Hi all, sorry to be so scarce these years. Any last confusion as to left vs right:
RED = RIGHT, best for right handed people
GREEN = LEFT, best for left handed people
Wish now that you were truly ambidextrous.
In an ideal world you always want to buy both Left and Right snips. Tin bashers always need to have both snips because they are very often forced to cut in akward places or on difficult parts of metal things. This can often happen in modding too, if you have to cut into corners or near bent parts. Parts of a case can get in the way so that you can't freely choose which side you want to cut from. Typically you use the snip of your handedness whenever you can, but switch to the other-handed one where you have to.
For all of these left/right handed snips, the idea is that the handles of the snips stay well above and clear of the metal as you cut along. This is accomplished by having the handles tilted up behind the blades. This allows you to cut curves, because the handles don't run into the metal on either side of the cut. On STRAIGHT snips, the handles are straight out behind the blades, and you can't cut curves easily at all (they suck).
One blade, we'll call it the TOP blade, stays above the metal cut, with it's edge approximately laying flat on the metal you want to keep. The BOTTOM blade meanwhile comes up from below as you squeeze the handles, and cuts upwards, bending and curling the offcut upwards and away. The idea here is that the TOP blade, which you can always see and keep aligned with the cut, stays fairly still. The metal under the TOP blade stays flat and undamaged while cutting, it's your keeper side.
The reason for the handedness preference can be explianed like this: Put your dominant hand / arm straight out in front of you, and pretend to hold some snips. Now turn your wrist around, as if to point the snips back towards yourself. You can turn either hand inwards until the snips point all the way back at yourself, about 180Â°, but only turn them at most 90Â° outwards.
Red Right snips cut a curve from the right towards the left.
Green Left snips cut a curve from the left towards the right.
Applied for a right hander: with Red Right snips held in the right hand, they can cut a leftward heading curve all the way back around towards you, 180Â°, without having to dance your body around the cut. But holding Green Left snips in your right hand, you can only go 90Â° outwards at most, and even then at an uncomfortable angle.
The other factor is about the force that it takes to bend the offcut upwards and away. Your wrist has to keep the snips vertical to the cut, so that you get a nice square edge. Using other-handed snips in your strong hand, that force wants to bend your wrist, and you have to twist as if lifting up with your wrists, which is much weaker than twisting as if pushing down. This makes it much harder to hold the snips square to the cut. Added to that, you can usually help bend the offcut upwards and away using your free hand, which further reduces the cutting and holding force required. But your spare hand is on the keeper side of the cut, so it's double tricky to reach across the cut to help tho offcut bend away.
Finally, If you want to be brave, try to do the switcheroo and drive with your weak hand. Practice on some metal you don't value too much. To compound the difficulty, you will be distacting a weak hand's tricky job by giving the strong hand anything to do at all, and it will steal back all that difficult attention that your weak hand needs to even work at all. In practice, on a few lucky folks in my old shop could ever do it well. So don't be disappointed in yourself if it's just not worth your time.
Cheers all, and happy modding.