Looking for a REAL answer...

[RodKirby]

Google doesn't help!

What is the difference between "A Hammer drill" and an "Impact driver"?

I was able to get a very good deal (discount + price matching = A$200 ) on this:

http://www.justtools.com.au/prod3231.htm

Great power for 10.8V - I'm a happy camper.

Anyway, here are my definitions

Hammer drill: Adjustable chuck, hammer or not, (relatively) slow hammer. All size drill bits up to chuck capacity. Adjustable torque.

Impact driver: No chuck, "fast" hammer, for "driving/removing" only.

My point is, they both "hammer"

Please tell me if my definitions are "correct", or a bunch of ...

[Russianwolf]

Going off memory, a hammer drill spins the bit in one direction, while impacting it into the material. As if you were striking the back of the drill with a hammer.

An impact driver provides impacts in the direction of spin. Acting similar to a torque wrench.

[atgcpaul]

A hammer drill oscillates the drill bit up and down as the bit is spinning so it
punches into the material--usually something very hard like concrete.

An impact driver uses a spring loaded hammer that is wrapped around the
driver shaft. When the bit meets resistance as it's driving in a screw, the
spring gets wound up and the hammer is released. The force of the hammer
perpendicular to the drive shaft helps to spin the bit but does not make the
bit move up and down as in a hammer drill. If the bit did move up and down,
then there would be a good chance your bit would loose contact with the
screw head and slip off.


Paul

[leehljp]

Different directions for the application of the force/power:

The purpose/function of impact drivers is torq.

The purpose/function of hammer drills is forward thrust (hammer).

There is not a huge difference in the feel, therefore perception is that they will be the same. However, the result is totally different because of the direction of the "force" applied to each.

That is "my" definition.

[LCHIEN]

I agree with all the guys above.

The Hammer drill impacts along the axis of the drill motion hammering the bit into the material being drilled.

An Impact driver (not really a drill) applies rotational impacts to drive the fastener in or out. One such advantage is that it works against the mass of the drill and the stored energy impactor to provide the impacts and won't twist your arm off while provideing considerably higher torque than possible with a regular drill.

Hammer drills will usually have chucks for drill bits but impact drivers have 1/4" quick change hex holders for various fastener bits. Altho you can get drill bits with quick change hex shanks they're not recommended for this application.

[LinuxRandal]

Then you have an impact hammer (most common pnuematic), which has a socket drive size to hammer away at bolts/nuts, while trying to spin them on or off.

So there are three types of tools.

[LCHIEN]

I thought the pnuematic impact tools were just higher powered versions of the impact driver with standard socket drives (1/4, 3/8 and 1/2" square drive). I.e. they don't hammer in the axis direction, they rotary impact.

[LinuxRandal]

I thought the pnuematic impact tools were just higher powered versions of the impact driver with standard socket drives (1/4, 3/8 and 1/2" square drive). I.e. they don't hammer in the axis direction, they rotary impact.

See if this can explain better then I can. I knew there were adapters to convert an impact wrench (impact hammer), into a hammer drill (couldn't remember the term and found it due to this link:

http://www.right-drill.com/

[RodKirby]

Many thanks, guys!

Your concise explanations sure beat anything I could find using Google