What lubricant do I need to drill porcelain slabs?

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uptown47

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Hi all,

I've got 600x600x20mm porcelain slabs in my garden. I need to drill 3 x 12mm holes in some of them to fix a balustrade to.

I bought an Erbauer Diamond Tile Drill Bit (12mm) from Screwfix and I've just done a test cut - which went really well (see photo).

IMG_20220720_115142.jpg

I'm using a piece of wood to steady the bit until it gets cut into the tile.

The 'bit' came with some waxy stuff inside it which melted as it cut and (I presume) provided the necessary lubrication.

For drilling the rest of the slabs - what would you advise that I use for lubrication? Can I just use water (if so, hot or cold??) or do I need some sort of cutting fluid or something else??

I know to go steady with the bit and just use a medium pressure but, also, any other tips on drilling the slabs would be most helpful.

Thanks :-)
 
opps said:
The wax inside the bit should be sufficient.
Click to expand...

It won't be sufficient for the amount of holes I need to drill. It's mostly gone and that's just one hole.

Do you know if there's anything else that's suitable? Or can I buy more of the wax?

Thanks
 
uptown47 said:
It won't be sufficient for the amount of holes I need to drill. It's mostly gone and that's just one hole.

Do you know if there's anything else that's suitable? Or can I buy more of the wax?

Thanks
Click to expand...

Wow. There should be enough wax to drill dozens of holes.

Anywho, water will be fine. Some people use bluetack to create a well which they fill with water.
 
opps said:
Wow. There should be enough wax to drill dozens of holes.

Anywho, water will be fine. Some people use bluetack to create a well which they fill with water.
Click to expand...

That's a great idea with the bluetack.

I'm glad water will be sufficient.

Just a side question (as you seem to know what you're talking about) - is there an easy way to tell when the bit will need changing? I've got about 40 holes to drill. I'm not sure what sort of life expectancy these bits give?

Is it just a case of judging when it's not really cutting anymore? Or is there a visual check?

Is 40 holes nothing to this type of 'bit'? Or would I be expected to only get 10 or 20 holes out of it?

Thanks :-)
 
diamond bit best lubricant is water, but anything with a low viscosity will do. You could always use a diamond impregnated lapping stone to dress the edges if the corners are too blunt and you just have a few more holes to do?
 
Thanks Mike. Yep, I've been using white tack, rolled into a sausage and wrapped around the hole to make a bund, then regularly topped up with water as I drill. I'm managing about 12 - 15 holes per drill bit. Slow going. Spent most of the weekend on it and only managed 30 holes so far until rain stopped play. Only 15 more holes to go.... :-)
 
the other thing is that diamond bits like higher speed and lower pressure to last longer and make progress.
 
Mike13 said:
the other thing is that diamond bits like higher speed and lower pressure to last longer and make progress.
Click to expand...
Thanks for that. Wish I'd known that before I started :) I've been going slow but with some pressure. Not letting it get hot. I was under the impression that you shouldn't let them get so hot that they couldn't comfortably be touched?

So, should I be going fast and light pressure?

I've done 30 holes so far. And I've got 15 more to do - although can't do them yet as I need some other work completing before I can drill those.

Thanks :)
 
Well the PCD drill I used many years ago does not correspond to this use case. it was 12 1/4 " diameter at about 100rpm, and about 4 tonnes pressure on the bit, so about 5 x speed of carbide bit and about 1/5 the weight on bit.
 
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