I've crowned hundreds of guitars to the point of needing to buy multiple replacement crowning files, thanks to stainless steel frets. I will only ever use Stewmac Z-Files, I won't ever touch a fret with any other file. The V groove ensures the file never comes close to blowing out the top of your crown and gives you the confidence to knock that crown out fast with consistent results. The way the file is made you also have no risk of tearing up the fretboard. I've taught many people crowning and I've seen many of them blow through the tops of their crowns, forcing them to re-level the frets. I've also seen people manage to slice the fretboard up parallel with the frets from the edges of those normal crowning files. Even safety edged ones. Rookie mistakes? Sure. However, I've never seen those mistakes happen with a rookie using the z-files. If you only use nickel frets, you'll only need 1 file forever. If you use stainless steel, it'll take you a LOT of crowning to wear it down. Buy once, cry once.
https://www.stewmac.com/luthier-too...-crowning/stewmac-z-file-fret-crowning-files/
