Cutting a composite worktop?

[Mark300zx]

Bought a worktop for a basin in the bathroom and took the basin to the shop for them to use as a template, plumber says the hole for the waste isn't big enough as it hasn't accounted for the nut to go around the thread.

Worktop company are being awkward, the hole should be 80mm but is 36mm, how difficult is this to cut, it doesn't have to be pretty as the sink is 420 in diameter?

[Mark300zx]

iirc it is 30mm, and yes the basin sits on top, I have just been looking at longer wastes which the plumber said he couldn't get, may be an easier solution!

[Mark300zx]

Thanks but what bit shall I use as this is quartz composite?

[Mark300zx]

Even took the sink to the workshop for them to cut the hole!!!!

Unfortunately it's all tiled in now

[Mark300zx]

Thanks how would that work, the gap between the sink and the worktop would have to be sealed to avoid any overflow water leaking???