Used my little metal cutting bandsaw to chop off the chuck end (worked marvelously, so much easier than expected). Didn't want to destroy the chuck, but I have zero use for a mud mixer with a proper chuck. I want the rest of it!Notice you can see at least four threads of the chuck going down into the spindle area. What is that? Is the spindle and/or the chuck threading tapered? Even if it is, why waste so many threads. I'll probably find out after removing it.
Squirted some WD-40 into the spindle area several times, and on the other side.
Secured a large vice grip to the chuck. Put the drill in reverse, laid it on the ground, and stood on it (160 pounds). Pressed the trigger and the thing jumped up a bit before the electric torque limiter apparently kicked in. Repeated that about 10 times. Damn chuck won't come off. So now I will open it up, clean all the grease off of it, and remove the spindle part. See how it's put together. At that point, maybe I'll have a better access to the spindle so that the chuck can be wrenched off.
You think maybe they use some kind of cotter key/pin to prevent the chuck from unscrewing? Seems weird. But maybe there is another press fit at the base of the chuck. I thought the press fit was just on the end. Suppose I could use something better than WD-40 for unfreezing the chuck. Or maybe a torch will work. Will see. It will come off without damaging the rest. Yes it will.