Hi. Just a small piece of info to impart to the more novice pen turners. I have made a fair amount of classic fountain pens and roller balls. I am talking about the ones with center bands in the middle. I found that when you come to turn a 5mm tenon down to the brass tube for the centre band to fit on, its fine to just use a small parting tool to cut it back. I am talking of wood here. If you do the same with acrylic, or a plastic based product, I found as soon as I got down to the brass tube, in acrylic it spoilt the cap by chipping it. I got over it by measuring the distance that I needed to take the acrylic of, and with my skew turned perpendicular, cut a line down to the brass tube. The once you have cut the line, when you take the rest of the small band size piece of acrylic,, it will not chip, therefore not spoiling and expensive acrylic blank. Hope this helps.