Multitool-pencil Sharpener

Two of the most useful tools in every workshop are a pencil and a knife. They both have different functions but the knife is far more versatile as it can, among other things, serve as a pencil sharpener. In this Instructable, I am designing a pencil sharpener with a specific geometry in the handle to hold the pencil (like any pencil sharpener) and using the blade as the sharpening tool. This has the advantage of using the blade when it is folded making for a very safe use of the knife as a pencil sharpener. In this Instructable, I am sharing my models for one specific knife blade (OPINEL N°9) but you can design something similar for other blades

3D printer

Donor folding knife (the 3D models provided in this Instructables are specifically for an OPNIEL N°9 knife)

Here are the 3D files for the handle of a knife taking the blade from an OPINEL N°9. You can choose other knifes as a base but OPINELs have the advantage of strongly securing the blade when folded thanks to the mechanical part they call the "virole" in french. Strongly securing the blade in the folded position is a big advantage for this "pencil sharpener" application as sharpening the pencil does build quite a bit of effort on the blade

If you want to design something similar for a different blade, I found the most important consideration being that you do need a long enough portion of the blade do be straight just like you would find in a regular pencil sharpener.

For this knife, I have divided the handle into 3 parts, the part holding the pencil against the blade a part that just funnels the wood chips out and a spacer in between the 2 main handle parts. The pencil is held 15° off the blade to get a final angle for the pencil of 30° total. If you design your own model, you can then choose any angle.

My knife handle is split into 3 parts for ease of printing and a get a "nice" print quality out of my low budget 3D printer by minimizing supports but you can merge the 3 parts and print everything in one go. The metal parts are taken directly from the same donor knife that provided the blade.

OPINEL folding knife come in a wide variety of handles made traditionally from wood and with the correct setup, you could drill the original wood handle to add the pencil sharpening function but you do need the pencil guide part of the handle to tapper toward the blade otherwise the pencil bends away from the blade and is not sharpened.

This prototype is definitely not perfect as tolerances are way more important than I thought for a tool so apparently simple and you can improve gradually the design starting from What I have made here.