Why righthand threads?

[vintagengineerParticipant @vintagengineer]

Why are righthand threads the norm and who decided it?

[BazyleParticipant @bazyle]

Most people are right handed. A stoneage man holding a spear rotates it with four fingers pushing it round rather than anticlockwise driven by just the thumb and the fingers tending to slip off. Try it next time you are killing a mammoth.

[egaParticipant @ega]

The left is “sinister” ie associated with the dark side. And, as Bazyle suggests, the “Force” is stronger when applied right-handed.

[noel shelleyParticipant @noelshelley55608]

10 out of ten, Bazyle, go to the top of the class – and a spot on answer ! The simple mechanics of the wrist and fingers on the right hand make it the easiest way for most of us !  Noel.

[JAParticipant @ja]

Why are some people left handed? While the right handed answer makes full sense it seems a little convenient.

JA

[JAParticipant @ja]

Thinking about this further I am no longer convinced. On either hand I can rotate it in either direction with ease and I am not ambidextrous. I suspect a new born baby, or a little bit older, would have no problems in either direction.

Our model engineering club has a scheme for teenagers to build a useful model. Some of the mentors were surprised that their spacial awareness did not match.

JA

[JasonBModerator @jasonb]

The force argument does not work when the nut or bolt head is below the item as those who spend their time with their head under a bath or basin will know.

I blame whoever invented the clock otherwise they would not tighten clockwise!

[Nicholas FarrParticipant @nicholasfarr14254]

Hi most people would be able to tighten both a right and left hand nut of the same size and pitch, to the same amount, just try them with a torque wrench at the same setting. I dare say right hand is preferable for the majority of people though, but how that came about, I don’t know, but I was encouraged to hold my knife in my right hand, and my fork in my left hand, when I was a child leaning how to use them, but my younger brother couldn’t get the hang of it that way round, and has always been left-handed, and is the only left-handed one in our family.

Regards Nick.

[Howard LewisParticipant @howardlewis46836]

Maybe it dates back to when village blacksmiths made their own nthreads, and then when Whitworth standaedised threads so that all would be interchageable.

Howard

[egaParticipant @ega]

Imagine a right-handed smith filing a thread by hand; this would naturally produce a RH thread.

Thanks, Howard.

[Howard Lewis]

On Howard Lewis Said:

Maybe it dates back to when village blacksmiths made their own threads

If you take a wider view of threads than just on screws, as helical items, the blacksmith came to the party about 1000 years too late.

Think of ancient technology, the Archimedian screw for raising water.

Again, to take a wider view of clockwise/anti-clockwise, a preferred direction of rotation likely existed long before clocks. Think on animal-powered corn grinding.

[alan ord 2Participant @alanord2]

ega, just for info in Italian the word left is pronounced sinistra (probably spelt it wrong), Sinister does come from left handed people who many years ago were few and far between and hence were strange sinister people who were different to the norm.

Alan.

[paul raynerParticipant @paulrayner36054]

Mmm. Good question. Maybe because homosapians started out in the North of euraisia? And in the northern hemisphere water go’s down the plug hole clockwise?

[Nigel Graham 2Participant @nigelgraham2]

Howard –

I wonder if village blacksmiths ever made many screws. Perhaps large, coarse ones for fruit-presses and the like, but a lot of equipment was held together by rivets for permanence, slots and tapered cotters to allow disassembly; all much easier to make. Woodwork fastenings were mainly dowels and nails.

Industrial manufacturing evolved to making studs, bolt and nuts well before Sir Joseph Whitworth’s work; but what “standardising” there was, lay within the individual company.

 

Ega-

You could be right there. I sat back and considered how I, a right-hander, would file a groove at an angle across a steel rod.

I mimed filing outwards-rightwards, holding the handle in my left-hand and the blade end in my right so producing a left-hand thread. I do occasionally file that way to help keep the surface somewhere near flat or straight. However, even miming the action the opposite way (right hand pushing the file) feels a lot less awkward for me.

 

DC31k –

Mentioning clocks, think of the direction in which Northern Hemisphere sundials “work”. It would have been natural to make mechanical clock hands revolve in the same hand as the shadow, literally, “clockwise”.

So perhaps by extension, clockwise to tighten a screw.

What was the typical hand for the Archimedian Screw in archaic times?

It seems they were often made to be rotated manually, the winding-handle being on the shaft protruding from the top of the slanting cylinder. For a right-handed operator standing with the barrel extending down to his left, and winding the handle clockwise as viewed end-on, pushing the “top” away from him, would be the physically easiest way. So needing a right-hand helix.

….

I recall also reading that one old screw-making technique was to wind two parallel wires round the core rod, remove one and solder the other in place; but it cannot have been very strong.  How the nut was made, was not described.

””’

“Sinister, Dexter, Sinister, Dexter, Sinister….”

{From Monty Python’s The Life Of Brian.}

 

[not done it yetParticipant @notdoneityet]

Likely need to go back to when our antecedents came down out of the trees.

Monkeys have no real preference of right- or left-handedness.  Apes are predominantly right handed.

Families of plants tend to have the same whorl directions.  Flora evolved before fauna.

Humans are more right-handed than chimps.  This may be down to war-mongering/hunting.  All armies operate with the weapon on one side during operation.  It separates the weapons and avoids clashes between adjacent warriors/soldiers.

