Quote Originally Posted by irving2008 View Post
If I had one :)

Well put a 1.5thou (.02mm) feeler gauge under it and I can push it through in places, so I suppose the answer is 'not very flat'

I have 2 pieces roughly the same size. I was wondering about lapping them together to get it flatter. Thoughts anyone?

A 12" sq 3" thick granite surface plate is about £35-£40 new. So it might be worth the effort.
You certainly shouldn't be able to put a .02 feeler under it even at 30mm means you got Chinese or indian granite.
as for granite a 30mm sheet 3 metres long will bend 30mm or more.
lapping will bring a higher polish but will wear the softer parts of the granite.


If you are near Marlborough Wiltshire Give me a call I,ll give you a couple of pieces for free at 30mm or 40mm.
Google: ramsbury stone for contact details