The Forensic Disassembly of a Pencil Sharpener

Geek Culture

As many of you have heard me mention before, my wife is an elementary school teacher. Budgets being what they are in teaching these days, the best pencil sharpeners she ever saw in her classroom were the poorly-made plastic versions of those wonderful hand-crank ones we all knew growing up. Back then, they were probably all cast-iron, and engineered to withstand the rigors and abuses of school children. These days, well, I’ll just resort to the abbreviation: they’re all a POS.

So as an investment to help one aspect of her classroom management, we recently picked up a heavy-duty, office-grade electric pencil sharpener for her room. It was to be something built so solidly that it would stand up to her kids and bring things into balance.

Yeah, well…

It only took a couple weeks for one of her kids to sharpen a pencil down to a nib, and get it jammed inside the mechanism. So she brought to me, her geeky engineer husband. I had to take it apart to fix it, so I figured why not document the experience for posterity?


Turns out I didn’t really need to take the back casing off to solve the problem, but it was cool to look inside. Basically looks like a transformer and a variable-speed motor. And I like the fan down there for cooling. Also, upper right, you can see the three rotating grinder-heads that do the sharpening.


Front-on, with the pencil guide taken off and we can see the problem. There’s a little switch in the hole where the pencil goes. It’s a little strip of metal projecting into the hole, so that when a pencil is pushed inwards, the switch is pressed to the side and activates the motor (see the two wires coming out?). Trouble is, the student was able to poke the nub down past the switch, which popped back into the open position, making it impossible to just shake or fish the nub out. Anyone have any ideas how this little design flaw could be fixed?


With the switch plate taken off, the eraser end of the pencil nub was exposed, and easy to pull out. Mission accomplished!  I put everything back together, and it worked perfectly again. While this isn’t the most exciting project, it still helps reinforce the Maker idea that if you can’t open something up, you don’t really own it – and you should never be afraid to tinker! 

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