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Old 27th Oct 2022, 7:16 pm   #1
Al (astral highway)
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Question Cutting porcelain?

Mods, not sure where to put this so please move if you want.

I need a reliable way to cut a porcelain?? tube for a homebrew RF project . Any tips appreciated.

I’ve tried all the cutting tools available to me but they just skitter off the glassy surface and Also applying mechanical shock but no success and ragged fracture of a trial piece.

It’s white porcelain, about 1cm dia and hollow

Thanks folks
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Old 27th Oct 2022, 7:20 pm   #2
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Default Re: Cutting porcelain?

How about an electric circular tile saw, water cooled/lubricated diamond wheel ? Someone you know prob has one.
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Old 27th Oct 2022, 7:28 pm   #3
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Default Re: Cutting porcelain?

That would be ideal but I don’t know anyone with one. Really hoping for something I might have overlooked with what I have, before I ditch the idea for another material.

Thanks though
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Old 27th Oct 2022, 7:43 pm   #4
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Default Re: Cutting porcelain?

Quote:
Originally Posted by Al (astral highway) View Post
I’ve tried all the cutting tools available to me but they just skitter off the glassy surface...
When drilling, I use PVC tape to stop the drill bit from sliding. It may also have the same effect when cutting, though I've never tried it.
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Old 27th Oct 2022, 7:51 pm   #5
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Default Re: Cutting porcelain?

Welcome back Al, nice to hear from you after the break!

I've done a fair bit of stained glass cutting and I'd recommend you try a simple glass cutter, perhaps lubricated with oil.

Push the tube against a piece of right-angled aluminium with your free hand whilst gently pressing the lubricated glass cutter at the desired length and rotate. With a confident pressure, place your thumbs either side of the score mark and press.

If the desired length is very short, use a piece of cloth in some pliers.

The whole thing takes a lot less time than it took me to type this!

You can do this!
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Old 27th Oct 2022, 9:36 pm   #6
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Default Re: Cutting porcelain?

A diamond cutting wheel in a basic Dremel-like tool should do it if you're careful and persistent.

All ceramics are basically glass.
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Old 27th Oct 2022, 9:47 pm   #7
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Default Re: Cutting porcelain?

Pipe-cutter to make a score mark, then snap as Kentode says? There are diamond-covered wire 'blades' available that go in a fretsaw frame. I got some from the local hardware shop, so they can't be very peculiar. I believe they're for cutting tiles; as Paul says they're all much the same sort of thing.
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Old 28th Oct 2022, 8:31 am   #8
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Default Re: Cutting porcelain?

Quote:
Originally Posted by Kentode View Post
Welcome back Al, nice to hear from you after the break!

Push the tube against a piece of right-angled aluminium with your free hand whilst gently pressing the lubricated glass cutter at the desired length and rotate. With a confident pressure, place your thumbs either side of the score mark and press

You can do this!
Nice to be back too, Ken!

I’ll try this out over the next few days!

Thanks also to Dave, Paul and Uncle Bulgaria.
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Old 28th Oct 2022, 10:48 am   #9
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Default Re: Cutting porcelain?

Some types of cerammics are so hard that diamond is going to be the only thing that works. For years I have managed to drill holes in glass and ceramic tiles using a masonry drill, rotated slowly in an oil bath and using high pressure, but trying this on the off cuts of the porcelain tiles left over from our shower, proved futile. The builders had used diamond drills to drill holes for fixings, and I soon found out why.
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Old 28th Oct 2022, 4:57 pm   #10
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Default Re: Cutting porcelain?

I had a similar problem when cutting a broken terracotta garden planter a few months back. I eventually tried using the angle grinder, but that just led to overheating so I dumped the planter in the end. Ceramics are difficult to cut considering their fragility.
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Old 28th Oct 2022, 6:51 pm   #11
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Default Re: Cutting porcelain?

I wonder if this would work (it usually does on glass) - wind string around it, meths on string, light it for several seconds, then drop into cold water to create a crack.
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Old 29th Oct 2022, 10:30 am   #12
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Default Re: Cutting porcelain?

That sounds like it’s worth a try! Great suggestion! I’ll give it a whirl and report back.
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Old 29th Oct 2022, 11:32 am   #13
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Default Re: Cutting porcelain?

There was a TV programme a few months ago showing how porcelain was traditionally made. The guy took a freshly-made porcelain cup out of the furnace and, while it was still glowing red hot, dropped it into a bucket of cold water, from which it emerged undamaged. Apparently that was the old test for quality.

Last edited by emeritus; 29th Oct 2022 at 11:34 am. Reason: typo
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Old 29th Oct 2022, 1:25 pm   #14
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Default Re: Cutting porcelain?

I wonder if you could perhaps use the method employed in backstreet CRT regunning shops to neck a tube?

Wind and few turns of thick bare copper wire round where you want the cut then connect the ends to a car battery using a couple of jump leads until the wire glows red hot.
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Old 29th Oct 2022, 2:49 pm   #15
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Default Re: Cutting porcelain?

A high-speed mini drill ("dremel") with a slitting wheel def the way to go. The ordinary slitting wheels are cheap as chips, so it may take one or two but...

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Old 29th Oct 2022, 7:29 pm   #16
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Default Re: Cutting porcelain?

You are looking at cutting a material that is both hard and tough.

There will be different grades of hard, but often ceramics of this type are used because of how hard they are and can resist wear. So cutting with an abrasive should be feasible, but you will need a hard abrasive. As suggested, diamond ought to do the trick, you might be on a hiding to nothing with anything less hard. I'd be trying with my diamond blade water cooled tile cutter (which is bordeing vintage and has a picture of Tommy Walsh on the box).

Now on to tough. Lots of suggestions of treating it like glass, but glass is not tough. Glass is brittle so most of the suggestions rely on the thermal shock to crack the brittle material. Porcelain was a favourite for teacups and teapots for a reason. Pour in hot tea and it doesn't break because of thermal shock. So I can't see the method for glass working.

BTW apparently the reason for 'milk in first' when pouring tea, was to protect poorer quality cups from the thermal shock, and nothing to do with taste.
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Old 29th Oct 2022, 9:54 pm   #17
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Default Re: Cutting porcelain?

Isn't an old spark plug a good item to practice on? I'm sure I've seen YouTube vids in which people cut and used spark plug ceramics as the nozzle for DIY grit blasters.

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Old 30th Oct 2022, 1:35 pm   #18
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Default Re: Cutting porcelain?

I realise it not quite the same but the only reliable way I’ve found to cut porcelain tiles is with a angle grinder with suitable disc or for finer trims a wet tile cutter.
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Old 30th Oct 2022, 6:00 pm   #19
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Default Re: Cutting porcelain?

It's just occurred to me that two of my crown's (molars) are porcelain. Where's Nickthedentist when you need him?

If l was Al I'd be putting the tube in my pocket next time I went for a checkup.
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Old 30th Oct 2022, 6:07 pm   #20
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Default Re: Cutting porcelain?

My dentist (located quite close to Silverstone) tells me he's done a job with his drill/accessories for a F1 team.

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