On Sun, 14 Jul 2013 11:11:46 -0500, "Terry Coombs"
wrote:
As I said , this tap cuts an oversize thread , it
measures 10.11 MM . Allowing for truncated thread profiles , the tap should
measure just UNDER 10MM , not over .

The OD of normal taps is always larger than the nominal thread size.
Look at the thread tables in Machinery's Handbook and you'll see that
the major diameter of internal threads is the nominal diameter with a
plus tolerance.

10.11 mm OD for an M10x1 tap sounds about right.

--
Ned Simmons