There are times when it is very hard to attach screws into the end grain of the wood. Either the wood splits very easily (even when pre-drilled), or the screws do not grab well. If that happens, here's a quick fix.

- Get a large-diameter dowel.

- Drill a hole in the board you want to fasten into with a drill bit equal to the diameter of the dowel.

- Put glue on the sides of the dowel, and hammer it into the hole.

- Saw off the remaining bit of the dowel and sand it smooth

You can now attach into the dowel since the grain of the wood in the dowel runs perpendicular, it will accept a screw much better.