Drill hole in tiled MDF

Do you mean you are trying to enlarge the ragged hole, or are you starting again with a new tile.

Or

I've ordered one of these:

Apparently, the technique to use is either to make a 40mm hole in some timber to use as a guide, or to start the drill at an angle, to make a groove to hold it in place.

WOW!

I was looking for that...yes that is way better.

Agree with both techniques .

Do you have any of the original tiles left? Brian

Probably. Hopefully, I won't need to search. :)

Fix a bit of wood across the existing hole so you have a centre. Just glue it to the back of the MDF with No More Nails etc.

Mark the centre and drill your new hole with a diamond core drill.

Just watch that the mdf doesn't burn as it will get hot tying to drill it with that.

A rotary tool and a drum sander might be better after you reach the mdf.

Useful link, not come across permagrit. I was going to say that for enlarging a ragged hole I'd probably use an abrasive tool in a Dremel or similar, noting that the cheap ones that typically come with them are often single use.

That seems too good to be true to me. I've tried a few cheap diamond tools (e.g. Dremel sized cutting disks) and usually been disappointed.

Make a nice wooden trim etc to cover the hole edges?

it might have a single piece of microscopic diamond grit on it. If you're lucky it hasn't fallen off already. Use the TCT version, diamond is pointless at best.

NT

Decent diamond-coated tools are not cheap, and work well provided you don't push them too much and get them too hot. TCT is ok for most things, but will be at its limit with vitrified porcelain tiles (I don't think that the OP has stated what the tile material is).

I have had great sucess with cheap diamind coated tools. They work excelllently for half a dozen holes, then the diamond wears off and thats it.

But that is all you normally need.

TCT is cheaper, just as effective unless you're drilling something of very exceptional hardness, and lasts

NT