Broken drill, how do I get the chuck off?

[LCHIEN]

Got a cheap HF pneumatic drill, that leaks air internally and lost torque and speed. As it was but about 10 bucks its not worth the time to fix it.

I was going to steal its 3/8" chuck before tossing it, but not sure how to get it off.

The chuck is marked 3/8-24 UNF. I assume its got a 3/8" Stud or socket with which its connected to the drill shaft. LH or RH?

I opened the jaws and looked down inside, I see a screw head. I removed the screw (and its a L:H threaded screw!) but the chuck doesn't come off.
I can turn the chuck itself but it just turns the motor internal to the drill so I can't lock the motor to unthread the chuck off it.

Any suggestions?

I assume the drill shaft end looks like this, the big thread being the 3/8"-24 UNF.

How do I secure the motor shaft so I can unscrew the chuck?

[mpc]

This is where "impact" may help. Since you have the internal screw removed (the reverse-threaded screw) you're half way done. Next step is to put something into the chuck that lets you "whack" it - sudden shock will help get it to unscrew when you can't hold the motor. An allen wrench (biggest one that'll fit into the chuck jaws) works well: insert the short end into the chuck and lock it down. If the drill has a gearbox (high/low speeds) set it to the low speed to get slightly more resistance from the motor and gearbox. If it has a torque limiting clutch, set it to the highest torque position. Lay the drill down, turn the chunk so the allen wrench is horizontal. Whack it so it wants to unscrew the chuck in the normal counter-clockwise direction. Typically, this means the allen wrench is at 9 o'clock as you face the chuck jaws... whack the allen wrench straight down with a hammer.

You might be able to put the allen wrench into a solid vise to hold the chuck and run the drill backwards.

mpc