As Bernard said, it is most likely to be a left hand thread on that screw, I came across the same thing some time ago on a grass strimmer. My nabour tried to remove a screw holding on the head, thinking it was rt handed, and sheared it off. Lucky enough I was able to drill out the stub [not easy ] and he was able to get a new screw.

I have removed chucks, after removing the locking screw, by tightening an allen key in the chuck on the short end and taping the long arm with a mallet in the anticlockwise direction.

David

On 29 July 2024 at 17:26 Andrew Tinsley Said:

I have an Hitachi Lithium ion battery drill…

 

I would like to replace the chuck with a good quality unit

What is the model number? Check on somewhere like https://www.sparepartsworld.co.uk/ for the cost of an OEM replacement.

I removed one today and it is Yukiwa Seiko, made in Japan, metal-bodied.

It will most likely be 1/2 UNF thread, which is common to 90% of these. Hence, you could check Makita, DeWalt etc. OEM prices to see how they compare.

As above, the screw is LH thread, the chuck is RH thread. Allen key gripped in the jaws to remove. If you are really unlucky, it will be loctited. In which case, it is better to destroy the chuck to remove it than destroying the gearbox through hitting it too violently.

Look on YouTube for Dean Doherty. He does a lot of these and in particular shows how to destructively remove a chuck without harming the spindle threads.

When I replaced the chuck on my “free”* DeWalt cordless I used a Rohm and have been very pleased with it.

Robert.

* It fell of the back of a lorry, well the rear step of a transit van to be precise. IT was in the case with impact driver charger, batteries ad charger. It hit my car and caused some damage. The van did not stop. fortumantly I was driving a old run-around car so wan’t too bothered. would have. Police said if the van owners reported the drill missing I’d have to give it back but they would issue a fixed penalty for an insecure load :0 There was no name or business card in the case. The chuck had one jaw chipped. There was a couple of SDS drillls in the case which might explain that. With a new chuck it’s been a great drill.

Robert

Do you recall which Rohm model you used ?

The chuck on my otherwise-lovely Bosch GDR 10,8 has always had too much run-out.

MichaelG.

Thanks for that, Bill

MichaelG.

.

Edit: __ two things from the link:

For extreme use on hand-operated percussion drills and drills up to 1300 watt with mounting thread or conical mount.
Benefits
Concentricity of up to 0.25 mm

1. it is probably heftier than I need

2. that claimed concentricity looks disappointing

MichaelG.