Group Assignment — 3D Printing Design Rules

1) 3D Printing Technology

3D printing is a way to make real objects from a digital design by adding material layer by layer. It is also called additive manufacturing. It is useful for making prototypes, models, tools, and custom parts quickly.

Common 3D printing technologies

SLA: uses light to harden liquid resin.
SLS: uses a laser to fuse powder.
FDM: melts plastic filament layer by layer.
DLP, MJF, PolyJet, DMLS, EBM: other advanced methods.

At FabLab Hisar, we mainly use FDM-type printers for our 3D projects.

2) FDM Printers in the Lab

In FabLab Hisar, there are many FDM-type 3D printers for rapid prototyping (total: 19). Below are some machine types used in the lab.

Printer wall overview screenshot — Lab printer wall overview (screenshot).

Bambu Lab A1

FDM 256×256×256 mm Open frame

Build Volume: 256 × 256 × 256 mm
Max Speed: up to 500 mm/s
Max Hotend Temp: 300°C
Nozzle: 0.4 mm (optional: 0.2 / 0.6 / 0.8 mm)
Filament Diameter: 1.75 mm
Type: bed-slinger

Bambu Lab A1 screenshot — Bambu Lab A1 (screenshot).

Bambu Lab A1 Mini

FDM 180×180×180 mm Compact

Build Volume: 180 × 180 × 180 mm
Max Hotend Temp: 300°C
Nozzle: 0.4 mm (optional: 0.2 / 0.6 / 0.8 mm)
Filament Diameter: 1.75 mm
Type: compact open-frame printer

Bambu Lab A1 Mini screenshot — Bambu Lab A1 Mini (screenshot).

Bambu Lab X1

FDM (CoreXY) Enclosed Lidar

Build Volume: 256 × 256 × 256 mm
Max Speed: up to 500 mm/s
Max Hotend Temp: 300°C
Max Acceleration: up to 20 m/s² (20,000 mm/s²)
Enclosure: Yes
Features: lidar-assisted features, better compatibility with stronger materials

For this assignment, we focus on the Bambu Lab P1S.

Bambu Lab X1 / lab printer screenshot — Bambu Lab X1 (screenshot).

Bambu Lab P1S

FDM 256×256×256 mm Enclosed

Build Volume: 256 × 256 × 256 mm
Max Speed: up to 500 mm/s
Max Hotend Temp: 300°C
Enclosure: Yes
Typical Materials: PLA, PETG, TPU, ABS, ASA (depending on setup)

Short analysis: P1S is fast and enclosed, great for reliable prototyping and printing materials like ABS/ASA more consistently.

Photo of the printer wall — Photo of our printer wall.

3) How To Add Filaments To Machines In Our Lab

3a) Bambu Lab A1

Get the filament you will use.

Filament spool — Step 1: pick the filament.

Place the PLA filament on the holder and feed it into the tube.

On the screen: Filament → Load.

When loading finishes, filament should come out of the nozzle.

Filament coming out of nozzle — Load complete.

For unloading: Filament → Unload.

Follow the on-screen prompts and remove the filament when reminded.

Unloading progress screen — Unloading progress.

Remove filament reminder — Reminder to remove filament.

This is the basic workflow for loading/unloading on the Bambu Lab A1.

3b) Bambu Lab P1S

Similar to A1, but the screen interface and filament placement are different.

Insert filament from the back of the machine (top goes into the tube).

Feeding filament into P1S from the back — Filament enters from the back.

On the screen: Feeding → Load. Use the button/arrows to navigate.

Wait until the printer shows a message like: “Current filament is deploying.”

P1S deploying filament message — Deploying filament message.

Confirm filament is loaded by checking the nozzle for a small amount of filament extruding.

Filament extruding from nozzle — Filament extruding confirms load.

For unload: Feeding → Unload.

When the screen prompts you, pull the filament out of the tube.

3c) Bambu Lab A1 Mini

Get your filament and feed it into the tube.

Feeding filament on A1 Mini — Feeding filament into the tube.

On the screen: Filament → Load.

A1 Mini load screen 1 — Load screen (1).

A1 Mini load screen 2 — Load screen (2).

If needed, push filament further until you see new filament from the extruder.

A1 Mini prompt to push filament — Prompt to push filament.

For unloading: Filament → Unload.

A1 Mini unload done screen — Unload completed screen.

Pull the filament out and you should see a final confirmation screen.

3 Extra) Changing the Hotend Heater + Hotend (Bambu Lab A1 Mini)

1) Safety and Preparation

Unload filament first (wait for “unload completed”).
Turn the printer OFF and unplug it.
Wait until the nozzle/hotend is fully cool.

2) Open the hotend replacement cover

Open the front cover on the toolhead (hotend replacement cover). Use a small Allen key to loosen the screw, then pull the cover away carefully.

3) Remove the hotend heater

Pull the hotend heater down and out gently.

Removing hotend heater step 1 — Removing the hotend heater.

Removing hotend heater step 2 — Heater removed.

4) Change the hotend heater

Insert the new heater into the same place as the old one.

5–8) Reassemble

Reinstall screws and make sure parts are secured.
Insert the new hotend. Ensure it is parallel and there is no gap.
Put the cover back to finish.

Needle comparison 1 — Hotend/nozzle comparison (1).

