The V-Groove Exterior Backup (green arrow) is where the blade backs up before initially plunging into the matboard on the outside cut of the V-Groove. 

Exterior Cuts cut into the matboard, not the fallout of the V-Groove.

Select the desired Cartridge Tab and then the V-Groove bevel type from the Current Bevel Type dropdown control before making adjustments.

• V-Groove

The V-Groove Exterior Backup, which is part of the outside cut of the V-Groove, is displayed on the V-Groove Configuration Map and on the associated field as a green arrow.

Check against the Configuration Map of the V-Groove you are cutting to determine specifically which cuts are the Exterior Backups.

Exterior Cuts, such as rectangles, cut into the matboard, not the fallout of the V-Groove. 

The inside of the V-Groove cuts first in a clockwise direction. These are internal cuts, which cut into the V-Groove fallout.

The outside of the V-Groove cuts second in a counter-clockwise direction. These are external cuts, which cut into the matboard.

The Exterior Backup is part of the second pass.

This is viewed from the front of the mat. If the Exterior Backup plunges the blade too soon, it makes the exterior backup too long on the outside cut of the V-Groove.

Decrease the Exterior Backup.

The corners will now meet up properly.

When making adjustments, click either the minus or plus button (-/+) at the end of the desired field about five or six times in the direction indicated. Click OK and do a test cut. Check the results of the cut and continue making adjustments until the desired outcome is achieved.

This is viewed from the front of the mat. If the Exterior Backup plunges the blade too late, it makes the exterior backup too short on the outside cut of the V-Groove.

Increase the Exterior Backup.

The corners will now meet up properly.

When making adjustments, click either the minus or plus button (-/+) at the end of the desired field about five or six times in the direction indicated. Click OK and do a test cut. Check the results of the cut and continue making adjustments until the desired outcome is achieved.

This is viewed from the front of the mat. For an Interior Backup where the blade plunges into the V-Groove fallout instead of the matboard, see V-Groove Interior Backup.