nog wrote:

Soorry to sound higgor'nt but what's SDS?

A google of this group will get you loads of discussions on the topic.

In summary, it is a highly effective hammer drill system that often uses
a pneumatic compressor to deliver the hammer action. The drills all have
a standard sized shank that is splined, these lock into a matching
chuck. The hammer action hits the end of the bit itself rather than the
chuck.

The result is a hammer action that delivers many hundreds of times the
energy per blow. Hence you can drill straight through hard masonry like
it is hardly even there, in circumstances when an ordinary hammer drill
would make a lot of noise while making an every wider and not deeper hole.

The better models also have a rotation stop mode where they can be used
as a lightweight breaker with a chisel bit. Ideal for chasing walls etc.

See here for selection of decent examples of the species:

http://www.lawson-his.co.uk/scripts/...hisel%20Drills


--
Cheers,

John.

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