This is over the Cellulosic root. The bevel angle is the same as for a Basic root at 37.5Degrees (judging grinding a shallower bevel-angle freehand with an angle-grinder seems problematic). However, with bigger root-face, the entire groove is narrower.
Fill and Cap done with 2.5mm dia "Bohler EV50" 7018's on DCEP - current 95A fill, 90A cap.
(Richard Smith, 17 May 2010)