what the difference between an impact driver and a hammer drill?

I've a feeling this is a groan type question but anyway. what *is* the difference between an impact driver and a hammer drill?
I have a (cheap) hammer drill that's fine for driving wordscrews of various flavours and drilling holes (ie can use screwdriver bits and twist drills). It has a setting for "hammer" that I *guess* may be for use with the old-fashions Masonmaster bits for drilling concrete/brick etc. I never use that now as I have an SDS frill which does that. That's a kind if "impact" setting isn't it?
So, does an impact driver also drill holes :-) Seriously though folks what is it used for (as they seem quite expensive). What can I do with an impact that the hammer drill does not do. v.m. thx.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
dave wrote:

With a hammer or percussion drill the impacts are along the axis of the bit (i.e. in and out). With an impact driver the impacts are angular around the rotation axis of the bit.
Ordinary hammer drills:
http://www.diyfaq.org.uk/powertools/drill.htm
SDS version:
http://www.diyfaq.org.uk/powertools/sds.htm
Impact driver:
http://wiki.diyfaq.org.uk/index.php?title=Impact_driver

Yup, ordinary hammer drills need masonry bits (or multi-material ones) when in hammer mode.
SDS require special SDS masonry bits.
Details of the various types here:
http://www.diyfaq.org.uk/powertools/drillfaq.htm

It can, but is not ideal in most cases. You need either an adaptor chuck for it, or hex shanked bits.

See the faq above. However in summary - if you put in lots of screws, you will find an impact driver a very fast and easy way to do it.
--
Cheers,

John.

/=================================================================\
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

For big screws cordless impact drivers are the big thing now in the US for carpenters. A hammer drill hammers, impact drives screws by turning. Hammer drills are for concrete.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
In article

The makers have a great deal to answer for - Bosch call some of their hammer drills impact ones. And an impact driver was a special type of screwdriver you hit with a hammer to turn kinetic energy into rotary motion long before these cordless impact driver arrived - I have one which is 40 years old.
FWIW, impact is good for smaller screws too - less effort to stop the drill turning. So less tiring if used a lot.
--
*Pentium wise, pen and paper foolish *

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
dave wrote:

It is for drilling masonry. The drill is hammered in and out, like the SDS but on a much smaller scale. Better than just rotary drilling, but nothing like as good as an SDS.

SDS Frill :-)

They don't really do holes. The bit is hammered round and round, not in & out. Will put in a 4" coach screw, no pilot hole, in around 4 secs. Worth the money if putting in lots of big screws.
So, an SDS is a big improvement over a hammer drill when drilling & an impact driver is a big improvement over a drill driver when screw driving - especially with big screws.
--
Dave - The Medway Handyman
www.medwayhandyman.co.uk
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.