Best approach for drilling 20mm terrazzo tile?

[markharro]

We will shortly be needing to drill holes for some screws through our tiled shower enclosure. Mainly to instal two of these hinges - https://www.wholesaleglasscompany.co.uk/shop/colcom-8501n-glass-to-wall-shower-door-hinge.html - for a glass door.

 

Behind the tiles is 12mm cement board and behind that an 18mm ply pattress. 

 

Couple of questions - 

 

1 What is the best type of drill bit for the terrazzo and any tips to ensure that a clean hole is drilled?

 

2 I have 32mm of depth before the screws will hit the ply. The idea is to use long enough screws to penetrate the full extent of the 18mm ply. I was planning to use a drill bit of the same diameter as the screw I use. If it wasn't for the ply I would have to use rawlplugs but given I have ply I dont think I need these? 

 

 

[nod]

A 20 mil diamond hole bit and plenty of water will go through like butter 

[markharro]

Sorry I meant a 20mm thick tile, not the diameter of the whole which will probably be 6-8mm or the likes.

[nod]

22 minutes ago, markharro said:

Sorry I meant a 20mm thick tile, not the diameter of the whole which will probably be 6-8mm or the likes.

Same answer 

The diamond hole saws go down to 4 mil Drill slowwwwly Lots of water Most of the tile shops will sell drilling reservoirs That simply stick to the tile and cool the bit 

[Nickfromwales]

1 hour ago, nod said:

Same answer 

The diamond hole saws go down to 4 mil Drill slowwwwly Lots of water Most of the tile shops will sell drilling reservoirs That simply stick to the tile and cool the bit 

+1

 

https://www.amazon.co.uk/RUBI-4927-Easygres-Accessories-Metallic/dp/B00A3SDNK8/ref=asc_df_B00A3SDNK8?mcid=974bd86e521831afbdb57ac519b0afc3&th=1&psc=1&hvocijid=14815439965987008970-B00A3SDNK8-&hvexpln=74&tag=googshopuk-21&linkCode=df0&hvadid=696285193871&hvpos=&hvnetw=g&hvrand=14815439965987008970&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9046619&hvtargid=pla-2281435176618&psc=1&gad_source=1

[Nickfromwales]

When you get through the tile you need to poke back through the drill bit to get the pellet of tile out, before drilling the next hole.

 

When you get through the tile, stop. 
 

You can screw through the backer board and the ply for additional purchase. 

 

Also you must put a short bead of clear CT1 across the junction of the tray / wall, where the profile for the glass will be; just literally the width of it.
 

You then run a line of same up the back of the profile, from that bead, and bring it all together whilst all wet. You also want to fill the screw holes with it too. 
 

Then fix with the screws, and simply remove any excess CT1 with cheap baby wipes, lots and lots of them changed after one or two ‘wipes’.

 

You wipe the first short bead away almost completely after installing the profile, leaving the tile / tray junction to then take the cosmetic silicone work. 

 

If you miss the 1st step above it will leak. 

[markharro]

Thanks both - when you say a diamond hole saw do you mean something like this with a flat head - https://www.screwfix.com/p/erbauer-hex-shank-diamond-tile-drill-bit-6mm-x-67mm/51908

 

If so would I not need something like this to stop it skating all over the tile - https://www.screwfix.com/p/erbauer-diamond-tile-drill-guide/84524 ?

 

I was thinking of this sort of thing - https://www.screwfix.com/p/bosch-expert-hex-9-hard-ceramic-tile-drill-bit-set-5-pieces/974rr

 

And @Nickfromwales thats useful waterproofing tips but I think you are imagining we are using some sort of frame or metal profile- we are not. The idea is a single pane of glass pivoting on the 2 hinges and totally frameless. The room is a semi-wet room. So I guess the CT1 in the screwholes may be all we need?

[Nickfromwales]

6 minutes ago, markharro said:

Thanks both - when you say a diamond hole saw do you mean something like this with a flat head - https://www.screwfix.com/p/erbauer-hex-shank-diamond-tile-drill-bit-6mm-x-67mm/51908

 

If so would I not need something like this to stop it skating all over the tile - https://www.screwfix.com/p/erbauer-diamond-tile-drill-guide/84524 ?

 

I was thinking of this sort of thing - https://www.screwfix.com/p/bosch-expert-hex-9-hard-ceramic-tile-drill-bit-set-5-pieces/974rr

 

And @Nickfromwales thats useful waterproofing tips but I think you are imagining we are using some sort of frame or metal profile- we are not. The idea is a single pane of glass pivoting on the 2 hinges and totally frameless. The room is a semi-wet room. So I guess the CT1 in the screwholes may be all we need?

Use the Rubi one I linked to? It is a guide and waters the bit as you’re drilling? If you buy the one from SFx you’ll need a hand held water bottle to keep spraying it with. 
 

Yes to screw holes only, 👌

[Nickfromwales]

Most good tile shops stock the wet kits btw. 

[Nickfromwales]

10 minutes ago, markharro said:

Thanks both - when you say a diamond hole saw do you mean something like this with a flat head - https://www.screwfix.com/p/erbauer-hex-shank-diamond-tile-drill-bit-6mm-x-67mm/51908

These skate about and take the whole section of tile out, with the kits you have hollow drills which remove next to nothing and leave the ‘core’ to be removed. 

[dpmiller]

what's wrong wth a normal spear bit for this?

[ProDave]

3 minutes ago, dpmiller said:

what's wrong wth a normal spear bit for this?

I was about to say that.  Cheap, they seem to work, and the pointed arrow head bit does not skate around.  Usually sold as a set of 3, 4mm, 6mm and 8mm

 

No coolant needed.

[Nickfromwales]

17 minutes ago, dpmiller said:

what's wrong wth a normal spear bit for this?

Pretty hopeless in porcelain imo. They get red hot and have cracked tiles previously when drilling near the edge. 
 

I use them for ceramics, but only ever use diamond for porcelain. 

[markharro]

and for marble terrazzo which is what we have?

[Onoff]

Use a guide. Lidl sometimes stock a set of drills including a vacuum type guide like the one below that you stick to the tiles.

 

Did all my bathroom with a set of drills like this and just drilled bits of timber to make a guide 

 

 

 

[Alan Ambrose]

I’ve found those suction guides are fairly hopeless as they’re too pliable - or maybe I’m too stupid.  I use a few layers of duck tape to give a tiny amount of support and hold the bit at an angle and run it slowly to create a little lip in the tile. As soon as you have a little arc in the right place you can gently straighten the bit out. Once there’s a little circle there it isn’t going anywhere.