On 26/09/2019 14:59, GB wrote:
On 26/09/2019 14:45, The Natural Philosopher wrote:
On 26/09/2019 14:22, GB wrote:
I have a concealed cistern behind MDF, which has been tiled.

I am fitting a new flush valve in place of the old syphon. It's
mostly done, but I need to recess the button. That needs a 40mm hole
through the tiles and MDF, in place of the existing rather ragged
30-35mm hole.

What's the best way of doing that? 40mm drill will tend to wander. I
have a 1/2" belt sander, but that'll take ages. Any suggestions please?

https://www.permagrit.com/small-rotary-tools/

These willl take down tiles as well as MDF
(wear a mask)

Or

https://www.permagrit.com/radius-ext...e-file-coarse/

Permagrit tools are ruddy brilliant actually




I've ordered one of these:
https://www.amazon.co.uk/dp/B00VSZ1F...740111_TE_item

For under £2 it's worth a go. As long as it does this one hole, that's
good enough.

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.

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.