3D Printing and Additive Manufacturing
How printers build parts layer by layer: processes and hardware, slicer settings, materials, design rules, strength and fits, calibration, finishing and troubleshooting, with worked examples.
Additive manufacturing builds a part by adding material, layer by layer, directly from a 3D model. It suits one-offs, prototypes, jigs and fixtures, and shapes that are hard to machine, and it has made small-scale manufacturing available to anyone with a desk. It is not the best way to make thousands of identical parts, and a printed plastic part is weaker than the same shape molded or machined, so the design has to respect the process. Most workshop printing is FDM (fused deposition modeling, also called FFF): a heated nozzle lays down melted plastic filament. This guide covers FDM in depth, with resin and powder processes alongside, from the hardware and slicer settings through materials, design rules, strength and fits, calibration, finishing and troubleshooting.
Start here: what do you need?
| I need to… | Go to |
|---|---|
| understand the processes and how a model becomes a part | Processes and Workflow |
| choose or understand a printer: motion system, extruder, hotend, bed, firmware | FDM Printer Hardware |
| set layer height, walls, infill, speed and supports, or estimate print time and cost | Slicer Settings and Print Quality |
| pick a filament, or find the print and drying temperatures | Filament Materials |
| design a part that prints well: orientation, overhangs, holes, threads, snap fits | Designing for 3D Printing |
| know how strong a printed part is, or size holes and fits that actually assemble | Strength, Accuracy and Fits |
| use a resin printer, or order SLS or MJF nylon parts from a service | Resin and Powder Processes |
| level the bed, set the first layer, tune flow and temperature, or maintain the printer | Calibration and Maintenance |
| sand, fill, paint, smooth, anneal or glue a printed part | Post-processing and Finishing |
| fix a failed print, or make the shop safe for printing | Troubleshooting and Safety |
A suggested order
If you are new to printing, read the first three pages to get a good first print, then the materials and design pages. The strength and calibration pages are what separate a printer that makes models from one that makes working parts.
- Processes and Workflow: The additive processes compared, and the path from a CAD model through the slicer to a finished part.
- FDM Printer Hardware: Motion systems, extruders, hotends, beds, nozzles and firmware: what each part does and what to look for.
- Slicer Settings and Print Quality: Layer height, walls, infill, speed, flow limits, cooling, retraction, supports and adhesion, with print time and cost worked out.
- Filament Materials: PLA, PETG, ABS, ASA, nylon, TPU, polycarbonate and filled filaments: temperatures, properties, drying and choosing one.
- Designing for 3D Printing: Orientation, overhangs, bridges, minimum features, holes, threads and inserts, snap fits and splitting large parts.
- Strength, Accuracy and Fits: Why printed parts are anisotropic, how walls and infill set stiffness, shrinkage, dimensional accuracy and clearance for fits.
- Resin and Powder Processes: Resin (MSLA) and powder (SLS, MJF) printing: how they work, settings, washing and curing, and what they cost.
- Calibration and Maintenance: Bed leveling and the first layer, e-steps, flow, temperature and retraction tuning, input shaping and routine upkeep.
- Post-processing and Finishing: Support removal, sanding, filling, painting, smoothing, annealing, and joining printed parts.
- Troubleshooting and Safety: A symptom-to-cause guide to print failures, and the heat, fire, fume and resin hazards to manage.
Quick reference: numbers worth remembering
| Quantity | Typical value (0.4 mm nozzle, PLA) | Page |
|---|---|---|
| Layer height | 0.12 mm fine, 0.2 mm standard, 0.28 mm draft; 25 % to 75 % of the nozzle | Slicer Settings and Print Quality |
| Line width | 0.4 to 0.5 mm | Slicer Settings and Print Quality |
| Volumetric flow | Q = width × height × speed; a standard hotend melts about 10 to 15 mm³/s | Slicer Settings and Print Quality |
| Filament | 1.75 mm: 1 kg of PLA is about 335 m; PLA density 1.24 g/cm³ | Slicer Settings and Print Quality |
| Nozzle temperature | PLA 190 to 220 °C; PETG 220 to 250 °C; ABS 230 to 260 °C | Filament Materials |
| Overhang limit | About 45° from vertical without support | Designing for 3D Printing |
| Minimum wall | Two line widths: about 0.8 to 1.0 mm | Designing for 3D Printing |
| Holes | Print 0.1 to 0.3 mm undersize; drill or ream when accuracy matters | Strength, Accuracy and Fits |
| Shrinkage | PLA about 0.3 %, ABS about 0.6 %, nylon about 1.5 % | Strength, Accuracy and Fits |
| Strength across layers | Often 30 to 70 % of the strength along the layers | Strength, Accuracy and Fits |
Which process and material?
