Espresso portafilter paper filter cutter (multiple diameters)

Update 12/18/23: I have found that using a square of shelf gripper, liner, foam under the cutter prevents the base from rotating. See third photo. Press firmly on the spindle with one hand while rotating the blades with the other. Cut two filters at a time. If it starts to bind up, switch blades.

Update 03/17/23: Designs for other filter diameters attached as ZIP files. These files are mathematically accurate, but untested. If a print doesn't work, post a comment (without sharing a low star rating please) and I can make adjustments. 

If you don't know which size(s) you need, check out the images on the Good Brothers Coffee product page. If you don't have access to a 3D printer, consider buying from them.

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Motivated by two Lance Hedrick videos (comparing $200 baskets and Gagné talking about paper filters), I wanted to try adding a paper filter to my VST portafilter basket.

According to Reddit and Good Brothers Coffee, a 55mm circle* was the right size for my 58mm VST 18g ridgeless basket. Unfortunately, the circle cutters I found got poor reviews and I wasn’t ready to order 100+ precut … so I designed and printed my own solution.

This model cleanly cuts at least three (3) AeroPress filters at one time. Here's a video of an earlier prototype in use.

*While the 3D model is designed mathematically to be 55mm, the cut filter is actually closer to 54.5mm, which is a better fit for my basket. I tested 54mm, 54.5mm and 55mm filters. All performed identically.

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I printed with a 0.4 nozzle and PETG. Printing with PLA should be fine, too.

• I had cleaner prints with the Classic Perimeter Generator. However, Arachne works as well.
• 0.20mm Quality print setting
• 20% rectilinear fill
• 2 perimeters
• No supports needed

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Assembly requires TWO (2) of each item below. The M3 hardware was left over from my Prusa MK3S+ kit build:

• Xacto #11 blades
• M3nS square nuts
• M3 screw bolts (12mm length or shorter)
• M3 flat washers
• Sandpaper (optional)

1. You may need to sand off burrs and defects in order to get a clean fit and smooth rotation.
2. Insert square nut into slot. If needed, use a paper clip to push deeper.
3. Place Xacto blade onto oval notch. The blade should point toward the wider end and with the flat side placed against the flat ridge (see photo).
4. Insert bolt into flat washer and screw into square nut. Do not over tighten as it will cause the blade to rotate.
5. Repeat on other side.

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Instructions for use:

1. Watch video.
2. Separate pieces. Place cutter on surface with blades facing up. BE CAREFUL WITH EXPOSED BLADES. I ASSUME NO RESPONSIBILITY FOR INJURY.
3. Place 1, 2 or 3 AeroPress filters into base (attempting to cut more filters may jam the blade).
4. Place center cutter into base with blades facing down.
5. Insert spindle into cutter. Placing the rougher top side (that was the last surface extruded) against the filter worked better for grip.
6. With one hand hold the base and press down firmly on the center spindle. This is a critical step as it prevents the filters from rotating.
7. Gently press down on the cutter and rotate counter-clockwise.
8. Remove spindle.
9. Remove cutter. Place cutter on surface with blades facing up. BE CAREFUL WITH EXPOSED BLADES.
10. Remove and separate cut filters.