Andy Dingley wrote:
On 5 Feb, 22:09, Housemartin wrote:
I have to join some extra wide work top at approx 90 deg.

What do you mean by "oak"? If it's real timber, then remember to
allow for expansion & contraction with moisture, which can be sizable
across the grain. It sounds like you're building a cross-grain joint
here, so that's potentially 1/2", maybe even 1" you're looking at.
Tosh.

At most .05% on well seasoned wood. To get 1/2" would require over 8 ft
of top and total soaking.

Ive done it here simply by running a router into one top to make it
perfectly square and slightly inset. Same on end of other piece and and
hand rounding thee other pice to match.

I clamped it underneath with battens and used PU glue on the joints. Its
been fine for 8 years.