On 6/20/2014 8:30 PM, nestork wrote:

You can't use an ordinary masonary bit in a rotary hammer. Well, you
can, but the chuck you put the masonary bit in will be shaken apart.
Those Jacobs chucks are press fit together, and normally that's enough
to keep them in one piece for decades. But, if you mount it in a rotary
hammer, you'll shake it apart.

CY: Masonary bits are designed for hammer drills, eh? Why would a hammer
drill fall apart cause you're using the bit designed?


Years ago I bought a Hilti TE-10 rotary hammer. It had both "rotation
only" and rotary hammer modes on it. For use with the Rotation Only
mode, it came with a keyless Jacobs chuck mounted on an SDS shank so
that I could use twist drill bits up to 1/2 inch diameter in it.

CY: Now we see a bit more detail.

However, the owners manual for the tool warned never to use ordinary
masonry bits in this Jacobs chuck for drilling masonry

CY: Ah, so you can't use a detachable Jacobs chuck for masonry.....

because the
pounding action would shake the press fit Jacobs chuck apart, thereby
wrecking a $75 or $80 accessory. The SDS system (patented by Bosch)
allows for the forward and backward movement of the drill bit while it's
turning, and is designed to stand up to that shaking.


CY: Mine was Metabo, and I was very pleased with it.


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Christopher A. Young
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