Drill chuck removal

[xerxes]

I've just acquired a secondhand Elu mains drill (EMD403); I'd like to change the chuck for a better one if possible.

Looking inside the chuck where I'd expect to find a retaining screw (the drill has reverse), I can see what looks like a screw. It has a very shallow slot, with a dimple in the centre. It seems to turn freely in either direction, without undoing or tightening. The slot is so shallow that it's hard to get a screwdriver to engage in it.

(The exploded diagram I've found for the drill does show a screw, but the definition is too poor to give any details.)

On the shaft behind the chuck there are no flats where I'd expect to find them, to hold the shaft while the chuck is unscrewed.

Does anyone have any ideas on the way to remove this chuck? It's marked 1/2 - 20, so I know it's a screw mount.

[ColJack]

screw is probably a security screw.. the dimple in the middle prevents the use of a regular flat screwdriver.

to remove the chuck, screw it clockwise, they have a reverse thread..

the "shock" method is the way to remove the chuck.. put an allen key into the chuck and grip the drill securely ( a vice works well ).
strike the allen key in the right direction.. it WILL spin, so watch your knuckles..
it should shock the chuck loose..
if not try it again until it does..

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[xerxes]

Thank you. The centre of the screw has a dimple (a depression, concave); it doesn't prevent a normal flat blade seating in the slot. The problem is that the screw doesn't seem to be threaded, either left or right hand: turning it doesn't do anything.

And yes, I've already tried the usual method of fitting a large hex key in the chuck and smacking it with a hammer. It doesn't have any effect.

[gregers]

you might also find that it just unscrews,iirc anti clockwise.

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