The usual advice is PETG, because it survives hot water. That is true and it is not the whole story.
The trade
| PLA | PETG | |
|---|---|---|
| Nozzle temperature | 190 to 220 C | 230 to 250 C |
| Bed temperature | 50 to 60 C | 70 to 90 C |
| Softens at about | 60 C | 80 to 85 C |
| Survives a dishwasher | No | Sometimes, top rack only |
| Blade rigidity | Stiff, cuts cleanly | Slightly flexible, can bow under pressure |
| Stringing between blade sections | Minimal | A real nuisance |
| Ease of printing thin tall walls | Easier | Harder |
| Brittleness | Snaps if dropped or twisted | Tougher, bends before breaking |
What actually decides it
Print PLA if you want the sharpest, most rigid blade and the least fuss, and you are happy to hand wash in warm water. This is most people, most of the time. A rigid blade cuts cold biscuit dough more cleanly than a flexible one.
Print PETG if the cutter is going into a commercial kitchen, is going to be washed constantly, or is going to live somewhere hot. A car in an Australian summer will exceed 60 C, which will deform a PLA cutter left on the seat.
The stringing problem is real
PETG oozes. On most prints that means a few wisps you pick off. On a cookie cutter with several separate blade sections, the nozzle travels between those sections on every single layer, so you get a web of fine strings across the gaps that has to be cleaned out of every one of them.
If you print PETG:
- Increase retraction distance and speed from your usual PETG profile
- Drop the nozzle temperature 5 C at a time until stringing reduces
- Turn Z hop off, since it makes PETG stringing worse, and accept a slightly higher risk of the nozzle catching the blade
The flexibility problem is also real
PETG is tougher, which people read as better. For a blade it is a mixed blessing. A 0.8 mm PETG blade 12.5 mm tall will flex slightly when you press it into firm dough, so the cut edge comes out very slightly rounded rather than crisp.
If you want PETG for the heat resistance and crisp cuts matter, print the blade 1 mm thick instead of 0.8 mm in the tool. You lose a little sharpness and gain the rigidity back.
What about the others
- PLA+ or Tough PLA is worth trying. It keeps PLA's printability and rigidity and is less brittle. The heat resistance is essentially the same as PLA, so it does not change the washing answer.
- ABS and ASA have better heat resistance again but need an enclosure, warp badly on a large flat flange, and bring their own health questions when printing. Not worth it for this.
- PP, polypropylene is what commercial cutters are made from and is genuinely dishwasher safe, but it is difficult to print and warps severely.
- Resin, SLA is a bad idea for anything touching food. Uncured resin is an irritant and full cure through a thick section is hard to verify.