Meet FOUTIK V1 (FOlding UTI-lity Knife, how lazy 😅)
All handling operations can be performed while wearing thin gloves: open, close, blade change.
The Fusion 360 CAD model, STEP and 3 MF files are all on Github
Happy printing to all !
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Design
Available in 2 versions, a Basic one and one with glued-on Inlays:
The Basic design consists in 2 simple parts:
Printing
Settings for a 0.4mm nozzle on Bambu P1S, PLA or ABS:
- 0.95 flow, 0.2 layer height, 0.45 width
- 2 walls, 2 top & bottom layers
- concentric solid infill
- 100% concentric sparse infill
- no brim if using Bambu basic PLA / ABS (5mm outer brim otherwise)
- print By Object if using different colors, to reduce print time and waste
- support: tree auto, organic, 33° angle, build plate only
The knife can be printed in place when using Bambu basic PLA or ABS filament that doesn't ooze or swell much, and isn't very hygroscopic.
Other filaments, like PETG / PCTG, or matte / CF / GF / silver / metallic PLA or ABS, usually don't do as well with tight tolerances between surfaces. That results into fusing the 2 parts together. Trust me, I tried: CCTree, YXPolyer, 3D-Fuel PCTG, Bambu PETG, Polymaker metallic filament, etc. That just resulted in about doubling the plastic waste of all Colorado... 😅
To print in place or not, just pick in the Objects tab the knife version needed:
The version with inlays comes with 3 step files: body+head, left inlay, right inlay. Of course, you'll want first to change the CAD model with your own text / logos. To change the color of the text and logos, make sure to Split into Parts the 2 inlay objects first. Or just apply embossed text in the slicer itself.
Assembly
For the best result, it is very important to let the printed parts FULLY cool down before starting the assembly process. Even when cool to the touch parts of the melted filament will still be in a partial plastic state for several minutes after cooling down to ambient.
If not fully solid, when snapping loose the blade and the open/close fingers, they will acquire a slight but permanent deformation with lower elastic modulus. Waiting an additional ~30' after cool down will help ensure they remain straight and stiff, satisfyingly snapping back into place when using the knife.
Step 1 - remove brim & supports
Remove the 2 tiny supports:
Using a large screwdriver blade or chisel, gently pry apart each finger by rotating the blade, until it separates. Should hear a sharp sound when that happens (requires fully cooled down parts).
Step 3 - break loose the pivot (only if printed in place)
Very gently try to separate the pivot flanges, on both sides of the knife (requires fully cooled down parts). Work your way along the flanges. Also, sometimes just wiggling the blade head sideways is enough to break the bonds.
If the flanges are too stuck together or break during the process, consider the following:
- reduce the filament flow by 5% and try again (ex: 0.95 flow → 0.9)
- make sure the filament is dry (otherwise bubbles will bridge the space between surfaces)
- use a filament that is less sticky or swells less, like Bambu basic PLA / ABS (FYI: had no luck with CCTree and YXPolyer basic ABS)
- select and print the separated body and head, not the print-in-place ones
Step 4 - glue the inlays on (optional)
Handling
Opening the knife takes 2 hands. With one hand pull on the lever ears to disengage its lock on the head, by catching the lever ears between the thumb and the middle finger while pushing on the body with the index finger. Then with the other hand pull on the head ears to rotate the head open.
Closing the knife takes just 1 hand. Simply pull on the lever ears and push on the head to rotate and close it.
To change the blade, pull on the blade lever.
And now not only can I afford losing a box cutter every day, but they also serve as personalized gifts / memories for other construction crew members, thanks to the inlays. Example: "Glad you're leaving, Tom !". Sweet... 😅
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