Drilling a small hole in thick porcelain.

Wanted: an 1/8 inch or so hole in the porcelain of a bog cistern. I've used this tile-hole cutter drill-bit on tiles before with no problems. But on cistern porcelain got through the glaze ok but no further in than about 1/8 inch deep. I've not tried sharpening as it doesn't seem blunt and I've tried oil, then, water as cutting medium but no further in. Anyone been here before ? Correct drill speed ?
Seemed a neat idea for making a 2-level flush from an old simple flush mechanism. Pass a brass rod through the cuistern lid , located onto the ball of the float valve. Then add a weight to the brass to depress the float more, for more water, until the excess weight is balanced off. Remove the weight for cheap-skate flush.
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But you'd have to wait for it to fill for a full flush, wouldn't you?
One simple dual-flush mechanism works by having a 'syphon breaker' hole in the side of the syphon, which is obstructed by the flush valve if you hold onto the handle.
Have you considered doing something like that, which would only require drilling a hole in the side of the syphon?
W
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Drilling porcelain is addressed in the DIY FAQ http://www.internode.co.uk/diyfaq/drillfaq.htm
But on this usenet group I posed the same question (4 Aug 2005 16:02:47 +0100) and was recommended to use an ultrasonic drilling machine. It's like an pillar drill SDS but with the bit driven at multi-khz frequencies and plenty high impact force. See: http://www.sonicmill.com/machine.asp
I am presently seeking inspiration as to how to track down a local machine shop with one of these useful machines. I tried glass/masonry companies but drew a blank.
Let me know how yo get on.
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problems.
I made a dam from blue-tac and made a crude drill bit from the shank of an old HSS drill bit. Grinding two flats on the shank end to make a sort of screwdriver blade. Repeated sharpening 3 or 4 times. With this got down to about 1/4 inch but then got concerned about breakout on the inside. This cover is hollow on the edges so presumably made by all angle rotation of slip/paste in a mould. I doubt if the central area is hollow though. Tried firstly finding the internal matching point by putting some bits of magnet in the hole and tracing with iron filings but didn't work convincingly. Then thought I'd try a Megger and presumably because of the dam of water it gave a resistance trace so could find minimum position. Could even use a 30 Meg ohm DVM as order 10 to 20 Meg ohms. I will continiue tomorrow as I don't know how thick the central area is .
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than
Worked a treat.
Found a small rod magnet and waving that about the outside hole gave a very clear indication in the iron fillings on the inside. With successively smaller "lollypop" grind stones in a hand drill gradually zeroed in from the inside. Thickness about 10mm.
A tennis ball (if dislodged won't smash things) ,made a small hole and a cut into it to load inside with bits of lead. Glued a locator/protector to the ball valve to take the end of the bit of brazing rod. Cut a slot in a wooden wedge and for a refinement added a 'crapometer' scale to the top surface of the wedge. Now just a matter of working out a self return mechanism to the wedge to take it back to the minimum flush setting.
Ah DIY
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net /
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Peter wrote:

www.orc.soton.ac.uk have got one!
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