Folding scalpel knife

Small and light folding handle for disposable scalpel blade. Designed specifically for blades no. 24. When closed, the edge of the blade is safely hidden in the handle.

I designed it s an ultralight cutting tool for a backpacking first aid / repair kit, but now I'm using it around the workshop too - it works great for trimming 3D prints and many other light-duty cutting tasks.

The two parts are printed separately and snap together. When printed right, the pivot provides just the right resistance for safe opening / closing. Moreover, there's a small tab on the handle that locks the blade in the closed position, and the blade has to be lifted a bit when opening (if you don't want this feature, cut this tab away).

I've found that the slits on the blades from different manufacturers are not exactly the same. The stem labeled 'normal' should work in most cases but if it's too wide, try the 'narrow' version. I added also an ‘extra narrow’ version you can try if the ‘narrow’ one still does not fit.

Be careful, the blades are super sharp! (It's a good idea to hold the blade with pliers when inserting it.)

Edit Sep 3 2023: Here is some advice if the blade does not fit. First, I added even narrower version of the stem. Second, there is, another factor affecting the fit - if the overhang on the groove for the blade does not print well, there may not be enough space for the blade. In such case, it helps to clean the groove using another tool before inserting the blade. If the blade does not fit lengthwise (i.e. the tab on the blade does not lock in place), you can shorten the stem a little bit by sanding down the tip.

Edit Jan 20 2024: I added an earlier version of the design which looks more like a conventional folding knife. It does, however, require a rivet or screw to be used as a joint.

Print Settings

Printer: Prusa MINI

Rafts:  No

Supports: No

Nozzle: 0.4 mm

Layer height: 0.2 mm (the handle) / 0.1 mm (the blade stem)

Infill: 100%

Filament: PETG 

Notes: Designed for PETG, printed with 0.4 mm nozzle. It's important to have good layer adhesion, otherwise the pivot may break off. The handle can be printed with 0.2 mm layers. The blade stem looks and better if printed with finer layers, and it may also fit the blade better (I'd recommend 0.1 mm).