On Friday, 26 May 2017 11:00:45 UTC+1, Dan S. MacAbre wrote:
tabbypurr wrote:
On Friday, 26 May 2017 10:27:57 UTC+1, 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.

A flat bit would go out of control. A spiral fluted bit close to the current hole size could be pushed sideways & cut, if not ideally. You might also get mileage out of those filing drill bits, but I bet a big fat spiral blacksmith's bit would be much better - and more expensive.

Yes, I only have flat bits, and I'm too scared to even contemplate
pushing one of those at the hole.

it would not go well

I like the look of those spiral
fluted bits, assuming that you mean those stepped conical things that my
first search has found?

no, I mean blacksmith's drill bits. Assuming you want to move the hole sideways. If you wanted to enlarge it all round the stepped things would almost do that.


NT

On Friday, 26 May 2017 11:29:24 UTC+1, Dan S. MacAbre wrote:
Dave Plowman (News) wrote:
In article , 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.

If the hole is nearly in the right place, enlarge with a round wood file?

If it is miles out, you'll have to plug it and start again. You can buy
plug cutters in most tool places - you cut a plug from a similar type of
scrap wood and glue in place.


It's just a couple of mm,

then file it

but too deep to file, I think. I hadn't heard
of plug cutters, but I'll take a look.


NT

On 5/26/2017 1:21 PM, Martin Brown wrote:
On 26/05/2017 11:48, Dan S. MacAbre wrote:
DICEGEORGE wrote:
glue/screw/nail an offcut to the outside / other side of the door.
drill new hole into that and through the door.
remove offcut

[g]

It might work if the offcut is at least as thick and strong as the door
being cut into, but the breakthrough into the asymmetric cut is likely
to be traumatic and difficult to control throwing the drill hard.

I was thinking of that after I posted. I'm not sure that the flat bits
I have will continue to go straight once they're in the hole, although
they do have flat sides, which I suppose will help, and then I just have
to hold it straight.

It is getting difficult to work out what you are trying to do. I
imagined a hole *through* a door for a handle but elsewhere it sounds
like you are talking about a blind hole into the door frame.

If there is a hole right the way through you could trace out the shape
and use a fret saw to cut the extra part out.

There are hybrid chunky drills that are midway between a twist drill and
a milling tool or a cone step drill which might just work if it is long
enough to be centred on scrap offcut nailed to the far side. Even so you
are going to get a kick off it every time the cutting side bites.

It does sound like the first thing I should try,
just to see how it goes. The wood (oak) is hard, which I think will
help to control things a bit.

Unfortunately it will make it incredibly difficult to control once you
have a cut into hard material on one side and no resistance at all on
the other probably flicking the drill out of your hands.


Sometimes that happens (and I have bent spade bits that way) but if you
are only looking for a small increase in diameter it is sometimes
possible. You feed the drill in vary gently when it is running fast, if
you are lucky it cuts a conical entry which follows the axis of the
original hole. Once you get a little way in, it becomes self centring.

On 5/26/2017 8:45 PM, newshound wrote:
On 5/26/2017 1:21 PM, Martin Brown wrote:
On 26/05/2017 11:48, Dan S. MacAbre wrote:
DICEGEORGE wrote:
glue/screw/nail an offcut to the outside / other side of the door.
drill new hole into that and through the door.
remove offcut

[g]

It might work if the offcut is at least as thick and strong as the
door being cut into, but the breakthrough into the asymmetric cut is
likely to be traumatic and difficult to control throwing the drill hard.

I was thinking of that after I posted. I'm not sure that the flat bits
I have will continue to go straight once they're in the hole, although
they do have flat sides, which I suppose will help, and then I just have
to hold it straight.

It is getting difficult to work out what you are trying to do. I
imagined a hole *through* a door for a handle but elsewhere it sounds
like you are talking about a blind hole into the door frame.

If there is a hole right the way through you could trace out the shape
and use a fret saw to cut the extra part out.

There are hybrid chunky drills that are midway between a twist drill
and a milling tool or a cone step drill which might just work if it is
long enough to be centred on scrap offcut nailed to the far side. Even
so you are going to get a kick off it every time the cutting side bites.

It does sound like the first thing I should try,
just to see how it goes. The wood (oak) is hard, which I think will
help to control things a bit.

Unfortunately it will make it incredibly difficult to control once you
have a cut into hard material on one side and no resistance at all on
the other probably flicking the drill out of your hands.


Sometimes that happens (and I have bent spade bits that way) but if you
are only looking for a small increase in diameter it is sometimes
possible. You feed the drill in vary gently when it is running fast, if
you are lucky it cuts a conical entry which follows the axis of the
original hole. Once you get a little way in, it becomes self centring.

I should also have said you need to have the door fixed fairly rigidly
so that it does not swing. Either with wedges underneath, or clamping in
place with a workmate.

