Enlarge a hole in wood?

[Dan S. MacAbre]

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.

[tabbypurr]

A flat bit would go out of control. A spiral fluted bit close to the curren t 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 blac ksmith's bit would be much better - and more expensive.

NT

[John Rumm]

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:

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.

[Dan S. MacAbre]

Yes, I only have flat bits, and I'm too scared to even contemplate pushing one of those at the hole. I like the look of those spiral fluted bits, assuming that you mean those stepped conical things that my first search has found?

[Dave Plowman (News)]

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.

[Dan S. MacAbre]

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.

[Bob Minchin]

A power tool is not always the answer.Use a half round rasp.

[Dan S. MacAbre]

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

[Dan S. MacAbre]

Okay, thanks. I do have one somewhere, but it's quite a hard door, and the hole will have to be made deeper than it currently is. Maybe once I've started it off with a rasp, then I can cut it deeper with the bit.

[DICEGEORGE]

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]

[Dan S. MacAbre]

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.

[Roger Hayter]

I did exactly the same job with one of the wood auger bits like the second type on this page:

I started by filing the entrance to the hole so I could ge the first couple of millimeters of the bit centralised, and turned it a few turns using a strap wrench on the chuck before cautiously finishing with the low speed on the power drill. It was still hard to keep it central, but I'm useless at carpentry so it must be reasonably possible.

[Dan S. MacAbre]

I think that would be easier to keep central than the flat things I have. Means buying more stuff, though, which is starting to worry me these days. I have too much stuff that I only bought for one job. Of course, I will have more doors to do. OTOH, I thought that about all the other stuff I bought, too :-)

[Martin Brown]

A half round rasp and some elbow grease should get it then.

[Andy Burns]

I would tend to go with the auger, rather than the quad-flute someone else mentioned, I find the letter *very* aggressive so they have their place for drilling joists etc; but where the workpiece isn't held firmly, or where the bit can wander, things can go wrong very quickly with them ...

[The Natural Philosopher]

Step drill? E.g.

[Dan S. MacAbre]

I have one somewhere. It could at least start the hole if nothing else.

[charles]

Or even, a round Surform.

[Dan S. MacAbre]

If I can find one that goes up to 25mm (or even an inch :-)),which is what I will need for this job, it might be a useful thing to have around for other things, too.

[Martin Brown]

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.

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.

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.

This is one example where the right hand tool will beat power tools.