There is an article (I believe it comes with your threader) Step-By-Step Threading An Acorn. On page 4 is a chart of depth of cuts for the different heads. While Victor (who is a Master Machinest) does not find these figures exact I have found them more than accurate enough to give me great threads with the different heads I have. I have a machining backround having worked at GE running various lathe and mill type machines for over 30 years. I myself have no problem using dial calipers as I'm making threads in wood (yes wood moves). I position the jig by making sure I put pressure on the jig to sit against the ways of the lathe closest to me. With the 16 pitch that I use the most I touch the wood then back off and move in .018 and take my first cut. After backing out of the cut I then move it in another .017 (that is the .035 total on a side from that chart for the 16 pitch) and take my second cut. Now if you have made the size of the second piece correctly and do the same procedure you will have a pair of threads that work today, tomorrow and hopefully forever. I have not had a problem with the pieces going out of round or being bothered by a little wood movement. I use dry wood. I think you will find that anyone that owns the Baxter Threader will tell you it is a fine piece of machinery that has no match (again you get what you pay for).