On Friday, 26 May 2017 11:49:01 UTC+1, Dan S. MacAbre wrote:
DICEGEORGE wrote:
glue/screw/nail an offcut to the outside / other side of the door.
drill new hole into that and through the door.
remove offcut

[g]


I was thinking of that after I posted. I'm not sure that the flat bits
I have will continue to go straight once they're in the hole, although
they do have flat sides, which I suppose will help, and then I just have
to hold it straight. It does sound like the first thing I should try,
just to see how it goes. The wood (oak) is hard, which I think will
help to control things a bit.

doesn't work with a flat bit

On Friday, 26 May 2017 14:30:18 UTC+1, 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.

Ohh. then a blacksmith's drillbit.


NT

wrote:
On Friday, 26 May 2017 11:00:45 UTC+1, Dan S. MacAbre wrote:
tabbypurr wrote:
On Friday, 26 May 2017 10:27:57 UTC+1, 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.

A flat bit would go out of control. A spiral fluted bit close to the current hole size could be pushed sideways & cut, if not ideally. You might also get mileage out of those filing drill bits, but I bet a big fat spiral blacksmith's bit would be much better - and more expensive.

Yes, I only have flat bits, and I'm too scared to even contemplate
pushing one of those at the hole.

it would not go well

I like the look of those spiral
fluted bits, assuming that you mean those stepped conical things that my
first search has found?

no, I mean blacksmith's drill bits. Assuming you want to move the hole sideways. If you wanted to enlarge it all round the stepped things would almost do that.


No, it's not a moving the spindle hole sideways thing. I'm trying to
make to latch hole in the side of the door wider and deeper.

NT

newshound wrote:
On 5/26/2017 11:07 AM, Dan S. MacAbre wrote:
John Rumm 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.

If I am reading this right, the question is, basically can I "move" the
hole for the handles a bit further away from the edge of the door?
(either by simply making it larger, or by redrilling it but offset from
the current location)

e.g: http://wiki.diyfaq.org.uk/index.php/...ch_Fitting.jpg

moving that hole on the left a bit further to the left...

A few options...

You can re-drill a hole larger if you use a twist drill - basically the
existing hole will allow the bit to centre. That does not work with flat
spade bits or forstner bits though.

If you simply want a bit more space toward one side of the existing
hole, then a file or rasp would be a quick way to elongate the hole.

If you want to drill a hole offset from its current location, you could
as you suggested fill it and redrill. However a quicker option would be
to drill a hole the size you want into a bit of scrap wood (bit of 3/4"
inch ply or some 2x1 would do), align that hole on the door where you
want it, and then clamp the scrap to the door. Now drill though using
the hole in the scrap to guide the drill. Note that with things like
flat bits that will only guide the bit so far - once the full width of
the spade is no longer in the guide it will wander or snag. (you can
probably get the full depth of the door by applying the guide to both
sides and drilling from both sides). The technique works ok with auger
bits though.

Other options include mounting two hole saws on the same arbour. The
back one, the size of the hole you want, and the front one the size of
the existing hole.


Thanks for that, but it's the hole in the side of the door, I'm
looking at. The existing latch is tubular, and a snug fit in a 22mm
hole. All the replacement latches (of 83mm backset) that I can find
(I borrowed some from helpful local stores) are rectangular, and at
least 23mm high. Everything I see on eBay has a similar height. I
was just wondering if I could screw a piece of wood on the side, and
go through that, but I'm not sure what would happen once I'm in the
existing hole. It might start to drift to one side.


Ah, so when you say "side" you actually mean "edge"? Going up from 22 mm

Edge, yes. But then, I know nothing about doors :-) I wouldn't have
called the large flat bits the sides.

round to 25 mm round is actually just about possible with a flat (spade)
bit, particularly with a cordless drill which normally gives you a bit
more control than a mains one.

For the hole in the side (where you want to move the handle further in
from the edge) the quick and easy way is to turn the hole into a slot
using a "straight" saw bit in a multitool (3 cuts needed)

Okay, might be a good excuse to put a multitool on my birthday present
list. It's not far off :-)

wrote:
On Friday, 26 May 2017 14:30:18 UTC+1, 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.

Ohh. then a blacksmith's drillbit.


NT


Looks good. I hadn't imagined they made them so big.

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

On 26/05/2017 16:16, Dan S. MacAbre wrote:
The Natural Philosopher wrote:

A router with a 4" tool might work if such exists

But I think that the permagrits might actually do the job


I've long been curious, but have no idea how routers work, or even the
full extent what you can do with them. I've looked at them in shops,
and I've seen amazing things that have been made with them, but am not
mentally able to connect the two :-)

That's a fairly deep subject in itself! Youtube would probably be your
friend to get some examples of good router applications.

A router is one of the most versatile power tools in the workshop. It
will cut, shape, rebate and profile edges. Make joints, flatten
surfaces, plane edges, carve, letter, flute... the list goes on. Much of
the skill of using them is coming up with jigs to get them to do what
you need.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 27/05/2017 08:34, PeterC wrote:
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.

