Drilling partially overlapping holes

[GMM]

I need to change a couple of night latches. I bought a 60mm backset one to replace a 60mm latch and guess what? they're just a bit different. I also have a door that has a 40mm backset but can't easily be opened and could use a 60 instead. So the problem, in each case, is how to drill a hole off centre from the previous one.

In the first case, I could probably enlarge the hole on one side with a rasp. Not very elegant, but it would all be covered by the fittings. For the other, the point of a spade drill would be boring into fresh timber, but it will probably not like clunking against the old hole as it turns.

So does anyone have a tried and trusted solution to this situation? I have thought of using a two-part filler to fill the old hole then treating the whole thing as new. Alternatively, clamping some timber to the face of the door and drilling through that first to constrain deflection of the drill. Would a Forstner bit be any help for this? (never used one but they look like they might)

I'm sure I can't be the first person to have this problem, so any (sensible) suggestions gratefully received.

Cheers

[The Natural Philosopher]

fill old holes with car body filler.

[John Rumm]

That is not too bad if the new hole is mostly contained, however there is risk of it splitting out if you have not got much wood around the point of the spade.

Cutting a wood plug (square with the corners whittled off can be good enoug) to fit the old hole can work.

This technique works best with a hole saw I find. Its relatively easy to constrain them when drilling part wood and part nothing.

The decorating details I used on this book case were done with a holesaw in a pillar drill - however the ply template would do just as well (in fact probably better than on my cheap and sloppy pillar drill!)

[NT]

Do yourself a favour and get a latch that fits. Lot easier than plugging and redrilling, and filling.

NT

[Reentrant]

A Forstner bit wouldn't mind - ideal for overlapping holes.

[dennis]

Its easy despite what people say.

Clamp a scrap block of wood to the door, drill trough it. Its easier with a hole saw or a forsner bit as they are guided by the hole once started.

However if you don't fill the hole the door will be weakened some more.

[GMM]

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Excellent advice as ever, Mr Rumm - the only tool I didn't think of was a hole saw but now you raise it, it's clearly the best thing, as a piece of ply or something would effectively keep it in position, along with the pilot/arbour, where there's some wood in the centre.

[GMM]

Kinda hard to get a 60mm backset that fits the same as a 40mm one, since the whole point is to bring the thing away from the frame as much as possible. I can't imagine what the person who fitted the 40mm set there was thinking, as the door is set behind brick on our sideway. Having sued the wrong size, he then spaced the whole thing back (so it could be opened from outside) by an inch or so, so the door always looks like it's partway open.

So far as the other one is concerned, it seems that a BS marked security lock is just different enough from an old low security latch as to not line up. If I put a non-BS one on there, it wouldn't really be worth bothering to change it.....

[GMM]

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Just to complete this thread - in case anyone ever finds it (!)

I formed the hole using a hole saw (set up with the template from the lock packaging) in 9mm MDF, then clamped that to the door and put the hole saw through, with its pilot drill in fresh air. The MDF guided the saw and I was through in seconds (with a pause to do the last bit from the other side. Nice clean hole, smack in the right place.

The only gotcha is alignment - it was trickier than I anticipated ensuring I was in line vertically with the old hole, as it had been hacked out rather than drilled. I did take the precaution of drawing vertical and horizontal lines to the hole centre before I cut the MDF, which helped, a bit.

Of course, fitting the latch onto the tab from the lock that sticks through the door took a bit of swearing (and a bit of filing) but then I find it always does, before slipping in as though there was never any problem.....

Thanks for all advice!

[Rick Hughes]

On 22/06/2012 00:25, GMM wrote: Alternatively, clamping some timber

Forstner bit is OK ... but I would not wan to use one of those outside of a drill press.

I would clamp on a piece of wood to give you a new face and then use a hole saw, take your time, very light pressure