01-20-2009, 09:50 AM
A punch might work, although they often create a burr around the opening and can distort an even wider area around the resulting hole. Why such a large hole? A smaller screw, such as 00-90, 1-72, or even a 2-56 will have a head sufficiently large enough to hold pick-up wipers in place. The smaller drill bit, with cutting edges much closer together, will have less tendency to "grab" as it breaks through the thin sheet, too. Use a drawing compass point to punch a centering mark - perform this operation on a hard surface, such as a surface plate or even a sheet of glass - this will keep the bit from wandering. It doesn't need to go right through - just a "dimple". If you absolutely need the larger hole, drill it in stages, starting with a smaller bit, and working up to the size you need.
Wayne
Wayne