26 May
2004
26 May
'04
7:32 p.m.
On May 27, 0:18, R. D. Davis wrote:
While there's nothing extremely heavy on the
shelves - e.g., one
shelf
contains a Canon laser printer (the square one with a
CX engine),
about 40 full-height 5-1/4" hard drives, an 8" floppy drive and a few
other things, I noticed that some of the items on some of the shelves
appear to be leaning slightly. It turns out that the boards are
sagging a bit towards the center, so it's just a matter of time
before
things begin to go crash. Not sure how soon that
might happen, but
this sagging has occurred fairly quickly, or so it seems.
Perhaps this will reassure you a bit. This happens gradually over time
to particle board (we call it chipboard over here), and it probably
hasn't happened suddenly -- it's just that you didn't notice until it
reached some threshold. The board is very flexible,and it will bend a
long way before it gives way. It's very common to see sagging shelves
especially where the suports are at or near the ends instead of about
1/4 of the way in (so the forces on each side balance better). It's
also very common to see cabinets (chest of drawers, kitchen cupboard
standing alone) with sides bowing outwards. I've seen a chipboard
shelf sag so much it slipped between the end supports, but rarely seen
one snap. For bookshelves, using 5/8" chipboard, a general
recommendation is no more than 2'6" between supports, assuming the
shelf is about 50% deeper than the books.
--
Pete Peter Turnbull
Network Manager
University of York