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I have a Dewalt DC725 cordless drill. I was recently drilling some holes through a plasterboard ceiling and I guess the drill has been jammed with plaster dust because the chuck is stuck in the fully open position.

I thought that if I removed the chuck I could replace it, but I can't get it off. I have removed the holding screw from inside, but as it is jammed, I can't tighten it around an allen key to unscrew the chuck.

Thanks a lot in advance!

Inside chuck

  • I cant remember if the chuck threads are left handed if the jaws are frozen it should not matter that you cant tighten the jaws. Try removing the chuck both clock wise and counter clockwise. if Lock tight was used on the threads when the chuck was installed a hair dryer can be helpful to heat the chuck and soften the lock-tight or other brands of thread locker. – Ed Beal Feb 9 '17 at 14:08
  • Chucks are screwed on normally (righty-tighty). Can't hurt to throw some penetrating oil in for loosening luck. One could use a strap wrench (or an improvised one with some flat webbing and a stick), but you're still working against the gears/motor of the drill, which could be very bad for the drill. – Aloysius Defenestrate Feb 10 '17 at 0:56
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Prop the drill upside down in a glass filled with warm muriatic acid for a few hours to dissolve the packed calcium sulfate, followed by a couple of whacks on the chuck with a hammer; repeat as necessary. Rinse and dry thoroughly afterwards as muriatic acid is a strong oxidizer that will quickly rust high-carbon steels if left metal surfaces exposed in air.

USE CAUTION as muriatic acid is actually hydrochloric acid and can burn you and your clothes; wear gloves and eye protection. You can find muriatic acid in the pool cleaning section of the big-box hardware stores.

I use this technique to dissolve impacted gypsum dust from my Dremel chucks.

  • While I'm not sure if this is good or bad advice (not my downvote, btw), I'd be concerned about safe use of the acid. Google is your friend for such things. I'd highlight the requirement to pour acid into water for dilution -- not the other way around. (And as a co-worker at a swimming pool discovered once, the bucket of "water" that he dumped into the chlorine could, in fact, be hydrochloric acid. Happily, he wasn't injured.) – Aloysius Defenestrate Feb 9 '17 at 18:31
  • Like I wrote, I use this method to unseize my Dremel chucks, which I use for carving the local (gypsum) alabaster. Opposing vise-grips aren't enough to loosen these things when that happens, so I've had to get inventive and find a non-standard solution. As for the downvote, I'd only expect that from someone too lazy to consider creative solutions, or submit a useful alternative! – Knob Scratcher Feb 9 '17 at 20:24
  • I would not use full strength mutatic (30% is my normal max) but other than this it is a good idea. The drill chuck is toast and this might clean it out enough to be usable after a good rinsing then oiling. I use muratic all the time for etching concrete and did not think of this. AAA ALWAYS ADD ACID or things can get messy. + – Ed Beal Feb 10 '17 at 0:47
  • Have the hydrochloric acid users tried 5 % acetic acid (ordinary white vinegar) or 20 % acetic acid and found it will not dissolve gypsum dust enough to free such a chuck? – Jim Stewart Feb 10 '17 at 11:55
  • Acetic acid works well to dissolve calcium carbonate but not calcium sulfate (gypsum, sheetrock). – Knob Scratcher Feb 10 '17 at 15:10
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Hopefully you have a rubber strap wrench - used for plumbing to prevent damage to pipes and sometimes for automotive to remove oil filters. Strap it on and try to give it quick sharp raps using something like a rubber or plastic mallet. If you just wrench by hand the chuck will just turn, but if you have the strap tight and pop it quickly, you may be able to break it loose with the inertia of the motor holding the spindle from moving.

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