Summary

A DIY sharpener with perfect performance, exchangeable blade and as cheap as 0.28€.

Designed for 4-segments of a 9mm blade.

Print Settings

Printer Brand:

Prusa

                                            <p class="detail-setting printer"><strong>Printer: </strong>                     <div><p>I3 MK3S</p></div></p>                                                                                <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>0.2</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>15%</p></div></p>                                                    <strong>Filament:</strong> Noname PETG                Black                    <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>Use a brim!</p></div>

Post-Printing

remove the brim
drill tout he hole for the backside of the blade with a 3mm drill
remove any bur at the blade's entry slot.
Insert the blade with proper pliers

How I Designed This

Design example with Blender 2.80

The Blade

I measured a commonly available 9mm brake off knife blade:

It's segments are 5mm wide
the blade is 9mm high
0.4mm thick and
the edge is 1.2mm high (equals to 2x10°).
4 segements = 20mm are used for one sharpener

The Cone

The cone has a ratio of 2:1 (length:diameter).

The Placement of the Blade

The blade sits at an angle of 13° to the tangent of the cone and is set 0.2mm dpwmwards at the cones widest location. At the tip of the cone, the blade dips about further 0.2mm (it is tilted 1°) towards the cone axis. This was needed to get a good sharpening performance.

Pencil Sharpener (Bleistift Spitzer)