Can I get a hub with 3 USB ports and a SWITCH on it then i can connect the External hard drive to the middle port via USB and each of the other ports to each computer via USB . And when using either computer use the switch to connect the desired computer
Long winded but a dummy here
Even if you did, you'd have to remember to "safely remove hardware" before switching. Much simpler would be to connect it to one of the computers and share it. That way, you'll always have access from either computer without any further outlay, or any complications.