| Need | Good choice | Because |
|---|---|---|
| Cheap prototype, display model | FDM in PLA | Cheapest, easiest, no enclosure; soft above about 55 to 60 °C |
| Functional bracket or housing | FDM in PETG, or nylon / filled nylon | Tougher than PLA, better temperature and chemical resistance |
| Outdoor or hot-car part | ASA, or PETG | ASA resists sunlight and heat; needs an enclosure |
| Seal, bumper, grip | TPU | Flexible; print slowly |
| Fine detail, small smooth parts | Resin (MSLA) | Layers of 0.025 to 0.1 mm; brittle, messy to finish |
| Strong small-batch nylon parts | SLS or MJF from a service | No supports, isotropic strength; bought rather than owned |
| Thousands of identical parts | Injection molding or machining | Lower cost per part and better properties at volume |
Calculators and related guides
- 3D Printing Tolerancing Guide: clearances and hole compensation for fits that assemble.
- Bolt Torque and Thread Engagement Tool: fasteners into printed parts and inserts.
- Fits and Tolerances and GD&T: how fits and tolerances are specified on drawings.
- Structures and Strength of Materials: the stress, beam and fatigue methods used to check a printed part.
- CNC Machining and Prototyping Techniques: choosing between printing, machining, laser cutting and mock-ups.
- Electronics Fundamentals: heaters, thermistors, stepper drivers and power supplies inside the printer.
Safety
- Hot parts and fire. The nozzle runs above 200 °C and the bed up to 110 °C. Keep thermal runaway protection enabled, do not leave a printer running unattended without a smoke detector in the room, and check heater and bed connectors for heat damage.
- Fumes and particles. Printing emits ultrafine particles, and ABS and ASA release styrene. Ventilate or filter the room or enclosure, and keep printers out of bedrooms.
- Resin. Liquid resin irritates skin and can sensitize it. Use nitrile gloves, eye protection and ventilation, and never pour resin or wash fluid down a drain.
- Powder and tools. Nylon powder needs extraction and respiratory protection, and knives, scrapers and sanding need eye protection. The details are in Troubleshooting and Safety and Workshop Safety.
FAQ
Which filament should I start with?
PLA. It prints at a low temperature, barely warps, needs no enclosure and gives good surface quality. Move to PETG for tougher or outdoor parts, and to ABS, ASA or nylon when you need heat resistance or toughness and have an enclosed printer. See Filament Materials.
How strong is a 3D-printed part?
It depends on the plastic, the orientation, the number of walls and the temperature. Printed parts are weaker than molded ones, and much weaker across the layers than along them. More walls and the right orientation help far more than more infill: see Strength, Accuracy and Fits.
Why does my print take longer than the slicer says?
Slicer estimates assume the machine reaches its set speeds, but short moves, corners, retractions and travel limit the real speed. A 30 to 100 percent increase over the estimate is common, and Slicer Settings and Print Quality shows where the time goes.
Do I need an enclosure?
For PLA and PETG, usually not. For ABS, ASA, nylon and polycarbonate, yes: it keeps the part warm to prevent warping and cracks, and it contains fumes, which you should then filter or vent.
Where did the old 3D Printing sections go?
Everything from the old single page is now spread across the guide with much more detail: processes in Processes and Workflow, speed and flow in Slicer Settings and Print Quality, filaments in Filament Materials, design rules in Designing for 3D Printing, and calibration and troubleshooting on their own pages.
References
- ISO/ASTM 52900, Additive manufacturing: general principles and terminology.
- Gibson, I., Rosen, D. and Stucker, B., Additive Manufacturing Technologies, Springer.
- Filament makers’ technical data sheets (for example Prusa, Polymaker, Bambu Lab, Ultimaker, eSun) for temperatures and properties.
- Hotend manufacturers’ published volumetric flow figures (for example E3D, Slice Engineering, Bondtech).
Last reviewed: October 2026. Speeds, temperatures and tolerances are typical: test on your own machine and material, and treat printed parts as unproven until tested.