"David Combs" wrote in message
...

One way to keep a support from slipping out of its hole would
be to glue the cylinder part into the hole.

Or you could shim the joint by finding a plastic straw of the
appropriate diameter, then snipping off a sleeve for each
of the shelf supports, so that it fits finger-right. This avoids messing
with glue.
--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)