Triple lead taps and dies form 3 threads at once. Normally used for the cap threads they help shorten the twist motion needed to remove or replace the cap. Your cap may start on any of the three threads and will effect where the patterns of the pen line up when it is fully closed. The picture shows a generalization of one of the threads in green as it spirals down, If this was the m14 x .8 one full turn would move the cap 2.40mm
.8 x3=2.4 pitch
M 10 x .75 x3 Lead set
1 inch die, I recommend the 8.5 x1 for the interior threads for #5 FP and Roller ball refill.
M 12 x .8 x.3
1 inch die.
I recommend .464 for the pen body for cutting the male threads and a 7/16 drill for the female threads in the cap.
Out of Stock I do have a couple bottoming taps left