Good afternoon! I am new to the forum and inexperienced in the subject, what I want to do is join two USB cables to give it more length, and for this I took advantage of the end of an old USB cable, of those that are no longer used, to join it to the microusb that use to charge the cell phone. The issue is that when I opened the new cable, I found that the ones I have to join (red, white, black and green) are covered by a metal foil and, around all this, copper wires .. What I did was remove the sheet that covered them and cut the copper, and along with the four colored wires this appeared: (They are like threads) what are they for? The short ones? [Img] https://cdn.yoreparo.com/uploads/imagen_post/0002/79/cf86e722b533e5428fe986b8db648244006b1bd9.jpeg [/img]

The wire is to prevent a cable pull from damaging the internal conductors. Just peel the tips and join with green, green, red and red solder and so on. To insulate them I like to use heat shrinkable, it is more neat and the final cover that would keep the patch closed can also be done with heat shrinkable.

the truth that without knowledge is a risk, they sell usb extenders and that they bring a circuit so that they work correctly, if you have something wrongly connected and the cable is bad, you will damage components and you will get more expensive the arrangement of the components that buy a usb extender

nothing happens if you cut them since they are only for security