Advantages and disadvantages of knife, pencil sharpener and pencil sharpener.

Although it is convenient to sharpen a pencil with a pencil sharpener, the nib often breaks because the blade is not sharp enough.

Although the pencil sharpener does not have this problem, it also has two disadvantages: first, the sharpened nib is too sharp, which is easy to cut the paper when writing, and the nib is easy to break, because the thickness of the nib is very different, resulting in uneven writing; Second, the cutting amount of the blade or milling cutter on pencil lead is too large, and most of the lead cores are actually cut off rather than cancelled, which is a great waste.