I need some LARGE wood dowel screws - the double ended wood
screws the small variety of which are often used to fix wooden knobs
to doors.

I'm joining 5"x5" timber baulks upright onto 10"x5" oak railway
sleepers, so need perhaps 10mm or 12mm diameter and maybe 100 mm long.

Google finds lots of tiny ones but no big 'uns.(well not quite true -
I found a supplier who offers 1" x 8" screw dowels. I rang them to
check that that was 1" diameter by 8" long which they confirmed, but
when they arrived they were 1" long by No 8 !!!!!!!!! )

Anyone know of a supplier?

AWEM