Right hand threads

Who decided right hand threads would be the norm?

Probably the same person who decided which way was clockwise.

I don't know ... but I'm sure there's nothing sinister involved

MichaelG.

Maybe it has something to do with the predominance of individuals who are right handed. Dave

Most likely someone from the European continent, if threads was a British invention left handed would have been the norm. Niko.

Nice one Michael!

Leonardo Da Vinci perhaps?

Ed.

I reckon it's to do with right handers and they way threads were first cut in wood. Threads were marked on a wooden pole by wrapping a chalked cord around it. Then the thread was chiselled out using the chalked spiral as a guide. Right handed people are in the majority and they naturally wrap the cord to create a right-handed thread. It's quite awkward for right-handers to wind left-handed (and vice versa).

I've no idea why being right-handed is more common than being left-handed. I would have expected us to split 50-50. Where's a biologist when you need one?

Dave

PS Just seen Ed's suggestion about Leonardo da Vinci.  As he was a leftie, I may be in trouble!

Edited By SillyOldDuffer on 29/10/2017 20:24:13

Its strange that the French adopted RH threads when everything else seems to be opposite !
BobH

Despite (or is it indeed because of?) being a southpaw, I find that screwing clockwise is the natural way to drive a screw.

I was still surprised yesterday, replacing our oven fan motor. I saw and fully understood from the interweb that the fan retaining nut was left-handed, but which way did I "REALLY WANT TO" and still try to turn it to no avail? But successful repair job in the end .

Martin

Archimedes? But then everything is Greek to some all the time, and only most of the time to engineers until they ask the question here.

Go on, tell me he wasn't Greek.

Archimedes screws are left hand threads normally.

They were following the sun, which appears to rotate clockwise through the sky. Hence anticlockwise or left hand threads are 'widdershins' - against the sun.

Maybe so that cutting forces in the lathe when screwcutting are against the hefty headstock bearings, not against the more flimsy tailstock, and in those days fixed centre, when cutting a LH thread? (Remembering that in those days lathes were not easily reversible at the flick of a switch so screwcutting was most easily done in the normal forward rotation mode.)

Edited By Hopper on 29/10/2017 23:06:56

It makes it easier for dexterous people to tighten them.

Mike

I suppose it also aligns with common phrases like 'right-hand man' which assign the position of power or authority to the right hand. In many cultures the right hand is used for all the important things like eating, drinking, and social interaction, whereas the left hand is reserved for less appealing duties.

Ever since there were armies (and possibly before that) 'everyone' had to be right handed - couldn't tolerate lefties, with arms on the 'wrong' side.

Even down to about a hundred years sgo, those that were left handed were cajoled into using things right handed. Most machines, by then were only easily operated that way. I doubt if left handed scissors were made that long ago, for instance! (anyone know for sure?).

I put handedness down to mothers feeding babies (after breast feeding). Sat on knee, fed with right hand and baby will try to hold the spoon with the right hand. Possibly goes back to stronger heart beat on the left side (ventricle v atrium) and the way babies were carried.

As for screws, I have no idea except that most screws were tightened once and never removed, which meant it was just the easiest way for a right handed person to use them.

Edited to add that perhaps it goes deeper than hands (and feet).  One eye is nearly always the master eye.  That  may even have arisen from mothers feeding babies thatvway round.  Might just be chicken and egg - which came first?

Edited By not done it yet on 30/10/2017 08:12:06