Lack of rigidity in the feed of the drill can also cause it to run away and get worse. Sometime reducing the cutting angle of the drill by applying a grinding wheel to the inner edge of the flute will reduce the grabbing action of the drill.
Doesn't answer the question but this is interesting :
The problem I've had with those is that they don't last all that long.
Bill
I?m still on my first one, so I can?t say how long they last, but I?ve had it three years so far.
I inherited mine from my father, and he died in 1994.
*HOWEVER* I have only ever used it on wood; it never occurred to me it might cope with metal too. (Maybe the answer is "it doesn't".)
"Recommended for use on alloyed and non-alloyed steel, high quality steel plate and soft and hard woods ..."
They can be resharpened more easily than twist bits.
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