I have been doing lots of threading lately via the LS threadmills and the best guide ive found has been the NYCCNC spreadsheet.
However, its still trial and error if you dont know the crest dimensions. Does anyone know what they are? Ive tried estmating at 1% of flute diameter but its not close enough. Ive got lots of materials and other variables, but knowing the crest dimensions will make my starting points for PDO closer to the proper result.