On 06/08/2018 15:57, Bert Coules wrote:
Something has gone amiss with the chuck on my ageing budget SDS drill
(Ferm FBH620 from Screwfix many moons ago): tools no longer twist-and-lock.

I've seen fixes online but the prospect of dismantling the chuck doesn't
really appeal.Â* A quick test has revealed that the tool still works
perfectly well as a chisel (which has always been my main need) except
for the inconvenient fact that the bit keeps falling out.

Is there any reason why I shouldn't take my most-often-used chisel bit
and simply stick it in the chuck?Â* A spot of Araldite or even superglue
on the very end ought to hold it, oughtn't it?

The thing about a SDS chuck is that it does *not* have a rigid grip on
the bit. It retains it, and stops it rotating relative the the chuck,
but it must allow it to slide in and out a bit for the hammer action to
actually work.

The sliding hammer inside the drill smacks the back of the bit - which
accelerates it forward, and the chuck lets it slide - but catches it
before it is actually ejected from the machine. If you fix the bit to
the chuck it won't work, and you can't fix it to the hammer either (it
only needs to contact the bit on the forward stroke).

So in short, you need to fix or replace the chuck, or treat yourself to
a new drill... (and a 2kg class Makita or similar will be a complete
revelation after the Ferm!)



--
Cheers,

John.

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