"Dave Liquorice" wrote in message
ll.net...
On Sun, 08 Jun 2008 11:42:41 +0100, Dave Plowman (News) wrote:

I've not had the confidence to use a centre punch, which does sound a
good idea.

'Tis, it's what I use, or a nail. It just needs a very gently tap to break
the glaze. I sometimes work the tip of the punch (nail) a bit to get a
good start for the drill. Don't bother with a pilot but do use one of
those "universal" drills rather than a standard masonary one.

--
Cheers
Dave.


The main reason that I put a small hole through first, is that the smaller
drill flutes have less glaze to get through before starting to cut the
actual tile substrate. Also, the smaller flute area at the tip allows a
greater pressure to be applied which can help with hard tiles, and to keep
the drill tip temperature down. It also gets you into the wall behind
easier, without having to apply hammer action with the drill shaft through
the hole in the tile. Once you are through with the small hole, a larger
diameter drill to suit the shoulder of the plug, easily removes the
additional 'ring' of glaze, and opens the hole in the tile with a minimum of
stress. If you don't follow all the way in with the larger drill, when you
insert the wall plug, it will grab nice and tight at its tip, into the
reduced size hole. When you then whack the screw in with your electric
screwdriver, it tightens nicely as the screw gets to the bottom of the plug,
and doesn't 'run away' with you, as is so easily done when driving with a
high torque electric screwdriver, and crack the tile.

Arfa