Wonder if anyone can help I am looking for a router cutter to cut a
rebate of 18mm wide by 18mm deep but cant seem to find when anywhere
most grovers or biscuit cutter bits seems limited to 12.5mm depths max
and while I could go narrower and do multiple passes I cant think of a
way to get the depth.

For information the grove is to be cut in an enclosed cut-out so use of
a normal router with the work piece on edge wont go. Neither will a
spindle moulder with a wobble saw.

Anyone any ideas please?