I'm currently putting a bike together with recycled parts and want to get away with not having to purchase a new gear wire. On my first attempt to thread the RD wire I ended up fraying it, cutting off too big a length and having to purchase a replacement. The old FD wire is too short so I want to switch the wire from the right to the left shifter.

New cables are cut and 'sealed' in a way that they're easy to thread. 

For a used wire what is the best way to:

* cut the wire to prevent fraying?
* thread the wire through the cable outers and end caps without fraying?

It is relatively simple to thread the cable through the entry end cap and outer but even with removing the exit end cap it is difficult to thread through the last cap.