Replies

1. 
   JohnWW | Feb 10, 2009 01:49am | #1

   Although rare, there are drill bits of all types that are designed to cut when turning in the reversed or left handed direction. Some are made for automatic drilling machines where the gear train driving the multiple bits will have every other bit turning in the reversed direction.

   The other most common use is for bits intended for drilling out broken screws and bolts. These bits are made that way so that if they grab the broken off hardware while it is being drilled out the bolt or screw will be backed out of the hole rather than being driven further in.

   John White

1. 
   LarryMartin | Feb 10, 2009 03:01am | #2

   Thank you, John.