I do not know what you mean by “use a wrench correctly”. I mean, I do not see how a person can use a wrench incorrectly.
Can you hint at what I am missing?
ADDED. There is a widespread standard for which way to turn to loosen a bolt and which way to turn to tighten it. Maybe that is what you refer to.
ADDED. If you use the wrong size wrench (i.e., slightly too big) you can “strip” the bolt (i.e., turn the hexagon into a circle, thereby making it impossible to wrench the bolt in the future even with a correctly-sized wrench). And as Romeo mentioned, not everyone is born knowing that the longer the lever, the easier it is for a person to apply a given amount of torque. And you can apply too much torque, thereby stripping the threads, which can lead to failure of the bolt to perform its primary function (holding 2 pieces together) and can make it impossible even to replace the bolt with a fresh bolt. On the other hand, if you do not apply enough torque, the bolt can shake loose. And speaking of shaking loose, you can forget to put in a lock washer where it is needed (with the result that the bolt shakes loose). So yeah, there are things to learn.
Gee, after I put myself in the right frame of mind, I can think of plenty of ways to use a wrench incorrectly. I withdraw the question. I would add however that people should not wait to receive training for using a wrench because it one of those things that can mostly be learned by experience (the purpose of lock washers being an exception to the general rule).
EDITED my first sentence to make it less likely to be interpreted as a potential put-down.
Removing and installing mechanical fasteners (bolts and screws) is more complex than you might assume. It goes far beyond selecting the right size tool, and turning it in the correct direction.
A mechanic develops these skills gradually over decades- a master mechanic would often have no trouble removing a corroded bolt that a novice mechanic would destroy for example. Conversely, they can also install a bolt in a manner with less chance of failure down the line.
Some (but by no means all) of the issues involved include:
How to brace your body to generate maximum torque in the right direction
How to feel when a bolt is beginning to stretch while tightening, and stop before you break it (the torque stops increasing when a bolt stretches, and you can learn to feel this point)
How to combine various tools to get leverage in tight spaces
Which penetrating lubricants to use for various levels of corrosion on various materials, how to apply them, and how long to let them soak
How much torque to apply when installing a fastener to minimize the chances of it loosening or failing
Which anti-corrosion or anti-seizing coatings to apply for specific metals in specific use applications (such as high vibration, saltwater, high temps, etc.)
Selecting the right type of socket (6 point, 12 point, impact, deep, shallow, etc. which have different strengths and weaknesses in different situations)
How to select the right fastener diameter, and material for a given application (sometimes a vehicle- especially a boat used in salt water will have the wrong sort of fasteners installed by an incompetent person previously, and a competent mechanic will need to know what to replace them with)
How to select and use bedding/sealing materials properly, for fasteners that must be waterproof or oilproof
How to use a torque wrench, and ensure that it remains calibrated correctly
As someone who operates vehicles in remote areas (offshore boating, remote desert driving) skill in using hand tools has made potentially terrible situations much better and possibly saved my life many times...
people are intimidated by the reference class of “hand tools” and so might fail to effectively use even the most basic ones.
You’d also be surprised how many people fail at basic physics (the longer the lever the more force you can transmit, so don’t hold the wrench in the center). I’ve seen people fail to correctly use screwdrivers, wrenches, pliers, etc.
-How to use basic hand tools efficiently and correctly (wrenches, soldering iron, etc.)
-Bayesian inference
I do not know what you mean by “use a wrench correctly”. I mean, I do not see how a person can use a wrench incorrectly.
Can you hint at what I am missing?
ADDED. There is a widespread standard for which way to turn to loosen a bolt and which way to turn to tighten it. Maybe that is what you refer to.
ADDED. If you use the wrong size wrench (i.e., slightly too big) you can “strip” the bolt (i.e., turn the hexagon into a circle, thereby making it impossible to wrench the bolt in the future even with a correctly-sized wrench). And as Romeo mentioned, not everyone is born knowing that the longer the lever, the easier it is for a person to apply a given amount of torque. And you can apply too much torque, thereby stripping the threads, which can lead to failure of the bolt to perform its primary function (holding 2 pieces together) and can make it impossible even to replace the bolt with a fresh bolt. On the other hand, if you do not apply enough torque, the bolt can shake loose. And speaking of shaking loose, you can forget to put in a lock washer where it is needed (with the result that the bolt shakes loose). So yeah, there are things to learn.
Gee, after I put myself in the right frame of mind, I can think of plenty of ways to use a wrench incorrectly. I withdraw the question. I would add however that people should not wait to receive training for using a wrench because it one of those things that can mostly be learned by experience (the purpose of lock washers being an exception to the general rule).
EDITED my first sentence to make it less likely to be interpreted as a potential put-down.
Removing and installing mechanical fasteners (bolts and screws) is more complex than you might assume. It goes far beyond selecting the right size tool, and turning it in the correct direction.
A mechanic develops these skills gradually over decades- a master mechanic would often have no trouble removing a corroded bolt that a novice mechanic would destroy for example. Conversely, they can also install a bolt in a manner with less chance of failure down the line.
Some (but by no means all) of the issues involved include:
How to brace your body to generate maximum torque in the right direction
How to feel when a bolt is beginning to stretch while tightening, and stop before you break it (the torque stops increasing when a bolt stretches, and you can learn to feel this point)
How to combine various tools to get leverage in tight spaces
Which penetrating lubricants to use for various levels of corrosion on various materials, how to apply them, and how long to let them soak
How much torque to apply when installing a fastener to minimize the chances of it loosening or failing
Which anti-corrosion or anti-seizing coatings to apply for specific metals in specific use applications (such as high vibration, saltwater, high temps, etc.)
Selecting the right type of socket (6 point, 12 point, impact, deep, shallow, etc. which have different strengths and weaknesses in different situations)
How to select the right fastener diameter, and material for a given application (sometimes a vehicle- especially a boat used in salt water will have the wrong sort of fasteners installed by an incompetent person previously, and a competent mechanic will need to know what to replace them with)
How to select and use bedding/sealing materials properly, for fasteners that must be waterproof or oilproof
How to use a torque wrench, and ensure that it remains calibrated correctly
As someone who operates vehicles in remote areas (offshore boating, remote desert driving) skill in using hand tools has made potentially terrible situations much better and possibly saved my life many times...
people are intimidated by the reference class of “hand tools” and so might fail to effectively use even the most basic ones.
You’d also be surprised how many people fail at basic physics (the longer the lever the more force you can transmit, so don’t hold the wrench in the center). I’ve seen people fail to correctly use screwdrivers, wrenches, pliers, etc.