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Comment by soligern | Hacker News Reader

What good is a mile to begin with. Just use kms and then we have a nice round figure. Being from the US and as someone that does a lot of woodworking, I’m very used to inches but I can’t do anything beyond basic calculations in inches and always have to pull out a very specific carpenters calculator. It’s not trivial to add up 2’13/32” + 5’11/16”, there’s too much carrying over and doubling to equalize the denominators to do easily in your head. That’s just addition, dividing is a whole other beast.

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Nautical miles are used in sailing because they correspond (nearly) directly to an arcminute of latitude which simplifies chart navigation.

IDK if 2.40625 + 5.6875 is any easier :)

Inches using base 2 for the fractions is useful.

Yeah, I don’t think woodworking is the best example for arguing that metric is better than imperial. In fact, it’s one of the few disciplines where the imperial system as a decent argument for superiority.

Metric woodworking just uses integer millimeters for everything.

Woodworking measurement has two forms: lumber, which is notional, pre drying, shrinkage and rough handling, and cut, which is required to be beautiful. Sometimes, it isn't about feet and inches as much as "the same"

Plumbing is another example where imperial works and is even used in Europe. It doesn't matter that a pipe is 3", it may as well be called "type B", since all you care about is if it's big enough for the purpose (you look that up in building code) and if the parts match together. The moment you need to perform calculations is when imperial becomes a total PITA to use.

Minimum radius is much more important in plumbing I think than metric/Imperial. And screw-thread.

WDYM by minimum radius? Are you referring to the part of my post where I wrote that you just look it up in the building code (as opposed to trying to calculate it), or when actually designing where the pipe runs?

The intersection of both. I did a very bad job of plumbing an electric shower into my flat in York back in the 80s and working out how to route the pipe to meet both ends requirement of where I could connect it into supply, and where it had to be to deliver water to the heater, was massively confusing. I am sure a plumber would understand this innately, but I wasted 2+ m of copper pipe trying to "route" it, without understanding the limits of how I could bend it, or cut and use a fitting.

The building code(s) only get you so far. There's also aesthetics.

Ah, well, I only did PEX and ABS for my reno, very idiot-proof so I managed. ; )

I made the mistake of watching (as a kid) a plumber use his own body to form the curves, and assumed "it's that easy" without taking in that he was 25 years past his apprenticeship and had bent thousands of pipes, and used a former almost all the time. It's a different game when its you, the pipe, and twenty needle-jets of water streaming out of the badly fitted olives, lack of PTFE (or too much) tools which don't fit, pipe with ugly crinkles in them, splits along the length...

Sorry, I dabble with woodworking and disagree heavily. I usually don't care for bigger precision than 1mm (so between 1/16" and 1/32"), and adding things up is a nightmare ("umm... 7 3/16" + 2 1/8" + 5 1/4" is... where's a goddamn pen & paper..."). Same with figuring out which line is which fraction of an inch on measuring tools. Things became tolerable once I got metric measuring tape.

Once you get past the dabbling stage it starts to get pretty natural. I don't think either system is better, the value is mostly tied up with what's on the shelves at the local home center and how your measuring tools are marked.

The stuff on the shelves is rarely sized precisely enough for the units to matter. I've bought 1/4" ply that measured much closer to 6.0 mm than to 1/4".

It's already natural when using metric, so I'll stick to it.

Sure, if tools are dirt cheap you can just sacrifice to Benford's Law and use base 10. If tools are not cheap, you'll learn to use base 2, one way or another.

I doubt I'll ever be able to quickly add fractions in base-2 (it doesn't happen often enough to train this), so pen+paper will always be a necessity if I wanted to stick to imperial. I could see getting the intuition for "which line is the eights vs sixteenths" over time though, but if the one-off calculations are going to be such a pain, I don't really see a point.

My FIL is a fine art woodworker (makes stupidly nice furniture, canoes that are functional art, etc.), and he uses both. He’s done it so long that he can work with fractions instantly in his head, but he also fully admits that metric is way easier for a lot of it, and so uses both as needed.

