I'm trying to remove the metal box that holds a bathroom exhaust fan into the ceiling. I've got all the wood screws out but there are 2 sheet metal screws that appear to connect the box to the duct to the outside. The problem is the screw heads are inside the duct and I can't access them. All I can see are the threads. Is there a way to remove the screws from the threaded end? I've tried cutting them off with a hacksaw and a cold chisel. I also tried pounding them out with a hammer.

  • Do you have room to reach into the duct and use a stubby screwdriver or right angle drill?
    – Doresoom
    Jan 18, 2015 at 4:35
  • No, the reason I'm doing this is the vent flap is jammed so I can't get into the duct at all. The other end is too far away. To clarify - the hacksaw and cold chisel didn't even make a mark. (Maybe I used the wrong kind?)
    – StepByStep
    Jan 18, 2015 at 16:37
  • By the way, a number of these answers were very useful, but I'm not allowed to give up votes yet.
    – StepByStep
    Jan 19, 2015 at 20:37

5 Answers 5


If there's enough sticking out that you can grab on to, a pair of locking pliers would likely help turn it but it will be hard to fully unthread since there will come a point where the pliers don't have enough to grip on to. If you're lucky, you might get enough clearance to cut it or turn it from another part of the screw.

Another option is to simply drill it out and then tap new, slightly larger threads to use with a larger screw when re-installing.


You could try grasping the screw's threaded end with a pair of pliers and rotating. If there's not enough friction, you could try sandwiching the screw between a piece of scrap rubber or something similarly tacky or sticky.

  • Tried that but the screws were too short to get a grip.
    – StepByStep
    Jan 19, 2015 at 20:36

this would probably have been easier if you hadn't hack-sawed off the exposed threaded ends….:D

Now that that's done, I expect your best bet is to try to 'tap' them w/ a screw-removal bit. They're reverse-threaded drill bits made for drilling into the shaft of broken-off screws. The challenge will being able to push hard enough against the screw to get it to bite.

Alternatively, get a set of metal sheers and snip the sheet metal of the fan.


The easiest way to do something like this is with a diamond hole saw, 1/4" maybe.

Sheet metal screws are da ebil. Do not attempt to negotiate with them.


I finally figured it out. I used a Fein MultiMaster to cut the screws down to the sheet metal. One of them helpfully fell out after that. For the other I tried a nail punch but it was stuck too well. So I used a crowbar between the outside of the box and the vent it was attached to. That did it. Thanks for all the answers.

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