tips needed for square hole near edge

[mfu]

Hello everyone,
our bathroom reno is nearing the end, & our contractor is having a hard time with a 12''x24 porcelain tile that needs to be square-holed about 1.5'' to edge.

He already has 3 or 4 shattered tile & our 5% overhead is quickly fading.
He's using an angle grinder w/diamond blade that seems to cut pretty well.

On his last attempt last evening, he pre-drilled holes in the corners to alleviate stressing the edge of the tile, but shattered yet another tile anyway as soon as he was cutting along narrow edge.

He's setup outside, slightly below freezing point in our neck of the wood, with the finished side on top, over a scrap tile.

Can you guys throw me any ideas so he doesn't spend the better part of this coming monday breaking tiles one after the other?

[dbol]

you might want to try gluing the piece in place letting it dry then cutting it. Angle grinders have there place but they aren't great for nice clean cuts. Hard porc. is known for breaking.
Also you can place the tile onto a bag of sand or thinset and cut. You want to reduce the vibration as much as possible.

[mfu]

Hi
I am afraid glueing in place then cutting is not a viable option as shower hardware is already in place & removing it would set us back too much.
Indeed the grinder doesn't do the cleanest cut, but since it'll be covered with shower knobs finishing plate...
Seems like a good idea to try to reduce vibration on the piece being worked on.

Any other tips & ideas?
For instance, instead of angle grinder, would you guys try other tools, like wet saw with the tile hand held, or scoring tile then trying to punch cutout?

Thanks in advance!

[Raymondo]

You could try epoxying on a piece of Kerdi to the back of the tile, then doing the cut. Or, if you have a place nearby that has a waterjet, they could do the cut no problem.

[tileguynky]

Taking time with a wet saw would be a good way to make the cut.

How is the tile supported?
Is the piece vibrating while cutting?
Is the angle grinder bouncing/vibrating while cutting?
Is the tile getting hot while cutting?

Any of these or all of these could be contributing to the tile breaking.

[mfu]

Tile guy:
The tile to be cut is layed flat on a scrap tile
It does not seem to vibrate, nor does the grinder
While we sprayed the drill bit, we're not spraying the blade that show no sign of overheating.

Raymondo:
Waterjet ??? I am totally unfamiliar with this concept; am I to understand one could cut a hard porcelain tile using only high pressured water. Sounds too good to be true

[jnaak]

waterjets can cut through several inches of material...steel, tile, whatever. i believe there is an abrasive material mixed in the water. not too good to be true. i use a diamond hole saw for such applications. it was a little pricey, but worth it.

[Houston Remodeler]

Its the vibrations that shatters the tiles along with any thermal expansion of the blade while cutting. The slower you can get that diamond blade to spin the better.

If you have a dewalt type wet saw, use the 'dewalt dip' method and cut from the top down. as suggested.

If you slightly cut the face of the tile, then cut again from the back side you'll fare better

[eurob]

What is the size of the hole ?

[mfu]

It is quite similar to the posted pîcs above
Our holes are as follow:
big one about 4x6, small one about 2x2
The small hole doesn't seem too much of a challenge, but the big one follows closely the tile edge & always ends up splitting from one corner or another.

From what I understand, our worker could also go with diamond hole saw; he would need to do 3 round holes; he would probably be able to cut a little farther from the tile edge this way...

I am trying to find a place nearby that do waterjet cutting, without much success so far

[eurob]

Hello John,

You can call here

http://www.mosaiquesurface.com/en/index.php

The coordinates are at the bottom of the page.

I know they do have waterjets , but do not know if they can accomodate you. Normally the holes shouldn't be a problem to do with the right tools.

[mfu]

Thanks a bunch for the link
At least we now have a last straw if all else fails
Thanks everyone for your input

[Tilepro04]

Ive had this come up a few times. First time i used the mesh tape and covered the entire back with the tape then epoxied the entire back, it worked. Second time that didn't even work. The trick is to drill a hole on every corner. This will transfer the crack from hole to hole if it decides to crack. Thanks to my glass installer for giving me the idea. worked like a charm. Took me 13 tiles before I called him

[tileguynky]

While the blade might not be showing any signs of overheating, it is getting hot. Like Paul said the thermal expansion (even slight) and a little bit of vibration (blade out of round as example) are the main cause of the tile cracking during the cutting process. Have you tried to put a damp sponge on the side of the blade while cutting?

Water, and slow going are going to be your friends while trying to make this cut. Do you have a scrap piece of concrete board or plywood to cut on. Those work better than a piece of tile, in my experience. Also, make sure the support piece is at least the same size or a little larger than the tile being cut.