About the only example of imperial being easier I can think of is that the thin-kerf saw blades he buys are American, and thus are measured in inches - 1/16” to be precise. It’d be tremendously annoying to deal with 1.588 mm. If he had a 1.5 mm blade, of course, it would be the other way around.

It isn't easier, but 6.112cm + 14.446cm is fairly easy. Especially if you drop thousandths, which you can only maybe get when measuring with a caliper...

2405.25 + 5687.5 is easily 8092.75. But in both cases not using a calculator and not doing an operation on it at least twice (if it has no log) is a recipe for wtf, imo. An expensive mistake requires only one miscalculation.

> Inches using base 2 for the fractions is useful.

Why? You can't just say that without a reason.

(The numbers you cited above don't count, because you'd instead use 6.1 and 14.4 (or maybe 14.45) centimeters)

Certainly.

Let's say you are centering a 2 1/4" board on a 22" frame.

The edges need to be 8 3/8" apart.

It's a lot more common to divide lengths in halves (and quarters, etc) than tenths.

But say you have to divide a 8 3/8” board into 5 parts. That turns into an ugly 771/40. What do you even do with that using an imperial measuring tape?

I have never needed to divide a board into 5 parts.

But if I did that would indeed be difficult.

I regularly need to divide to build bookshelves out of 4x8 plywood sheets.

Easier to type into any general purpose calculator. It’s also so much more accurate when trying to enter into any CAD/CAM software.

It’s also easier to add up 10 different decimal numbers than the same number of mixed numbers.

Are you visually or mentally impaired? I don't mean it in any condescending way. I can add those on the spot by just looking at the numbers and tell you result immediately, that's primary school level math in Europe.

Yes I'm mentally impaired.

That's why I like to do things that are easier.

Inches only use base-2 fractions down to 1/64", then they switch to thousandths of an inch (thou), with base-10.

> It’s not trivial to add up 2’13/32” + 5’11/16”, there’s too much carrying over and doubling to equalize the denominators to do easily in your head.

Seems like straight forward arithmetic, but if using a calculator is a must, the HP 35s (RPN daily driver) handles fractional calculations elegantly without being a "very specific carpenters calculator":

  2.13.32 [Enter] 5.11.16 [+]

  8.09375

...and if you wanted that decimal as fractional display instead:

  [-->] [FDISP]

  8 3/32

Or you add 6.112cm to 14.446cm, which probably even children can do in their head reliably. But sure, you can do it using fantasy units, too :)

Now change that first number from 6.112 to 6.789 and watch that same child stumble.

I've always found it curious how Europeans pride themselves in speaking their native tongue + English...except its always a cultural flame war-inciting impediment when the communication barrier involves a mere arithmetic unit conversion. Doubly ironic when most of the world is consciously aware of what the prevailing USD exchange rate with their native currency is without complaint, whereas the average American simply doesn't have a clue how many Euros a US dollar gets them.

Similarly, if the Brits want to reference weight in stone, or Canadians want to sell me lumber in board-foot, I don't find that offensive in the least; I'm of the position that the impetus is on me to understand their measure, not for the one communicating to conform to my norms.

Why would there be any stumbling? Because it's two 6s? Because there's two carries?

The child would clearly have to mentally carry four times all the way down the chain:

    11 11
    14.446
  +  6.789
  --------
    21.235

What’s so difficult with that? Just use pen and paper for calculations, you’re supposed to write down the result anyway. It’s a simple math.

The goalposts set by the grandparent was reliable mental arithmetic by a notional child:

> ...which probably even children can do in their head reliably.

You're moving the goalposts.

An indefinite number of applications exist where we can make meaningful decisions all day without ever needing to write results down.

Really, this is primary school maths. I learnt about carries when I was seven.

Every single thread (both here and on Reddit) I've seen says 'oh, decimals are too hard'.

