Ok, Tweaks, here you go. This is from a post I just did on the Vectric forum as well:
I use a tap guide (for threading) and quite honestly, the hardened pointed/ground end works great for this as well, as I used that at first with other projects I've done. I wanted to set it up for a diamond tip though, so I designed an adapter to fit inside with a small set screw to hold what are called "phonopoint" diamonds (cheap!), which are really used for dressing precision grinding wheels on a surface grinder (what I do for my "day" job). It works fantastic and they make the guides with such a nice slip fit, and hardened materials, so it's a quality unit. I've done over 130 drag engravings with it and it's still a perfect slip fit.
(I see Enco doesn't allow hotlinking anymore so here are the part numbers:)
website:
http://www.use-enco.comPhono/Single point Diamond: 388-8860
Tapping Guide: 325-5179
Rendering of the diamond point adapter shown below.
Hope that helps-
Dave