Why do caps (and screws) s***w down clockwise and up counterclockwise?

Question

Why do caps (and screws) s***w down clockwise and up counterclockwise?

Answer 1

They all don't, you can get reverse threaded nuts and bolts.

Why is CW tighten and CCW loosen?

Purely arbitrary, they could all be the other way, and no one would suffer.

Somebody made a decision long ago, and it became a standard.

Wikipedia says:

Nearly all threads are oriented so that a bolt or nut, seen from above, is tightened (the item turned moves away from the viewer) by turning it in a clockwise direction, and loosened (the item moves towards the viewer) by turning anticlockwise. This is known as a right-handed thread, since the natural s******g motion for a right-handed person is clockwise, and is the default because most people are right-handed. Threads oriented in the opposite direction are known as left-handed.

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Answer 2

The threads are right hand, as in that is the way they are cut.  If it is a left hand thread it would be the opposite.

Answer 3

the threads on all screws and bolts are standard right hand cut at 29 deg.

you have regular s***w type ,and there is acme type threads you also have single pitch double pitch and triple pitch the more pitch to the threads the faster the s***w or nut will turn on the threads..on subs and ships the hatch doors have triple pitch acme threads,this is why you see the handles turn fast and close more quickly..and in some cases you have left hand threads,the older army trucks had left hand threads and right hand threads on the lug nuts so they don't loosen up when driving..and left hand threads are not as common as the right.it depends on what you want to fasten and which type of thread you want to use....

Answer 4

The reason for the clockwise orientation of most screws is that supination of the arm, which is used by a right-handed person to turn a s***w clockwise, is generally stronger than pronation.  Hence you can make a s***w or cap tighter more easily than you can make it looser.  And making a s***w hold or a cap tight is their whole purpose.