Needle comparison 2 — Hotend/nozzle comparison (2).

4) 3D Printing Materials

FDM printing supports many materials, each with different strengths and limitations. Below is a quick cheat sheet of common filaments.

PLA: rigid, easy to print, good quality. Best for prototypes and decorative prints.
ABS: tough and impact resistant. Needs higher temps and can warp; enclosure helps.
PETG: strong and durable, easier than ABS, good chemical resistance.
Nylon: very strong and durable but absorbs moisture; usually needs enclosure/heated bed.
TPU: flexible and elastic; can be harder to print.

Note: We used only PLA during the design rule tests because ABS releases fumes which is not ideal in a lab environment.

Material	Advantages	Disadvantages	Typical Temps	Hardware
PLA	Cheap, easy, good surface quality	Brittle, degrades outdoors	Bed: 50–60°C Extruder: 190–220°C	Standard FDM printer
ABS	Impact resistant, durable, low cost	Warping, adhesion issues, fumes	Nozzle: 230–250°C Bed: 80–110°C	Heated enclosure recommended
PETG	Strong, durable, easier than ABS	Can have imperfect layer behavior	Nozzle: 230–250°C Bed: 70–80°C	Standard FDM printer
Nylon	Excellent mechanical properties, low friction	Absorbs moisture	Nozzle: 240–260°C Bed: 70–100°C	Often needs hardened nozzle / enclosure
TPU	Rubber-like flexibility	Harder to print, can be expensive	Nozzle: 210–230°C Bed: 20–60°C	Direct drive preferred

Exploring Bambu Studio (Bambu Slicer)

What is Bambu Studio?

Bambu Studio is slicing software that prepares a 3D model for printing. You import a model (.stl / .step), select printer + material + settings, and the slicer creates printable toolpaths (layers + movements).

It includes tools like G-code preview, multiple plates, remote control/monitoring, auto-arrange/orient, support generation, and per-object/per-part settings.

What we used it for

Import the 3D model
Select printer
Select filament/material + settings (layer height, supports, infill, speed, etc.)
Slice the model
Send to printer / export file
Monitor the print

Import model in Bambu Studio — Import model.

Select printer in Bambu Studio — Select printer.

Select filament and settings — Select filament + settings.

Slicing preview screenshot — Slice preview.

Send to printer screenshot — Send to printer / export.

Design Rules

Overhang / Angle Test

Overhangs extend outward with no material directly underneath. Many printers can handle up to about 45° without supports, but it depends on printer + material + cooling.

Overhang test print — Overhang test example.

Bridging Test

Bridging prints across an empty gap without supports. Shorter gaps are usually easier. We achieved a successful bridge using Bambu Studio settings.

Anisotropy

Because prints are layered, strength changes by direction: parts are usually weaker across layer lines. This matters for mechanical parts that carry force.

Surface Finish

Surface finish depends on layer height, printer resolution, material, and post-processing (like sanding). Our print was mostly clean, but a sphere had a small bulge which we removed with a flush cutter.

Clearance and Warping

Clearance is the gap between supports and the part (often ~0.2–0.5 mm depending on printer/material). Good clearance makes supports easier to remove.

Clearance example print — Clearance example.

In our clearance test, we saw slight warping on the bottom edge, likely from bed adhesion or temperature changes. Better first-layer calibration and adhesion would improve this.

Warping example on bottom edge — Warping observed on the print.

Supports

Supports are temporary structures for overhangs above ~45° and complex geometry. They improve success and quality but increase time and material usage. Good orientation and settings can reduce support needs.

Infill Patterns and Density

Infill is the internal structure of a print. Density ranges from 0% to 100%. Many prototypes work well at around 20%, while mechanical parts often need higher values (e.g., ~50%+).

Infill density setting screenshot — Infill density setting.

Infill pattern affects strength, flexibility, and print time. We printed these patterns at 20% density.

Printed infill patterns photo — Infill pattern comparison print.

Bambu Studio infill patterns list screenshot — Infill patterns list in Bambu Studio.

Pattern notes (20% density)

Cross Hatch: criss-cross lines; balanced and practical (fast–medium).
Lines: straight parallel lines; fastest for low-stress prints.
Grid: 2D squares; common general-purpose option (fast).
Triangles: 2D triangles; better strength than lines/grid (medium).
Tri-Hexagon: mix of triangles/hexagons; strong and efficient (medium).
Honeycomb: hexagons; strong but can be slower (medium–slow).
3D Honeycomb: more balanced internal support; slow.
Cubic: 3D pattern; balanced strength (medium).
Support Cubic: denser only where needed; efficient (medium–fast).
Optigram Spiral: continuous curved path; smooth flow (medium).
Archimedian Chorda: curved chord geometry; decorative + moderate support (medium).
Gyroid: smooth 3D waves; excellent strength/consistency balance (medium).
Concentric: follows outer shape; more aesthetic than strong (medium).
Aligned Rectilinear: consistent-direction rectilinear; predictable and fast.
Hilbert Curve: space-filling curve; interesting geometry (medium–slow).
Lightning: internal branches only where needed; very fast + low material.
Rectilinear: basic straight-line infill; fast general use.

Infill angle: Most slicers default to ~45° so both X and Y motors work efficiently. Changing infill direction can improve strength/flexibility, especially if the part’s walls are diagonal.