This is a terrible indictment of the American schooling system if your only defence against metrication is 'I can't do decimals'. It is you lot who have to catch up.

> This is a terrible indictment of the American schooling system if your only defence against metrication is 'I can't do decimals'. It is you lot who have to catch up.

To the contrary, if you read into the full context of this thread, the underlying contention isn't that we're incompetent at decimal arithmetic, but that the rest of the world (and apparently some Americans too) believes our common fractional arithmetic is too much of a mental burden, and I don't blame those individuals either.

Indeed decimal arithmetic is trivial to most grown adults, but that wasn't the point; the example was merely to highlight how just slightly changing a few numbers in the same sequence of operations serves as an effective counterpoint to the grandparent's assertion that "even children can do in their head reliably".

Americans are taught and handle metric units in compulsory school just fine, but most of us also practice imperial units on a daily basis as well. We're just not culturally predisposed to complain when everyone else conveys measure in the SI mks/cgs framework.

> common fractional arithmetic

I agree with the current of the thread, that mixed numbers are decidedly inferior to decimals. They're not harder, strictly speaking, but are more tedious, and this additional tedium introduces steps that people can make mistakes in. Fractions are also not easily parsed by standard desk calculators, and are not easily printed in a single line. They may even be mistaken by someone in a hurry as three separate numbers.

Decimals do away with all this unnecessary pain, and this really is the key point of metrication: it is a waste of time and effort to use non-SI units and convert back and forth or deal with mixed numbers. That's what people are complaining about: it is exasperating when Americans dredge mediæval units up in the 21st century, when we have a modern, simple, and unified system of units available.

> ...mixed numbers are decidedly inferior to decimals. They're not harder, strictly speaking, but are more tedious, and this additional tedium introduces steps that people can make mistakes in.

A counterpoint to this is the fact that there are close to a million employed carpenter tradesmen in the US whose average level of education is a high school diploma[1], and yet their trade operates almost exclusively on fractional arithmetic, most of which occurs mentally on the jobsite.

The point being that tedium is a relative measure of training and experience, and it goes without saying that those trained in only decimal form are liable to struggle with unfamiliar systems.

And if you think that's bad, try purchasing lumber from any lumber yard in Canada or the US; the trade's board-foot system[2] will really tickle your metric attachment.

> it is a waste of time and effort to use non-SI units and convert back and forth.

It seems the story is more like it's a waste of time to those who find value in what Americans have to say but are unaccustomed and insistently resistant to performing conversions. I don't disagree that there's certainly value in having a globally common measurement framework, and indeed an American who conveys imperial units in a European setting is liable to be chastised. But old habits die hard and last time I checked, we're not having this discussion on a .eu gTLD.

Now try imagining how the typical American feels when engaging with the rest of the world: SI units, (,) and (.) symbols reversed, left-lane driving, etc. We tend to just adapt.

[1] https://www.bls.gov/ooh/construction-and-extraction/carpente...

[2] https://en.wikipedia.org/wiki/Board_foot

It’s baffling to me how you twist and turn the perfectly clear explanation of the parent poster into some convoluted argument in favor of imperial units. Essentially, it boils down to ”we’ve always done it this way, we don’t mind pointless busywork, and doing stuff different to everyone else is a good thing“.

Sounds like a personal issue.

Tell you what, just keep it on that side of the Atlantic and continue buying our natural gas, and since we're so biased to a fault towards "we've always done it this way", we'll keep buying your most excellent products that conform to Reinheitsgebot.

Was that available on 48g perhaps?

Unsure with the 48g; trained myself since engineering undergrad days to not lean into graphing calculators. The feature existed since at least the 32sii, so it makes sense that successor 33s and 35s models also got it. Easily one of the most useful features that I've found for woodworking and converting arcmin/sec to decimal as the most common usecases.

I know of sexagesimal mode in 48g and used it, but haven't encountered anything for imperial units

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