I sharpened an engraving cutter to a finer point, approximately 55 degrees included angle, instead of 90 degrees, with a clearance of 1/4 of a thousandth of an inch per 20 degrees rotation of the tool, with an initial clearance angle of about 13 degrees ( I hope I remember what I mean by all these numbers, so I can do it again ). The flat of the cutter was no more than 0.1mm diameter, which is dangerously fine. The material was aluminium alloy. Cutting time about 10 hours. 50mm/minute horizontal feedrate. 20mm/min vertical feedrate. The result was beautiful. I can't wait to see the impression it makes. I hope it doesn't get damaged in use too quickly, as it's not as hard as steel. Interesting marks on the surface must be because of a lack of coolant; I couldn't stand there for 10 hours, so I just put some oily paraffin on the surface, but I guess it got used up or dried out while I was out at work.