7 persistent myths about 3D printing

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Plenty of half-truths circulate about 3D printing. Some date from the time of the first hype, others are simply passed on in forums and comments. Here are seven myths that keep coming up, and what is actually behind them.

Myth 1: “You can print anything with a 3D printer”

A home printer can do a lot, but by no means everything. An FDM printer processes plastics that soften when heated. Metal, glass or ceramic parts in final quality are made on other, mostly industrial machines.

On top of that come limits in the printing itself: the build volume limits the size, steep overhangs need supports, and printed parts are weaker between the layers than along the layers. A part that fits in theory can break in practice at exactly this point. What can sensibly be printed is explained in What is 3D printing?.

Myth 2: “More infill makes a part stronger”

Only partly true. More infill does make a part somewhat stronger, but beyond a certain point every additional per cent brings hardly anything, while costing time and material. The outer walls carry most of the load. The engineer and YouTuber Stefan Hermann (CNC Kitchen) also concludes in his tests that more wall thickness usually brings more strength than more infill.

A part with four walls and 20 % infill is therefore often stronger than one with two walls and 50 %. You will find specific values in Setting infill.

Myth 3: “I can throw PLA on the compost”

PLA is often advertised as biodegradable. That is not wrong, but it is incomplete. PLA only breaks down reliably under industrial conditions, meaning controlled moisture and temperatures around 60 °C over weeks to months. According to NABU, testing to the standard EN 13432 takes place at around 60 °C, and according to the testing laboratory Measurlabs, the associated test standard ISO 14855 is usually run at 58 °C. A garden compost heap does not get hot enough for that. There, a PLA print lies for a very long time without much happening.

PLA does not belong in the organic waste bin either: many composting plants cannot process bioplastics to the standard and sort them out. Where leftovers belong instead is explained in Disposing of and recycling filament. More on the material in Printing PLA.

Myth 4: “3D prints are food-safe”

A filament can be approved as a raw material for food contact. The printed part is far from automatically so. The Prusa Knowledge Base gives several reasons:

• Food residue settles in the grooves between the layers, and bacteria can multiply there. This can hardly be cleaned thoroughly.
• Washing-up liquid can also lodge in the grooves.
• The usual brass nozzle wears down, and the abrasion ends up in the print.
• Dyes and additives in the filament are often not tested for food.

Prusa explicitly advises against using prints as food containers. What a declaration of conformity from the filament manufacturer means and what printed parts are still good for in the kitchen is explained in Food-safe printing.

Myth 5: “An expensive printer automatically makes better prints”

A more expensive printer can save you a lot of work: automatic calibration, enclosed housing, multi-colour system, higher speed. But print quality depends just as much on things that every printer needs: a clean print bed, suitable temperature, dry filament and sensible slicer settings.

A well-tuned cheap printer often delivers better results than an expensive machine with damp filament and wrong settings. How to set up your printer properly is explained in Calibrating your printer.

Myth 6: “3D printers are toxic” or “completely harmless”

Both fall short. Studies by UL Chemical Insights found over 200 different volatile organic compounds (VOCs) in the emissions of FDM printers, as well as ultrafine particles that can reach deep into the lungs. How much is produced depends heavily on the material and temperature: ABS gives off significantly more than PLA.

Panic is still not called for. If you ventilate regularly, do not sleep right next to a running printer and use an enclosure with a filter for ABS, ASA or nylon, you reduce the exposure significantly. Which filters really help is explained in Enclosures and air filters.

Myth 7: “Without CAD skills you do not need a 3D printer”

Many people print for years without ever designing a model themselves. The big platforms hold millions of ready-made files, many of them free, often already with suitable print settings. Where to find good models is explained in Finding models.

And if you do want to design something yourself: simple brackets or spare parts can be learned in an afternoon with free programs in the browser. An overview is given in Learning to model.

In brief

Continue with: The history of 3D printing.