Making a Custom Pen Tip Register for a Roller Ball or Cross Style Kitless Pen

[Angusga]

I'm wanting to make some custom hardware for ball point pens out of various metal that I can apply custom finishes to. The internal cutting for a press fit tip seams especially confounding. A small ball mill to finish the bottom of the cone seems doable but I'm not sure that even a tiny boring bar will fit far enough. I'm thinking tapered reemer. I can probably find one from Harvey Tools that I can match the exterior cone to. Has anyone here attempted this? The tips could be threaded to go into a press fit nut. The end caps and center bands are not a problem. Clips present their own issues and any ideas for them are more than welcome too. Thanks.
Gordon

 

[Curly]

I just took a look at a few store bought pens and a Sirocco and all the tips are step drilled or formed like they were. Tip hole for the tip of the refill, then the next size up for the spring and if needed the next size up would be for the body of the refill if a Parker type. You can do it one drill at a time until you know the diameters and lengths needed, then you could get step drills ground so you can do it in one operation. Rick Herrell in the market side of the forum grinds step drills to order. Playing with tiny tapered reamers would entail more work than needed and you'll still need to step drill some of it since reamers don't like to remove lots of material.