Augers tend to pull in due to the effect of the worm drive on the
front[1]. In this application that will be spinning in free space, and
so not having any effect.


[1] A common trick to "tame" an auger is to pre-drill with a smaller bit
such that you leave less or nothing for the worm to engage with.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sat, 27 May 2017 09:41:52 +0100, John Rumm wrote:

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.

Augers tend to pull in due to the effect of the worm drive on the
front[1]. In this application that will be spinning in free space, and
so not having any effect.

[1] A common trick to "tame" an auger is to pre-drill with a smaller bit
such that you leave less or nothing for the worm to engage with.

I was thinking of the cutting edges 'picking up' the wood, rather like a HSS
bit does on plastic. At work we had a few backed-off bits, but doing that to
a 25mm auger is a bit expensive for 1 hole.
--
Peter.
The gods will stay away
whilst religions hold sway

On Saturday, 27 May 2017 17:32:21 UTC+1, PeterC wrote:
On Sat, 27 May 2017 09:41:52 +0100, John Rumm wrote:

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.

Augers tend to pull in due to the effect of the worm drive on the
front[1]. In this application that will be spinning in free space, and
so not having any effect.

[1] A common trick to "tame" an auger is to pre-drill with a smaller bit
such that you leave less or nothing for the worm to engage with.

I was thinking of the cutting edges 'picking up' the wood, rather like a HSS
bit does on plastic. At work we had a few backed-off bits, but doing that to
a 25mm auger is a bit expensive for 1 hole.

FWIW Bosch multiwotsits are already backed off, no alteration needed. It helps them survive the masonry busting action better.


NT

On 5/27/2017 9:37 AM, John Rumm wrote:
On 26/05/2017 16:16, Dan S. MacAbre wrote:
The Natural Philosopher wrote:

A router with a 4" tool might work if such exists

But I think that the permagrits might actually do the job


I've long been curious, but have no idea how routers work, or even the
full extent what you can do with them. I've looked at them in shops,
and I've seen amazing things that have been made with them, but am not
mentally able to connect the two :-)

That's a fairly deep subject in itself! Youtube would probably be your
friend to get some examples of good router applications.

A router is one of the most versatile power tools in the workshop. It
will cut, shape, rebate and profile edges. Make joints, flatten
surfaces, plane edges, carve, letter, flute... the list goes on. Much of
the skill of using them is coming up with jigs to get them to do what
you need.


Agreed. A lot of skill and experience needed to do the harder stuff
well. Also the tool which inflicts irreversible damage on a workpiece
(or even the user) faster than anything else.

On 26/05/2017 23:07, Dan S. MacAbre wrote:
wrote:
On Friday, 26 May 2017 14:30:18 UTC+1, 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.

Ohh. then a blacksmith's drillbit.


NT


Looks good. I hadn't imagined they made them so big.

They are quite pricey though usually!

(last time I needed to do what you are describing, I went low tech an
used a chisel)

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sat, 27 May 2017 10:17:35 -0700 (PDT), wrote:

On Saturday, 27 May 2017 17:32:21 UTC+1, PeterC wrote:
On Sat, 27 May 2017 09:41:52 +0100, John Rumm wrote:

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.

Augers tend to pull in due to the effect of the worm drive on the
front[1]. In this application that will be spinning in free space, and
so not having any effect.

[1] A common trick to "tame" an auger is to pre-drill with a smaller bit
such that you leave less or nothing for the worm to engage with.

I was thinking of the cutting edges 'picking up' the wood, rather like a HSS
bit does on plastic. At work we had a few backed-off bits, but doing that to
a 25mm auger is a bit expensive for 1 hole.

FWIW Bosch multiwotsits are already backed off, no alteration needed. It helps them survive the masonry busting action better.

NT

That sort of comes back to what I was saying about using a masonary bit; I
doubt if Bosch Multimaterial bits are available in 25mm (ICBA to check).
I'd guess that most of us go up to 25mm masonary bits. With care, an SDS bit
will be OK in an ordinary chuck with very little throw - might get ½mm extra
on diameter that way.
--
Peter.
The gods will stay away
whilst religions hold sway

On Sat, 27 May 2017 09:41:52 +0100, John Rumm wrote:

On 27/05/2017 08:34, PeterC wrote:
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.

Augers tend to pull in due to the effect of the worm drive on the
front[1]. In this application that will be spinning in free space, and
so not having any effect.


[1] A common trick to "tame" an auger is to pre-drill with a smaller bit
such that you leave less or nothing for the worm to engage with.


A common trick, for me, in this sort of situation is to spin a holesaw
counter clockwise, until it's worn a groove, and then spin it clockwise.
With perhaps a little filing first, to establish a centre.

You don't get the aggressive bite in the reverse direction.