Gordon Shumway wrote:
On Fri, 19 Jul 2013 19:34:13 -0700 (PDT), leza wang
wrote:

Hi all
In this video minute (0:40) the person is using machine to screw.
What this machine is? a drill with special head or what? I have a
drill but not cordless and i am thinking to use it as a screw driver
to screw a big board for my front house, or do I need special
device? Thanks

https://www.youtube.com/watch?v=fkOVc9FtozA

The tool you are referring to is a battery powered drill/driver. It
can be used to drill holes or drive screws when the proper bit is
inserted in the chuck. The tool being used in the video is a Dewalt
drill/driver similar to this one:

http://www.dewalt.com/tools/cordless...s-dc759ka.aspx

DO NOT use a corded drill to try to drive screws! If you are not
familiar with this operation you can easily hurt yourself.

Corded drills don't have clutches to adjust the torque for that
application. Even if it is variable speed drill it is very difficult
to control the speed for driving screws. They are not intended for
that job.

That seems to be overly dramatic to me. If the OP has a variable speed
corded drill, and mostly just wants to use it for this one job, I don't
think it would be any big deal to do so.

I have used a variable speed corded drill to drive screws when I happen to
not have my battery powered drill/driver with me. Yes, one needs to be
careful and try to keep the drill speed low, but it's no big deal.

And, I don't see where the "danger" part would come in. It's not a power
saw or angle grinder where one could lose fingers etc; it's a drill.