The horizontal panels do not line up with the face of the assembly.

REASON 

Horizontal boring machine is not drilling accurately from fence stops.

SOLUTION

Check the calibration and/or fence stops on your horizontal boring machine.

REASON

Edgebanding is being taken off part size when cutting panels. Drilling machine has banding applied before being drilled.

SOLUTION

Check edgebanding for correct thickness in software before creating machine code.

REASON

Dust has accumulated in the route.

SOLUTION

Blow off parts prior to assembly to remove any extra dust.