Machinist

[Lawrence London <lfljvenaura@gmail.com>]

comment on using keyed drill chuck for tapping
http://www.practicalmachinist.com/vb/general/milling-lathe-again-pics-202899/

For the uninitiated, you should absolutely hold a tap in a drill chuck unless you want to spend lots of time cranking on a tap handle. It's called power tapping and like Ray has shown in his photo, use a key chuck and tighten it just enough to drive the tap. If it meets too much resistance, it just spins in the chuck. Don't use a keyless chuck for tapping however unless you're sure it won't bind. Keyless chucks are self tightening and will snap the tap off in your part if it meets any more resistance than it should.