ever hear of threadwell taps?
I found a set of number taps
fine and course thread of  # 4 --# 6  #8  # 10 # 12   and 5/16 the course thread of no, 12 is missing the vise is unmarked  information is scarce  bob w.

Threadwell Tap & Die Co, Greenfield,MA (50's-60's) I think they were Threadwell Tool co in the 30's, but I'm not sure about that.

Here's the set: http://books.google.com/books?id=0N4DAAAAMBAJ&pg=PA280&dq=Threadwell+Tap+%26+Die+Co&hl=en&ei=RtbSTrCMLoargweczIGyDQ&sa=X&oi=book_result&ct=result&resnum=4&ved=0CFcQ6AEwAw#v=onepage&q=Threadwell%20Tap%20%26%20Die%20Co&f=false