On Sharpening Twist Drills

There is this thread http://ift.tt/1jvLIBK on the English 'Model Engineer' website that makes for interesting reading on drill sharpening. There are quite a few pages and I have not read them all, but on the first page, the moderator recounts his earlier career working for a company making piano movements. They drilled thousands of holes a day into wood, and the positioning was often to within a half thou, and hole sizes would be to within tenths of thous. No commercial drills would drill to size from the packet, so they would be graded, and remachined and resharpened to size. When they were installed, test pieces would be done and it might still take some hours of tuning before the machine was passed by the inspector for work. Some of these drills would then go on to drill over 30,000 holes before they were changed out. Well worth the read if the weather is as drizzly as it is here:rolleyes:

Rob.