john eastwood wrote:

Complete novice (and simpleton) needs to drill into two kitchen wall tiles
to put up a magnetic knife rack. The tiles are ancient, and if i crack
them or drill out of level tiles could not be replaced with matching ones.

It's also right near the sink where 'she who must be obeyed' will see it
all day. If i mess up, i'm dead or worse.

I've seen a workman drill into kitchen tiles and initially his drill goes
'all over the place' until it 'bites'. He's probably had a lot of
experience at this, i'm guessing that for me it would bite in the wrong
place.

Grateful for any tips on the 'safest' way for me to drill the tiles.
Thanks.

It would be a nightmare even for a professional to drill two holes in
exactly the right relative positions. Don't even try this unless the
rack design has already made provision for correcting for this, typically
by its own holes (through which the mounting screws go) not being
circular but elongated into ovals, one horizontal, the other vertical.

One alternative option might be to mount the rack on a wooden plinth.
Then you can drill the wall holes first, probably about an inch or two
further apart than the rack's own holes. Expect the wall holes to be
out of kilter, you can correct for this by drilling the plinth to match
the wall holes (use a piece of tracing or greaseproof paper, cut to the
shape of the plinth, aligned to lie exactly parallel to the tile edges,
to transfer the holes to the back of the plinth). Countersink the front
of the holes, mount the plinth to the wall, then mount the rack to the
plinth.

Option two: Consider using adhesive instead of screws. In fact, consider
screwing the rack to a wooden plinth as above, but then using adhesive
to fix the plinth to the tiles. You need to give the tiles a decent clean
first, and use something like Sikaflex to stick it on.

Option three (I think this is by far the best): Throw away the magnetic
rack and store the knives where they belong: in a drawer. To persuade
her of the wisdom of this, you could point out that in the drawer the knives
will stay clean, whereas if out in the open 24/7, they will catch all the
damp and grease you expect to be flying about in a kitchen, and in turn dust
will stick to them, etc.