The RAVEN uses the scale sensors on the back roller to find the location of the back edge of the workpiece.  To do this RAVEN moves the board out from under the back roller looking for the pressure to drop off, then moving back under the roller while mapping the output of the scale sensors.  The RAVEN knows that it can not accurately determine the location if the pressure increases when it is looking for it to drop off,  the pressure decreases in steps or the mapping is significantly different between going off and going on the roller.  If any of these conditions exist, you will get a notice of  “Edge delta missed”. In some cases, the problem is just noise in the readings and a retry will succeed.  If a retry does not succeed, then restart the project being sure to resolve the problem with the workpiece. 

Possible causes of an Edge delt missed

1. Load the workpiece with the back edge just beyond the back roller to minimize the search range.
2. Transitions in the thickness of the board will result in the reading going up or dropping in steps.  Move the workpiece so it will not see the transition is not in the sureach area.
3. Loading the workpiece on top of the squaring or sliding plate. When this happens a pop is often heard when the RAVEN starts to move the workpiece. The “pop” is the workpiece dropping off of the plate resulting in  a step pressure drop.
4. The pressure needs to drop off quickly so if the back edge has a large angle or curvature to it then the pressure will drop off slowly and the edge will not be  accurately detectable. 
5. If the workpiece cantilevers when it comes out from under the back roller the mapping of the pressure will differ significantly between going off and going on the roller.