>=20 > Too bad we can't ask the ancient egyptians how they did (or other people = all around > the globe a couple of thousand years ago). >=20 > An example (of many) in figure 3 to 7 here: > >=20 > Note the spiral grooves, indicating a feedrate of the drill of about 0.1 = inch per > revolution. >=20 I suspect those were done the same way that medieval castle builders carved= stone - with what effectively amounted to a round chisel that they kept hi= tting with a hammer, rotating it fractionally between each hit, makes a hol= e rather like a modern drill does. Can't find a web example, but have seen = it demonstrated on the telly. Would be a long hard job, but was the way a l= ot of holes were manually drilled for black powder blasting when doing cutt= ings and the like for early railways. --=20 Scanned by iCritical. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .