Here is a video of the action on trapezoïdal threading, bad image quality, but I don't know if i can put a HD video for all people, it needs high velocity connection
filetage mode automatique trapézoïdal | lecollectionneur.ch | Pierre_G.
This is a 9mm.X2mm. at 30°(european normalisation) with ETG85 steel, it don't need the use of the opposite tool(I don't know the word for "lunette à suivre") with HSS tool made on the sharpening tool and optical contro gauge for the right angle.