Long story short -- I tried making a threading jig and it wasn't accurate enough to suit me (excessive runout), and so I bought a Chefwarekits threading jig. I know this is marketed primarily for threading larger wooden objects but I thought that with a small threadmill I could adapt it for pen threading. I measured the runout of the jig (measured along circumference of my ER32 collet holder) at 0.017" which is too much for threading tiny objects like pens. I tried threading a section just to give it a try and the runout caused one side of the section wall to blow out. I have an email in to them to see if they have any suggestions but thought I'd try the experts here to see if anyone has used this jig for pen threading and what you may have had to do to tune it up. Thanks.