Drill Chuck, Dismantle

Hello Peter,
 
First of all; I do not have knowledge of a Chinese copy chuck, but I would like to issue a small warning - Have a good look at it before committing yourself!
 
I have successfully stripped and cleaned both Jacobs & Rohm chucks, but this is where I cought a cold.
 
To strip a Jacobs chuck, first line up the tips of the jaws with the end face of the chuck, then find a piece of tube which fits over the rear of the body and abuts the back of the closing ring, it should be long enough to allow the ring to be to be pushed off the FRONT of the chuck. I used a stack of bearing outer races.
 
With the sleeving of choice in place and a piece of material at the front to protect the face,put the assembly in a vice and press the sleeve off the front of the chuck. Wait for a loud bang as the sleeve is pushed off the split closing nut.

Seperate the nut and remove, but examine the jaws before removal as they are usually marked for position, The teeth end in different places and there are marks in the slots into which each fits.

If this is not so or it all goes wrong, fit the jaws aligned with the end as before and try to fit the nut. If one jaw is sticking out, swap them around until the tips are level and move in and out evenly as you turn the nut with your fingers.

When all is well, use the spacer/s and a piece of material to protect the back and press the sleeve back on. When apart you can see that with the jaws so aligned, the inner ends will clear the sleeve.

Now for the rub, The Rohm chuck has a split nut but it also incorporates the sleeves gear teeth. This means that the sleeve has to be pressed off the gear teeth towards the BACK of the chuck. The Nut/teeth unit is pulled apart and the other instructions apply.

With close examination it should be possible to decide which way to press. Don't do what I did and keep pressing until something gives. I killed the closing sleeve and had to make a new one!

I hope this is of some use to you.

Regards
Jim