Trying to put a new chuck on a Makita 8391D 18 V combi drill and cannot get the locking screw in the middle undone. Supposed to be a left hand thread. I've tried normal screwdriver, T-handle driver, hex bit in a small ratchet wrench and the 18 V Makita impact driver that came with the drill. Contemplating cutting the chuck apart for better access and, if necessary drilling the screw head off. Making a replacement screw won't be hard.

Before I get destructively drastic has anyone any suggestions. Be unsurprised to discover I've missed something blindingly obvious.

Power Tool Centre ltd of Liverpool **LINK** did me an excellent deal. Change from £90 for two 18V batteries and a chuck including delivery, all genuine Makita factory parts.

Thanks.

Clive

Thanks for all the assistance gentlemen with a special mention for herbert for a very useful link now downloaded and copied into my manuals folder.

In the end nothing worked so I cut the offending beast off! Having done the deed and figured out the quickest approach I figure the brutalistic approach can be done in 1/2 an hour or less so it will now my preferred method if the chuck doesn't succumb immediately to the book method. I went all round Robin Hoods barn and took around 2 hours due to being not sure where to cut but if anyone else wishes to try here's how. The body is quite soft so an ordinary hacksaw and file will do fine.

1) Dig out the little spring ring on the end, slide off chrome cone, plastic sleeve and ball bearing thrust ring.

2) Ferret out the jaws and knock the thin toothed ring off, it only pressed on and gets in the way of holding when cutting.

3) Hold the chuck body in a vice and carefully cut round at the base of the jaw slots. Have to go round rather than straight across as the cut will be pretty much level with the bottom of the screw head. My screw spun straight out with the impact driver.  Only Lawyer Murphy and the Gremlin Squad know why it wouldn't shift with the chuck in one piece.  If yours still won't move consider a bit of heat or my favourite of welding a nut on so you can really lean on it. Power Tool Centre linked to in my first post sell the screws at £3.45 so its not the end of the world if you have to destroy it.

4) With the screw out of the way cut straight across at the base of the front flange. This cut was about a mm clear of the threaded spindle end on mine. Probably wise to check it will be clear on yours and adjust cut position if need be.

5) File the remaining cylindrical part of the body down flat until you just reach the thread. With care you will be able to see that you have reached the thread before actually breaking through onto the spindle. Filing into the flange next to the drill doesn't matter but if you go right through it would be easy to damage the drill body. Flip 180° and do the same.

6) Carefully saw through the remaining flange and plastic ring in line with the two flats. The hoop strength is now destroyed and things will unscrew quite easily. I lightly gripped it by the flats in a self grip "Mole" style wrench and ran the drill in reverse to spin it off. Bit of a jolt to start so hold tight.

I imagine that all the cordless drill keyless chucks are pretty similar in design to the 13 mm Rhom brand one on my Makita so a similar approach should be possible for other breeds and sizes but it would be wise to check that the cut positions are safe and make adjustments to prevent damaging the drill shaft if need be.

Clive

Edited By Clive Foster on 02/12/2014 16:03:33

Maybe not so brutal in practice.

On reflection I suspect that I, and many others no doubt, are illogically reluctant to use surgical methods of removal on stubborn components which will be scrapped anyway. After all the bin doesn't care if it comes off in one or ten pieces. Realistically you are much more likely to cause collateral damage by getting aggressive in attempting to make the book method work on something which is clearly much to tight to remove in the approved manner than you are by careful and thoughtful dismemberment. In this case its mostly the gearbox that holds things steady against unscrewing forces. A potentially expensive component to damage.

My main worry when resorting to surgery was that the chuck components would be either hardened or a semi tool steel requiring angle grinder or diamond files to dismember. An angle grinder in particular being much harder to control closely than a files and hacksaw.

Clive