On 11 Apr 2008 13:19:18 GMT, (Andrew
Gabriel) wrote:

In article ,
(Graz) writes:
On Fri, 11 Apr 2008 13:32:42 +0100, "Roger Mills"
wrote:

Insert the key so that it is in a horizontal plane on the RHS when looking
from behind the drill (as per the illustration at
http://www.mtmc.co.uk/product.asp?co...yes&P_ID=19641) and give the
end of the key a sharp downward tap with the hammer. It should then unscrew
easily by hand.

I found that after about 10 years of doing this to change
attachments, eventually the gearbox breaks (a splined shaft
stripped). Changing attachments on drills is rather a thing
of the past now though.

Presumably with the chuck open as far as it will open?

Doesn't make any difference -- you aren't putting any force
across the chuck openening/closing mechanism, i.e. you aren't
aiming to twist the chuck key, but rather to twist the chuck.

I thought the idea was to have the chuck as far open as it would go
and then apply impact force to the chuck key in the direction of
opening the chuck, if you see what I mean. That's what worked for
me, anyway.

In any event, I was under the misguided impression that all Jacobs
chucks were alike. The one that came off the drill had a half-inch
threaded stub attached, the one I was hoping to replace it with
didn't.