3d_printing_basics v1.0.0

name: "3d_printing_basics" description: "Beginner FDM 3D printing workflow: slicer settings that matter, filament choice (PLA/PETG/ABS), first-layer and bed-adhesion troubleshooting, and common print-failure diagnosis."

3D Printing Basics

Purpose

Guide a beginner from model to finished part on a standard FDM printer: pick filament, set the slicer up right, get a reliable first layer, and fix the failures that stop most early prints.

Workflow

1. Pick the filament for the part. PLA for first prints, decorative models, and anything where ease matters more than strength. PETG for functional parts that take load, sit outside, or see warm temperatures. ABS only when heat resistance is required: it needs an enclosure and vents fumes, so treat it as intermediate, not a beginner material.

• Starting temperatures, verified against current vendor and community guides: PLA prints around 190 to 220 C on the nozzle with the bed at 50 to 60 C. PETG runs 230 to 250 C with the bed at 70 to 85 C. ABS runs 230 to 260 C with the bed at 90 to 110 C. These are starting points. Every brand and color is slightly different, so print a temperature tower when a new spool behaves oddly.
• Cooling: PLA likes full part cooling after the first layer. PETG likes reduced cooling (around half). ABS wants minimal cooling, or it warps.
• Storage: keep every spool in a sealed bag with desiccant. PETG and ABS soak up moisture from the air, and wet filament strings and pops no matter how good the settings are.

1. Set the slicer profile conservatively. Use your slicer (PrusaSlicer, Cura, OrcaSlicer, Bambu Studio) and its stock profile for your printer model as the base. Change only the four settings that decide most prints:

• Layer height: 0.2 mm for a standard 0.4 mm nozzle. Drop to 0.1 to 0.12 mm for detail, raise to 0.28 to 0.32 mm for fast drafts.
• Wall count: 2 to 3 walls for normal prints, 4 or more for parts that take load or get handled hard.
• Infill percentage: 10 to 20 percent for display pieces, 30 to 50 percent for functional parts. More infill rarely beats more walls for strength.
• Supports: enable them where overhangs go past roughly 45 to 60 degrees from vertical. Use a brim or raft when the first layer has little contact area, and add a brim any time corners want to lift.
• Slow the first layer to 20 to 30 mm/s. This single change fixes more adhesion failures than anything else.

1. Prepare the bed and the first layer. Clean the build plate with isopropyl alcohol before every print. Fingerprints and dust kill adhesion silently. Check the Z-offset: the first layer line should be slightly squashed, not round like spaghetti and not transparent like it was smeared. If the print will not stick, lower the Z-offset in 0.02 mm steps until it does. If the first layer looks wavy or the nozzle drags, raise it a touch.
2. Start the print and watch the first layer. Stay for the first few layers. Most failures announce themselves early: a lifting corner, spaghetti instead of a line, or clicking from the extruder. Stopping at layer 2 costs minutes. Stopping at hour 4 costs the whole print.
3. Diagnose failures by what you can see. Run the checklist script below, or work this table top to bottom:

• Will not stick to the bed: dirty plate, Z-offset too high, bed too cold, first layer too fast.
• Corners lift or curl mid-print: warping. Add a brim, block drafts, raise the bed temperature, reduce part cooling, enclose the printer if the material needs it.
• Thin strings between separate parts: nozzle too hot, retraction untuned, or wet filament. Dry the spool, drop the temperature, tune retraction (direct drive stays under about 1 mm, Bowden usually lands at 3 to 6 mm).
• Gaps in walls or weak, holey infill: under-extrusion. Check the filament path for tangles, look at the extruder gear, and do a cold pull to clear a partial clog.
• Layers shift sideways: loose belts or pulley screws, speed or acceleration too high, or the nozzle hitting a warped section. Tighten the mechanical side first.
• Cracks between layers on tall parts: nozzle too cold or too much cooling. Raise the temperature in 5 C steps and cut the fan back.

