The reason i suggested what i did was that had to cut down the 30mm and 20mm rails for my build. I did this but putting the rod in the lathe and used an angle grinder to shorten and face off the ends. This worked great so should not see why it would not work in a mill/ vertical drill to do the same on smaller diameter rod. The fact that the abrasive disc would pick off the burs from the edges should prove quite well and if you use a pecking motion then should be no reason why should end up with blueing (gaps btween pecks)? my second idea was to use the very small mini drill cutting discs (they do not last long)