jim evans wrote:
I need to screw something to the bottom of a desktop made of 1"
particle board (the upper surface is wood veneer). It will experience
a fair amount of load, so I need the screws to hold securely. If it
were solid wood or plywood I would be confident it would hold, but my
experience is particle board does not hold screws well -- they crumble
out.

So, my question is, how can I put screws in the particle board such
that they will hold securely?

jim

The standard ways is to drill a hole the size of a dowel and glue the
dowel in the hole, then drill a hole for the screw in the dowel.
First you need a Forstner bit which drill as flat bottom hole and you
need to pick an appropriate size. 1/2" would probably be ok, but
3/4" or 1" would be needed for a heavier weight. Or, you could just
glue a piece of 3/4" board on the under side and put screws into the
board.