OT: Why Righty Tighty Lefty Loosey?

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OK, its not strictly a woodworking questio.
But, from time to time I read comments form some "Engineering types" who might have the answer.
Now, wiseacres, I know turning to the right tightens screws and nuts and so for and turning counter-clockwise/Left, loosens/unscrews/etc.
But why? Is there some practical consideration, some engineering principle involved in the decision to make screws and nuts and such in this manner? Or, like a toilet flush, is it done just teh opposite in China? ;)
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Hoosierpopi wrote:

My guess is that most people are right-handed, and it is easier to twist your right hand clockwise than counterclockwise. (At least for me it is.)
That said, there are cases where the design calls for "opposite" threads to keep things from becoming unscrewed through normal use. Left-side bicycle pedals screw onto the cranks lefty-tighty, for instance.
Chris
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So it would be harder to loosen than to tighten. ;~)
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Up until some time in the 1960s, all Chrysler cars had right handed wheel nuts on one side of the car, and left wheel handed nuts on the other side, I don't know why. They did change to all right handed wheel nuts at some point in time. Probably because many people didn't know about them and spent hours tightening left handed nuts trying to get them off, eventually shearing the studs off.
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Like most all objects that spin and are held on by nuts or bolts they loosen in the direction that the object being spun would normally spin. It is unlikely that a nut or bolt will loosen if it has to spin faster than the object in the same direction that the object normally spins. Hense, the lug nuts on Chrysler vehicles had left hand threads on the wheels that were on the right hand/passenger side of the car. IF the cars used one nut on the center of the axel to hold the wheels on, all cars would still have left hand nuts on the right side of the car.
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Yep...
I had a '51 Studebaker Commander and a '63 Plymouth Valiant so I had experience with the other side of the car's lug nuts! &^%$*^!!!
Skip www.ShopFileR.com

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EXT wrote:

I was one of them. 17 and full of piss 'n vinegar with Daddy's car out in a snow storm. Hit a curb too fast and pfft goes the tire. Spent nearly all damned night tightening the lugs on that flat. Didn't have enough strength to shear the nuts off, but sure made it tough to finally get them started when someone suggested going the other way.
Bought daddy a new lug wrench the next day. The old one was...um..bent.
--
Tanus

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I wonder if that's the reason for the advice "If you can't get the nut to loosen, try tightening it and then try again." ;-)
Puckdropper
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Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
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EXT wrote:

Back on topic, check out your right tilt tablesaw or RAS. Lefty tighty 'cause if it was righty tighty, the start up jolt might spin the arbor nut along with the blade off the arbor. It's not a problem on stopping since shutdown doesn't have the jolt. In my early RAS days, I'd turn blue in the face trying to get the arbor nut off - until I noticed the threads on the end of the arbor. That was when you did a lot of blade changing as HSS blades were about all that was available.
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Got a left-tilt saw a few months ago. Seems absolutely unnatural to have a right-hand thread on a tablesaw. The tilt I got used to right away, but it'll be a lot of blade changings before I even start the wrench toward the proper side.
My British cars had knock-off hubs back in the day, and they were legitimately left and right thread.
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How hard is it to pull the wrench toward you to loosen the nut? Just like you always did.
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LRod

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Mid-1970s, actually, IIRC -- my first car was a '68 Dodge Dart with left-hand thread lug nuts on the left side. My brother had a '72 Charger that I'm pretty sure was the same way. But my '85 D150 truck has right-hand threads all the way around.

Because the rotational force applied to the nuts by the rotation of the wheels as the car is driven is counterclockwise on the left wheels, and clockwise on the right wheels. Hence, the lugs had left-hand threads on the left side, right-hand threads on the right side.
It took Chrysler quite some time to realize what GM, Ford, and everyone else apparently knew all along: that the magnitude of this force is small enough that just making the lug nuts a little bit tighter is a far simpler solution to a nearly-nonexistent problem.

Well, it *was* documented in the owner's manual. Not the manufacturer's fault if the buyer doesn't read it...
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Doug Miller (alphageek at milmac dot com)
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clockwise is the direction that a right handed person has the most twisting strength. beyond that, it's kind of one of those traditional things whose origins are lost in time.
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On Sat, 17 Nov 2007 22:32:04 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

Then all those garbonzos that put the bread-bag ties on backwards on Maier's bread are left handed, huh? Just one of life's little annoyances that crop up, especially before the morning caffeine kicks in... :)
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Yep, the machines are left-handed.
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Or, like a toilet flush, is it done just teh opposite in

actually...Chinese toilets don't flush in the opposite direction....not even in Australia.
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Robatoy used his keyboard to write :

They don't swirl at all here in Oz. Toilets on this end of the planet in the UK and at least some of the countries in Europe don't have as much standing water in them as I have seen in North America. The first time I went to a bathroom stall in the US, I saw the water level and I thought it was broken. Flushing is not done by a whirlpool effect but through the gravity feed of the water in the tank.
Just part of the rich tapestry of life I suppose.
Mekon
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Mekon,
I was impressed by the toilets in Oz (I know, I know...it dosent take much<g>). I don't understand why we cant adapt some of your construction stuff here in the US like the toilet design, having water drains in the middle of the bathrooms and laundry rooms, and slate roofs. Makes a lot of sense!
Skip www.ShopFileR.com
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Skip Williams submitted this idea :

We also have switches on all of our power outlets too, which a few North Americans have found variously amusing/puzzling and impressive.
Oh and if any of you folk from up over do happen to be in Brisbane, give me a hoy and I'll try to lay on a tour or two.
Mekon
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