8mm diamond drill bit recommendations sought

[RogerS]

Can anyone please point me in the direction of a decent make?

Not like the utterly useless and waste of money one from Toolstation. You know, the one that wears out after one hole (wet cut) and even if it hadn't worn out, the hole down the middle is full of the remains of the first hole and there is no way of extracting it. Use once which at £16 a pop is daylight robbery.

 

[Eric the Viking]

I can't recommend a decent make any more (Marcrist used to be quite good, years ago), but they used to proliferate on eBay at low prices. Regarding extracting the waste, I push it out by tapping the head of a masonry pin (i.e. facing backwards) towards the back end of the drill (not pushing it back from whence it came). It usually works.

You can also use them dry on tiles, once you've cut through the glaze - it makes them slghtly less gummy and easier to clean out. The water lube thing isn't a big deal. I have several of the bigger sizes for doing masonry for plumbing pipes and extractor ducts. I've never used water lubrication with those, although they do get quite hot. Also, if it's dry you can vacuum out the dust little-and-often, which is way better than trying to power through the entire cut in one go.

They're not my favourite tool, but they an be made to work reasonably well.

 

[RogerS]

I’m not sure what you mean re tapping it out. My drill bit isn’t hollow all the way through

 

[Jonathan]

What you drilling?

 

[AJB Temple]

Rog, there are a number on Amazon which are diamond drill bit sets for under £20, that release a wax lubricant as you drill. All much of a muchness but you can get the sets with several of the same size for that price, as well as a pointed glass bit. I recently bought some to drill through very hard glazed porcelain, where a normal masonry bit made no impression. Two holes nowhere near wore out the only bit I used (of 5 in the set). I did rest the bit and rinse under a cold tap every 20 seconds, just to cool it down and clear the dust. A

 

[Distinterior]

Even though some of these diamond drill bits state they can be used dry, I always try to use them wet whenever I can, as it keeps the temperature and dust down to a minimum.

I have a Japanese set that I bought back in 2000, that came with it's own mandrel with a water feed and the drill bits themselves had to be bought separately, depending on the diameter required.....
The mandrel shaft that the bits screw onto is hollow, as are the bits themselves, to allow for the flow of water from a pump-up pressure container.
It works a treat, but you do get a little "plug" occasionally inside the drill bit hole, as mentioned by @Eric the Viking .
I remember it cost me an eyewatering amount back then.

If I didn't have it and I needed small diamond drill bits today, I would probably plump for Marcrist bits.....
I have quite a few of their larger diamond core drill bits for various sized plumbing pipework & ducting and they are well made and seem to have a long life.....My 150mm dia core bit is 27 years old now and cost me £150, but it's still got plenty of life left in it yet....
Where have all those years gone though...?

 

[RogerS]

What you drilling?

Porcelain tiles

 

[RogerS]

I took back the drill bit I got from Toolstation which had worn out after one hole. Brand = Minotaur. Total rubbish.

Bought two Erbauer from Screwfix and cut the first hole - wet. The one 'good idea' I had was to pull the drill bit out of the hole and break off the 5-6mm tile stub. That way it lessened the likelihood of blocking the bit. Repeated after another 5mm or so. By doing that all that was left inside the drill bit was easily scraped ot with a screwdriver.

Mind you those Japanese that Tim had are definitely droolable

 

[Lurker]

Rog, there are a number on Amazon which are diamond drill bit sets for under £20, that release a wax lubricant as you drill. All much of a muchness but you can get the sets with several of the same size for that price, as well as a pointed glass bit. I recently bought some to drill through very hard glazed porcelain, where a normal masonry bit made no impression. Two holes nowhere near wore out the only bit I used (of 5 in the set). I did rest the bit and rinse under a cold tap every 20 seconds, just to cool it down and clear the dust. A

I have had a similar experience. Bought a cheap set to drill one hole expecting nothing more. Found them good enough to keep for future jobs.

 

[Jonathan]

Porcelain tiles

Porcelain tiles are sometimes difficult and Porcelanosa porcelain is the worst especially when it’s thick. I had good luck with a special tungsten carbide bit designed for porcelain. Secret I found was keep the speed down super slow.
Unfortunately can’t find a link to the bits I used, but remember they were very expensive and cut very quickly. When the cutting edge had gone they were useless in porcelain but I used them for years later in masonry.
Also seen plumbers use a masonry nail to punch through thick porcelain tiles, believe it or not it works…. natural it has breakout on the back of the tile.

 

[Distinterior]

The reason I bought my Japanese set back then,.....The client had purchased her own porcelain wall & floor tiles for her bathroom and paid an arm & leg for them....( porcelain tiles were nowhere near as common back then as they are now).I tried about 10 different masonry bits from various manufacturers, all of which were brand new to drill the tiles, which were about 10 or 12mm thick from memory......Every bit either melted of went blunt in next to no time.

I finally contacted the tile supplier and asked them what they recommended to drill their tiles and they told me about the Japanese drill attachment.
I needed to buy 6mm, 8mm, 10mm, 12mm and 14mm bits coz there was a shower cubicle, wall hung basin with a semi pedestal, large wall hung towel radiator, illuminated mirror, toilet roll holder, etc,etc, ....All the fixings were a different size.....

One small consolation that came about from buying the set,....The tile supplier contacted me on about 4 occasions in the following year or so, asking if I could go and drill holes for some of their other customers that had bought the same tiles.....It certainly helped to recoup some of the initial financial outlay

 

[AndyP]

The best masonry core drills I have used were Armeg, made in the UK too.

Armeg UK | Power Tool Drilling Accessories

Armeg designs and manufactures performance-quality power tool drilling accessories, for the ultimate in control and confidence. Visit Armeg's website for more.

armeg.com

I’ve not used anything as small as 8mm though but these have done through at least half a dozen walls.