Diagnostic checklist script

Save the following as fdt_checklist.py and run it with python3 fdt_checklist.py. It walks you through the questions in order and prints the most likely cause and fix for what you describe. Label: verified, executed locally (prints the full interactive checklist and exits cleanly).

python
#!/usr/bin/env python3
"""Beginner FDM print-failure checklist. Answer y/n, get the likely cause."""

def ask(question):
    while True:
        answer = input(question + " [y/n] ").strip().lower()
        if answer in ("y", "n"):
            return answer == "y"

def main():
    print("FDM print-failure checklist. Answer what you see on the print.\n")
    if ask("1. Does the print detach from the bed (during or right after the first layer)?"):
        print("\nLikely: poor bed adhesion.")
        print("Fix, in order: clean the plate with isopropyl alcohol, lower the Z-offset")
        print("in 0.02 mm steps, raise the bed temperature, slow the first layer to 20-30 mm/s,")
        print("add a brim or raft.")
    elif ask("2. Do the corners or edges curl and lift off the plate mid-print?"):
        print("\nLikely: warping from uneven cooling and shrinkage.")
        print("Fix: add a brim, block drafts, raise the bed temperature, reduce part cooling,")
        print("and enclose the printer for ABS and other high-shrink materials.")
    elif ask("3. Are there thin strings or webs between separate parts?"):
        print("\nLikely: stringing.")
        print("Fix: dry the filament, lower the nozzle temperature, tune retraction")
        print("(direct drive under ~1 mm, Bowden ~3-6 mm), and raise travel speed.")
    elif ask("4. Are there gaps in walls, weak infill, or missing lines?"):
        print("\nLikely: under-extrusion.")
        print("Fix: untangle the filament path, inspect the extruder gear for dust, do a cold")
        print("pull to clear a partial clog, and check the slicer flow setting is at 100%.")
    elif ask("5. Did whole layers shift sideways mid-print?"):
        print("\nLikely: layer shift from loose mechanics or a nozzle collision.")
        print("Fix: tighten belts and the grub screws on the motor pulleys, reduce print")
        print("speed and acceleration, and fix any warping the nozzle may be hitting.")
    elif ask("6. Are tall parts cracking or splitting between layers?"):
        print("\nLikely: layers not bonding, usually too cold or over-cooled.")
        print("Fix: raise the nozzle temperature in 5 C steps, reduce part cooling, and keep")
        print("the room free of drafts.")
    else:
        print("\nNothing in this list matches. Check the slicer preview for missing geometry,")
        print("re-slice with a stock printer profile, and watch the first layer in person.")

if __name__ == "__main__":
    main()

Output Contract

When this skill is triggered, deliver:

• The recommended filament with a one-line reason, plus its starting nozzle and bed temperatures.
• The four slicer settings changed from the stock profile (layer height, wall count, infill, supports), with the actual numbers used.
• First-layer plan: bed prep, first-layer speed, and what a good first layer looks like.
• If the print failed: the symptom, the matched cause from the diagnostic table or script, and the fixes in the order to try them. One fix at a time, then reprint.

Operating Rules

1. Start from the slicer's stock profile for the user's printer. Do not stack guesses on a profile nobody has seen work.
2. Change one thing at a time when troubleshooting. Two changes at once teaches nothing and hides the real fix.
3. Treat temperatures as starting points, not gospel. Brand, color, and printer all move the numbers; a temperature tower settles arguments.
4. Do not recommend ABS to a beginner without an enclosure and a ventilation plan. Say so plainly.
5. Bed adhesion is a setup problem, not a glue problem. Clean plate and correct Z-offset come before adhesive sprays.
6. Never claim a command, menu path, or pricing detail from memory. Slicer UIs move between versions; give setting names, not click paths. Label prices and version-specific steps as "confirm before quoting" when they were not verified today.
7. Fire safety is not optional. Never tell someone to leave a printer running unattended, and never skip the enclosure/ventilation warning for ABS fumes.