ROBERT SORBY EASYBEADER

Used trailing, ie. Set the tool rest so that the tool is angled slightly down when the cutting edge is on the centre line. Dare I confess to not being a fan of all the fancy new tools that are invented each year, but this tool really does work well and surprised me by cutting a very clean bead even on a Zebrano clock face.
Start with the handle up, then bring the cutting edge into contact with the work below centre. Rather than just levering the tool into the work, wiggle it (technical term) very slightly from side to side as you pivot the cutting edge up to the centre line to make a perfect cut.
Sharpen by flatting top edge with oilstone or Ezelap diamond hone.