Monday, July 12, 2010

Boston Pencil Sharpener Model 18 Large Gear

If you found this blog then chances are you have a Boston Electric Pencil Sharpener - Model 18, and let me guess, it was working great for years until one day, the large gear broke.

This happened to my Dad. I had no clue why he wanted to repair it...why not just buy a new one? After seeing how sturdy this sharpener was built and what a perfect point it makes, I now 'get' why he doesn't want a newer different one.

I searched for parts and no luck. I did have plenty of luck finding other folks online who are in the same boat. Their large gear is broken too... some have even purchased new sharpeners but would still rather have their Model 18 working again.

I will for now spare the boring details about all the experimentation it has taken (and small investment!) but the bottom line is, I was able to reproduce the gear. The copy is made of tougher material, and I am able to make spares as-needed.

The image shown is a pair of repro gears, arranged to show the front and back details of the part. On the front side of the part (right side of photo), the mounting hole for the shaft is a detailed copy of the original. The gear will fit on to the shaft assembly just as the old one did. On the rear side of the part (shown on left side of photo), the center hub spacer and edge detail match the original.

These are working prototypes and have some minor flashing on the back edge of the gear. That does not affect operation and I am working to elminate that. I am re-working the mold to eliminate air bubbles, but that has been minor and non-critical to operation also. These prototypes are made of stronger material than the original and will be available for about 12 dollars.


The next phase of this project is to continue improvements on the casting process and then work on replacements for Boston Model 17 and Boston Model 19 gears.


  1. I would buy one! If you finished product please post how to order. I have model 18.


  2. I would purchase one for my Model 18. How soon can you have one ready?

  3. add me, I like to buy one too

  4. Add me too! I just found a model 18 and love it.

  5. This happened to my Derwent superpoint battery operated helical pencil sharpener (they replaced it, but I just have to replace the big gear similar too yours) in my original first purchace broken model, its a shame to go to waist.

  6. I am in desperate need of a gear! PLEASE help me get one!!!!!!!!!

  7. Being that this original post was from 2010, can I assume that the quirks and such have been all worked out and that these are available? And the cost? Our model 18 gear broke into about 10 pieces last week! ahhhh!!!