On Fri, 26 May 2017 14:30:15 +0100, Dan S. MacAbre wrote:

Fredxxx wrote:
On 26/05/2017 10:27, Dan S. MacAbre wrote:
Some of our doors have knobs, which we like (like idiots, we tend to
catch our sleeves on the ones with handles), but the problem with the
doors with knobs is that one's hand is a little too close to the frame
for 100% comfort :-) I wanted to fit some latches with longer backsets
(the 83mm ones seem about right), but they won't fit in the holes cut
for the existing latches. I need to enlarge them by a couple of mm. I'm
imagining that if I just try to offer the bit up to it, it will just
bounce all over the place, so I'm not going to try that. Right now, the
only thing I can think is to glue a bit of wooden pole in there and
start again. But is there another easier way, I could do it? I'm not
even sure that I could source the wooden pole/dowel of the correct
diameter.

Given I have these items at hand, I would simply use a Dremel and a
tungsten carbide bit to 'move' the hole a little.

The rest of the ideas seem an awful lot of faffing around for just 2mm
of wood.

YMMV

It's the hole into the side of the door that the latch body slides into,
not the one that the spindle goes through :-) I need to make it wider
and deeper to take a larger latch body.

Many years ago I had to do the same. Used a step drill to get the initial
diameter correct (only a few mm depth of course) then a spade bit the rest
of the way.
Looking at other comments in here, I reckon I was lucky to get away with it.
An auger-type bit would be less likely to bounce around, but might be too
viscious and pull in.
Something that I've used on chipboard, where there's severe risk of 'picking
up' and losing control with a twist drill, is to use a masonary bit. It's
almost 'backed off' and doesn't pull in sharply.

--
Peter.
The gods will stay away
whilst religions hold sway