About this video
Day 2: from 3D model to printer instructions
This is day 2, part 1 of PrintPal's learn 3D printing in 7 days series. On day 1 you ran your first print and learned how the printer works. Today: what the slicer actually does, and which filament to choose.
What is slicing?
Your printer can't read a 3D model directly. The slicer (Bambu Studio, OrcaSlicer, Creality Print, PrusaSlicer, Cura) cuts the model into layers and turns it into G-code: step-by-step instructions the printer follows. G-code tells the printer:
- where the print head moves, line by line
- how hot the nozzle and bed should be
- how much to turn the extruder gear, which sets how much plastic comes out
- fan speeds, print speeds and much more
Why prints aren't solid: walls and infill
Filling the whole model with plastic would waste filament and hours of print time. Instead the slicer prints the outline (walls plus top and bottom layers) and fills the inside with infill, a lightweight internal pattern that supports the structure. Most slicers default to around 15% infill, which is plenty for decorative prints. Functional parts usually get more walls and more infill.
PLA vs PETG
| PLA | PETG | |
|---|---|---|
| Ease of printing | Easiest, the best first filament | Easy, but strings more |
| Nozzle temperature (typical) | 190–220 °C | 230–250 °C |
| Toughness | Stiff, can snap | Tougher, bends before it breaks |
| Heat and outdoor use | Softens in heat, doesn't last long outside | Better outdoors and in heat |
| Moisture | Low concern | Absorbs moisture from the air, so dry it |
Wet PETG strings and bubbles. Work out drying time with the filament drying calculator, and see how to fix stringing. Not sure which material fits your project? The free filament finder recommends one based on your answers.
FAQ
What is G-code?
The text file of machine instructions the slicer creates: moves, temperatures, extrusion amounts and fan speeds, one line per step.
How much infill should I use?
About 15% for most prints. Use more for parts that carry load, and add walls first, because walls add more strength per gram than infill.
Should a beginner use PLA or PETG?
Start with PLA. Switch to PETG when a part needs to survive heat, sunlight or impact.
