why do most right-hand scissors not work when used with the left hand?
In: Physics
The thumb doesn’t move perfectly straight up and down, it moves in an arc because it stays the same length. This means it tends to press outward on the handle of scissors which presses the blades of the scissors together when used with the hand they were designed for.
Using the other hand (such as the left with right handed scissors) will tend to push the blades apart, offsetting the sheer force and letting the material trying to be cut to just bend and slide between the blades. That greatly reduces their effectiveness.
When you use scissors, you’re not just providing an up and down force to have the two sides meet, but also a rotational force to make sure that the cutting sides are going to be pushing against each other while they meet. When you hold the scissors in the wrong hand, that rotational force is in the other direction, which actually makes the cutting edges push apart, making the scissors far less effective.
The blades in a scissor is offset from each other, so they can pass each other. The blades themselves are quite thick. This means that the top blade will cover a lot of the paper from view. But that is fine as long as you can see the line you are cutting along. But if you hold a right handed scissor in your left hand the top blade will cover the line you are cutting along. So you do not see where you are cutting.
There are a few other reasons. A lot of scissors are built to shape to your hands making them more comfortable to use. But this obviously assumes you use them in the right hand.
They do work, but it is harder.
Left handed scissors didn’t exist when I grew up and any left handed implement was considered very odd.
Right handers don’t see the difference, so I give the left handed scissors and all them to cut along a line. They usually say there’s something wrong with the scissors.
Best trick: give a right hander a left handed cork screw and watch them struggle!
I am left handed. I have only ever used right handed scissors. Like everything else that’s made for right handed people it is perfectly possible for a lefty to use them. It’s just somewhat harder.
There are at least three reasons:
1) The handle is shaped for a right-hander, so some (not all) can be painful to use. Many left handed scissors don’t have this shaping, making them almost usable for a right-hander. Some shops will think that having a neutral grip makes it left handed (NO).
2) You need to apply some sideways pressure to keep the blades together. The natural squeezing movement of a lefty opens RH scissors instead of closing them (again, some, mostly cheap, not all).
3) Most importantly: You can’t see the cut line without leaning over the workpiece or twisting it towards you.
None of these makes using RH scissors impossible, just a bit more awkward. If you’re a lefty, the world is just irritatingly badly designed.
The third point has parallels all over. E.g. kettles and jugs where you can’t see the measurements. Rulers and tape measures which you want to hold on the zero or are upside-down. Wristwatches where the side-button gets pressed when you bend your wrist.
I’m left-handed and I don’t have a problem cutting things.
The main problem is that most of them are uncomfortable to hold.
Literally just put a pair of scissors in my left hand to try this out. They work fine feels awkward but they cut 🤷
The crosspoint on the scissors acts as a fulcrum and if you squeeze it with a right hand it pushes the blades together, if you squeeze with your left hand it pushes the blades away from each other.
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