Is it a fault when your racquet touch the net when you kill the shuttlecock? If it is, how can we prevent it when we want to smash it down?
I find it easier when you grip the racket on the cone or close to it. It does sacrifice power but it also makes it easier for you to stop the racket.
For very loose net kills, forearm pronation only will be okay (like smashing, but cut off the motion from the beginning and end). For tight net kills, use finger power - hold the racket in place, wait for the shuttle to come very close to the racket face, and then squeeze your fingers. Almost no wrist movement is needed, and definitely no arm movement. For extremely tight net kills, only the "brush net kill" action will suffice. You must be ready before the shuttle comes, hold the racket and wait, then make a short, sharp swipe from right to left without moving your racket forward. A very slight incline of the racket face into the court will help. The brush net kill is almost impossible to perform with a backhand.
I disagree. It may be harder, but I wouldn't go as far as "almost impossible". i.e. if I can do it, it can't be that hard (with practise)
I doubt if I could. Yes, left-to-right. I've never done it in a game, only in practise. But then, I'm currently too slow to need a backhand brush kill so I don't even practise it much. I think I've only ever done one forehand brush kill in a game.
Don't let the lack of success in games thus far deter you. If you can do it in an easy practice situation, then you may find that when other elements of your game are better, you suddenly gain the ability Do you feel that a (very) slight inward incline of the racket face helps brush net kills? Come to think of it, this probably comes naturally without thinking.