
1/4-20nc worked as expected. They were cheap, so I treated them carefully. Lots of drilling oil. I was able to easily cut sixteen holes with 1/4-20nc and it is in good enough condition to use again. However, I tried #10-24nc and it broke like a dry branch the first time I used it and got stuck in one piece. I haven't tried the others but I suspect they will be the same as #10. I can try a two step process of cutting through the material but not letting the overhang penetrate the part. Then I will try to flip the strands manually afterwards.