Taper is too deep to fit my ER11 collets, the cap doesn't press down on them at all so they just free spin within the assembly. I ended up cutting the end off of my print so that the collet stuck out far enough to be pressed on by the cap. worked well enough for my purposes but the bit did spin in the collet when the force to keep drilling my plastic part was too great. using larger threads may make the cap tougher so we could crank down on it more getting a tighter grip. I used silk pla plus because it was what I had on hand. I'd recommend something stiffer like ABS.
