Some of you may remember the blurry pic I posted of a drill that reversed for about 30mm of its length then went normal, with musings of how it happened since I only noticed it sharpening.
Well, I can categorically say after lots of experimentation, its due to the bit snagging in the mill during deep drilling, because I accidentally managed to make another even bendier one
Drilling speed was about 400rpm, into 7074 alloy plate 40mm thick and being fed by hand crank so some degree of sensitivity (I hope).
Im guessing that they are just made of the wrong grade of steel. Its just one picked out a loose lin bin of assorted drills of unknown origins.
Made me grin anyway, once I'd found another and finished the job properly that is.
Well, I can categorically say after lots of experimentation, its due to the bit snagging in the mill during deep drilling, because I accidentally managed to make another even bendier one
Drilling speed was about 400rpm, into 7074 alloy plate 40mm thick and being fed by hand crank so some degree of sensitivity (I hope).
Im guessing that they are just made of the wrong grade of steel. Its just one picked out a loose lin bin of assorted drills of unknown origins.
Made me grin anyway, once I'd found another and finished the job properly that is.
.......snapped a few,never had a drill do that 
