Use of "by" before "using"

Question

1. Infusion cannula entry sites are anesthetized with 1% lidocaine with 1:100,000 epinephrine and small incisions are made using a #11 blade.
2. Whenever a file is opened using fopen function, a file pointer is returned.
3. The area selected for developing is cleared using bulldozers, either by cutting the trees with a V- cutter or by walking the trees down with the dozer raised about 3 feet off the ground.
4. Using a screwdriver, remove the four screws holding the cover in place.
5. Four specimens each of 38 mm in diameter are cut using the appropriate cutter.

In these five sentences using has been used in different ways. But by has not been used before using. Will it be wrong if I use by before using? Why will it be wrong? If using of by in this case is wrong, please tell me when I can use by using.

Answer 1

Peter's comment is your best answer so far. He said,

"Why do you think using is used differently in each example? Its usage means by means of / by way of. Replacing using with by using would not change the meaning or understanding, though in #4 it would be awkward and the sentence should be inverted to sound natural."

It will not be wrong if you say "by using," it just is not necessary in these examples. It's a matter of style and personal preference. By using "by using," you are creating a prepositional phrase. :-)