Drilling china ?

[robgraham]

Our daughter has given us a 250mm dia china wall clock which has the hands of grandchild No 1 impressed into it.

The quartz clock mechanism was clearly the cheapest the potter could find - noisy and the hands slip on the shafts. I've bought in a German made replacement but find that it uses a sleeve nut instead of a plain nut for mounting (nothing in the advert about this) which requires a 10 mm clearance hole instead of the 8 mm one in the plate.

What chances are there of a 10m tile drill opening up this 8mm hole (plate is 7mm thick) successfully ?

Thanks Rob

[newshound]

Presumably it is glazed? Since you don't require much increase in diameter, I think I might start with a needle file set, try to get through the glaze and then see if the bulk material is relatively soft.

If you have a dremel type tool you could try an undersized abrasive or diamond coated tool. The risk of enlarging with a drill is starting off OK but then ending up putting tensile loads on the plate as it goes in.

[polygonum]

My guess? Not a hope in hell. As soon as a drill starts to bite, at all, it will crack it. At least that is what I'd expect. "Pottery" tends not to be as structurally sound and homogeneous as commercial ceramics - and they can be difficult.

You might manage to grind it out to size using some form of abrasive.

[John Rumm]

Has grandchild got a big hand and a small hand then? ;-)

Is it actually china, or just pottery? The former it much harder to drill - a dremmel type tool with an abrasive burr on it might be safest.

[robgraham]

Thanks guys - good points; and yes the Dremel is the better option.

Rob

[Gazz]

Nooooo, Jeremy Beadle's been re-incarnated,

[Dave Liquorice]

Is this china as in bone or just pottery? China is translucent, pottery opaque. China is damn hard, pottery relatively soft.

"Impressed" as in shoved into soft clay of newly produced plate, left to dry, glazed and fired?

There won't be much plate left after a 10m drill has been at it. B-)

7mm thick also sounds more like pottery than china.

A sharp flat and pointed tile drill should be OK in pottery. The problem will be centering it properly in possibly a no longer absolutely circular hole(*) and holding the drill firm and square. Think I'd be tempted to use the pillar drill on it's highest speed, center up by very slowly lowering the bit into the hole with the plate only loosely held. The glaze may shatter away take it slowly... Once centered, clamp the plate some how. Drill very slowly with goodly amounts of water. As with all tools let it do the work...

(*) No doubt the hole was made before fireing so shrinkage of the clay during fireing will have distorted things.

[Dave Baker]

Slim to none. As the drill bit breaks out through the far side of the hole it'll probably bust chips off and make a bit of a mess. Drilling part way in from both sides would be better but if it's just soft pottery a round file ought to do it. Hard glazed china might require a diamond file or careful work with a carbide bit or a stone in a Dremel.

[meow2222]

A tile drill bit needs material to centre it, and even then is very prone to severe vibration. They also must be used fast & gentle, IME slowing them down tens to make them de-centre and vibrate badly.

As said, I'd use an abrasive, and go gently.

NT

[AC]

What ever advice you follow, get an old plate or what ever seems most similar and try it out first.

[The Natural Philosopher]

Ive drilled all sorts of stone and ceramic tiles with a diamond tipped core drill - very cheap. It will wander: the best technique is to hold it very firmly and apply very light pressure. It then cuts a circular groove and seats itself.

[Andy Dingley]

Pretty good, but then I'd be using a pillar drill to do it. Rigidity is important here, especially if you don't have a centre point to locate the drill.

Get yourself down to a local charity shop and buy a couple of ugly plates with kittens on. Then practice.

If it isn't working, then go for the Dremel option. If the ceramic is softish (almost certainly), then this would be easy and (more importantly) lower risk.

[Chris Hogg]

Use a tapered/pointed grinding stone such as one of the ones shown here:

from both sides alternately and take it slowly.

[Owain]

I think I'd take the cowardly way out and get a clock movement that will fit the existing hole.

Presumably this piece has sentimental value and/or isnear- irreplaceable? (grandchild's hands will have grown)

Owain

[Grimly Curmudgeon]

One of the arrow-shaped glass drills would do the job perfectly.

[robgraham]

Hi everyone - many thanks indeed for all your suggestions. I have one of the Dremel like tools but tend to forget it is there ! It did indeed do the job cleanly and without trauma with a suitable shaped grinder bit. The hole is now a clean 10mm diameter.

Rob

[polygonum]

Pleased to hear that!

[newshound]

Good result!

[GB]

On 04/11/2012 14:11, Owain wrote:> On Nov 3, 10:22 pm, robgraham wrote: >> Our daughter has given us a 250mm dia china wall clock which has the >> hands of grandchild No 1 impressed into it. >

I agree. Return the other one under DSR.

Take a plaster of paris cast of the hand imprint before starting? :)

[Dave Liquorice]

But be careful. Setting "plaster of paris" is exothermic. By the time you realise this it's set too hard for you to get your hands out and it can get hot enough to burn...