All true. Just bear in mind that none of the figures I used were based on anything I have actually measured. In reality most lathes probably have far more error at the tool post than what I stated. My figures we're hypothetical, and my intention was to show that in theroy (a perfect word) the use of a 100/127 transposing gear would produce a thread with 0% error. In reality we all know that a perfect world does not exist. The original question was more about the amount of error of a 100/127 transposing gear, not the end result at the work piece.