On Tue, 28 Dec 2004 12:46:34 GMT, Lobster
wrote:

Unfortunately however, the hole's a bit tight for the fan, so I need to
enlarge the diameter by 1 or 2 mm - the sort of task I'd normally do
using a file or rasp were I working in wood or metal. But what would be
a good way of abrading a ceramic tile without busting it? (It took a
long time to saw the hole, so I'd rather not have to do it again!)

I have successfully enlarged/straightened cut-outs in tiles with a very
fine file - the flat one from a set of "warding files". It really
depends on how much of the tile there is left - I wouldn't want to do it
on any narrow projections.
--
On-line canal route planner: http://www.canalplan.org.uk

(Waterways World site of the month, April 2001)