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|parts = [[Bolts]], [[Nuts]]
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|tools = [[Wrenches]], [[Screw drivers]]
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Techniques
=Introduction=
By common convention, right-handedness is the default handedness for screw threads. Therefore, most threaded parts and fasteners have right-handed threads.
=Challenges=
Left-handed thread applications include:
Where the rotation of a shaft would cause a conventional right-handed nut to loosen rather than to tighten due to applied torque or to
fretting induced precession. Examples include:
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The axle nuts, or less commonly,
lug nuts on the left side of some automobiles.
The securing nut on some circular saw blades – the large
torque at startup should tend to tighten the nut.
The spindle on
brushcutter and
line trimmer heads, so that the torque tends to tighten rather than loosen the connection
In combination with right-hand threads in
turnbuckles and clamping studs.
In some gas supply connections to prevent dangerous misconnections, for example:
In a situation where neither threaded pipe end can be rotated to tighten or loosen the joint (e.g. in traditional heating pipes running through several rooms in a building). In such a case, the
coupling will have one right-handed and one left-handed thread.
In some instances, for example early
ballpoint pens, to provide a “secret” method of disassembly.
In artillery projectiles, anything that screws into the projectile must be given consideration as to what will happen when the projectile is fired, e.g., anything that screws into the base from the bottom of the projectile must be left hand threaded.
In mechanisms to give a more intuitive action as:
The leadscrew of the cross slide of a
lathe to cause the cross slide to move away from the operator when the leadscrew is turned clockwise.
The depth of cut screw of a “Bailey” (or “Stanley-Bailey”) type metal
plane (tool) for the blade to move in the direction of a regulating right hand finger.
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=Approaches=
Used to recall the direction a standard screw, bolt, or nut must turn to either tighten or loosen, right meaning clockwise and left counterclockwise.
=References=