07-30-2012, 01:40 PM
I always believed the reason for 29° was so that the trailing edge of the 60° threading tool would be 1° shy of parallel with the compound. That way all the cutting will be done with the leading edge of the cutting tool.
Busy Bee 12-36 lathe, Busy Bee Mill drill, Busy Bee 4x6 bandsaw, Homemade 9x17 bandsaw, Ad infinitum.