability (or precision)
Zero offset
Non-linearity
Non-repeatability
Hysteresis
Temperature driftThe total uncertainty is generally calculated via the RMS (root mean square) of these.
Zero offset can often be ignored if you zero the instrument before use. That’s what “tare” does on a scale.
Non-linearity tells you how far it can wiggle around. For instance, if you calibrated the scale to read within 0.1 g at 10, 20, 30, 40, 50 g, that doesn’t mean it’s within 0.1 g at 25 g.
Non-repeatability would be how much the measurement would vary if you repeatedly made the same measurement in the same way.
Hysteresis is really related to what you’re seeing. The way it’s defined, though, is how much the reading can vary depending on the direction it’s approached from. If I tare the scale, then add a 20 g weight and see 19.8 g, then add another 20 g weight and immediately remove it, I may see 20.2 g, which means the hysteresis at that point is 0.4 g.
Temperature drift is just how much the reading could differ if the scale is not used at calibration conditions, usually 20 °C or 25 °C.
With scales, you also have errors due to buoyancy and local gravity, but those won’t matter for what you’re doing.
I believe what you’re seeing, since the scale has a mechanical component (something is moving a tiny bit) is stiction, but there’s a chance it’s purely electronic. You may be able to eliminate it by giving the scale a little shake before reading it. See how repeatable it is then. We have one model of dynamometer (engine torque measurement) that we calibrate where the procedure says to hit certain spots with a mallet before taking each point.
All this, and we also specify a coverage factor, generally 2σ which means two standard deviations. That gives us a 95% confidence interval, meaning even if I experiment with the scale and do all this math. and tell you the total uncertainty is ±0.35 g, it could still be expected to read outside of that interval 5% of the time.
I hope this brief, non-mathematical summary helps.
