Cordless impact drivers look a lot like
driver-drills with 1/4-inch hex collets
instead of three-jaw chucks, but
appearance is where the similarity ends.
These tools provide as much power as
you'll ever need from a cordless tool —
more than twice as much as a comparably
sized driver-drill.
Unlike the continuous torque of a
regular driver-drill, the output of a
cordless impact driver is mechanically
converted into an intermittent rotational
force (see Figure 1). As a result,
there is no noticeable torque reaction
at the tool or at the workpiece and,
even with all the extra power being
delivered, there is little or no damage
to the screw heads.
With the slightest forward pressure
and an easy grip on