
Originally Posted by
Simon Barden
Gibson use a set of stings to set up the guitar, then almost the last thing they do is hit the strings into the saddles with a hammer to notch them, then fit a new set of strings.
Otherwise (if you don't want to risk that), if you look at pre-notched bridges, you'll see that they don't have notches that are string-sized, they are simple V-shaped and all the same size/depth (well some do vary but it's rare). So all you need for the bridge is a low-cost triangular needle file.
You can of course use nut files to do it, but as you haven't got any, then I'd suggest the needle file route. Just make sure you mark the positions carefully first so that the strings are evenly spaced and the E strings are running parallel to the fretboard edges.