Over the last couple(?) of centuries most things were made for right hand operation – children were forcibly converted to being right-handed, for several/umpteen generations.

Our hearts are slightly to one side of the chest and mothers likely held babies such that the child was closest to her heartbeat.  I doubt that we remember which breast was the most favoured, in our early life.

Maybe the master eye affects which hand we use?  My left eye is the master, but the only thing I do is shoot from my left shoulder.  For everything else, I am right-handed (I think).

It used to be about 8% were left handed, but there are many more ‘left-hookers’ these days.

We write from left to right on a page.  My daughter writes with her left hand – and that has always been regarded as kack-handed but she has coped OK for 50 years!

Left or right may be developed from mother, who either fed the baby from behind or in front – the baby would/might reach out for the spoon/food with the closer hand?

All the above means we likely need to look a lot further back than Whitworth threads.

 

[Bill PhinnParticipant @billphinn90025]

NDIY says we write from left to right. True for many of us, but for millennia Chinese, Japanese and Korean characters were written down the page in columns, and from right to left. Books printed in Taiwan today can still frequently be found with characters written down the page. I have one or two myself printed this way and bought in only the last twenty years or so.

The early Greeks wrote in a style called boustrophedon – “as an ox ploughs”,  i.e. from left to right on one line and then on the next line from right to left (with the letters backwards) and so on.

I was right-handed for the first twenty-one years of my life and have been left handed ever since. The changeover can be done, but it takes years to get to the point where doing things with the left hand feels as second nature as it once did with the right. The learning process is helped when you have no choice in the matter.

I’m not sure the mother’s way of feeding her baby can massively influence handedness, as a mother close to me had to nurse two offspring of exactly the same age at the same time with one on one side and one on the other and yet they both grew up right-handed. I think each had a favourite side as well.

 

 

[not done it yetParticipant @notdoneityet]

I knew that some wrote vertically but wasn’t sure which side of the page they started.  Thanks for that.  I’ll try to remember it the next time I see chinese writings!🙂

[JohnFParticipant @johnf59703]

Could it be historically related to Archimedes screw ?  most pictures seem to be in RH format but interestingly in Wiki the animation is LH !  I haven’t seen anything concrete but the Archimedes screw is probably the first of its kind, not a thread as we know it today the principal is the same.

However it is just “natural” to turn things clockwise using the right hand and as has been said the majority of us are right handed — I am mostly left handed, I say mostly because I have no problem using RH only tools e.g. a micrometer, some particular wood planes — but generally I plane left handed, write left handed etc etc.

John

[not done it yet]

On not done it yet Said:

… It used to be about 8% were left handed, but there are many more ‘left-hookers’ these days…

The top 8%, naturally.

George

[JAParticipant @ja]

The only thing that makes sense to me is that the shadow on a sundial, in the northern hemisphere, moves clockwise. And then to clocks which predate modern screws by a few years. I am not sure about Archimedes pumps since their use was, historically, limited to the eastern Mediterranean (I think). Of course the shadows at Stonehenge move clockwise.

Did that brass ?astronomical? device dredged out of the sea near Greece about 150 years ago use right hand threads?

JA

[JA]

On JA Said:

cut- Of course the shadows at Stonehenge move clockwise.

Hi, when it was believed that the Earth was at the centre of the Universe, I suppose those in the northern hemisphere who believed that, could be forgiven to believe that the Sun and Moon were going clockwise, and so thought right handedness was the correct way to go, maybe.

Regards Nick.

[Neil AParticipant @neila]

I don’t think the Antikythera Mechanism used any screw threads, watching the Clickspring videos it is either rivets or tapered wedges.

I suspect that the right hand thread simply evolved over the centuries, mainly because as has been stated, most of the population was right handed and the natural tendency is for the right hand to rotate in a clockwise direction. I doubt if there was any real conscious effort to produce a right hand thread, it probably just felt more natural.

Could the direction of the shadow of the sundial in the northern hemisphere have something to do with it? I don’t believe we will ever really know. It was a very thought provoking question, kept me occupied for a long time trying to find some sort of answer.

Neil

[not done it yetParticipant @notdoneityet]

On     The top 8%, naturally.

George

About twenty years ago, I used to occasionally invigilate at GCSE/GCE examinations.  I once counted up the left and right handed writers.  The result was surprising for me – 17% were writing left-handed.

My shooting gloves of the 1970s were only supplied as about 8% left-handed, which agreed with my earlier knowledge on the topic.  Whether my result of 17% was typical of the whole population, I don’t know – as the population for that statistic was low and could be skewed by local factors.

4 million years is more over-powering evidence than local humans who made decisions long before mechanical threads were invented.  This thread is quite ‘parochial’ in that respect.

[Howard LewisParticipant @howardlewis46836]

Village blacksmiths did make their own nuts and bolts (Probably all unique)

Making the nuts must have been a real problem, so they tended to be few and far between.

The rotative winding engine at the Levant tin mine in Cornwall contains the minimum of nuts and bolts.  The flywheel was retained by tapered cotters that had beem driven home with heavy hammers.

Howard

 

 

[not done it yet]

On not done it yet Said:

I used to occasionally invigilate at GCSE/GCE examinations.

Any particular subject?

[Author]

Posts