Could someone please clarify the grain wedge concept? (I understand how to read the direction of grain). I am imagining a hypothetical perfectly flat inclined plane with a hole cut in the middle. Is the grain wedge only present underneath the hole when the grain is against the usual break direction (ie a single grain wedge)? Or, is there a second grain wedge directly opposite to that (i.e. above the hole but again where the grain lays opposite to the direction of the predicted break towards the fall line).