@canadianeh I would like to chime in here. I bought a set of 4” corner braces in a package that come with screws to mount an IKEA wall cabinet on the end of my Reefer 250. You definitely should drill pilot holes where the screws go. Choose a drill bit slightly smaller than the screws. You hold the screw of the size you’re using by the head with one hand horizontal and hold a drill bit with the other hand horizontal just on top of the screw touching it. Look straight down on them and edges of the threads of the screw should stick out a little beyond the edges of the bit. Now drill your pilot holes where they go. When you screw on the screws there should be minimal resistance, the screw should go all the way in snug without stripping. If your screwdriver keeps popping out of the screw grooves then the pilot hole is too small in diameter.Hi did you have to pre-drill holes on the IKEA cabinet before you attach the L-brackets ? Which size of drill and screw you are using?