Why are the screws tightened clockwise to the right


It took thousands of years for small screws to be inven […]

It took thousands of years for small screws to be invented to be tightened clockwise and loosened counterclockwise.


Regardless of screws, bolts, or other threaded connections, there are two types of left-hand thread and right-hand thread.


Where are the left-hand threads used? In some parts that rotate at high speed to the right, you must use the left-handed screw, because the right-handed screw may loosen during the clockwise rotation of the machine, while the left-handed screw will become tighter.


For example: the screw for fastening the grinding wheel on the grinder is a left-handed screw; the pedal mandrel screw of a bicycle is used to ensure the right-handed place-the feed screw of the machine tool, etc. These places are all left-handed screws.



The screws we often use, whether they are mechanical equipment or the screws encountered in life, are basically tightened to the right in this way. What is the design principle here? Does it make sense?


In fact, most right-handed threads are designed this way for two important reasons:


1. This is the principle of ergonomics. The speed direction based on the axis of reference follows the right-hand rule. More than 90% of people use the right hand, which is convenient for most people to use.


2. The right-hand thread processing technology is convenient, especially in the processing of large thread turning.


If conditions permit, you can also try to turn the screw counterclockwise to the left, and then try to turn it clockwise to the right. Is it easier to turn it to the right?