Week 05 — Group Assignment

3D Printing Design Rules

This group assignment focused on testing the design rules of the 3D printers available in our lab environment. The goal was to evaluate how different machines behave under the same test conditions, identify practical limits for common design features, and document the parameters that affect print quality, dimensional accuracy, and reliability.

1. Checklist

✅ Identified the 3D printers available in the lab and their main characteristics
✅ Tested design rules using calibration, tolerance, and dimensional verification models
✅ Compared FDM workflows using Bambu Lab X1E and Ultimaker S5 printers
✅ Recorded common printing settings such as layer height, temperature, speed, and infill
✅ Evaluated tolerances, bridge distance, overhang angle, and dimensional accuracy
✅ Documented observed failures such as vibration-related adhesion problems and stringing
✅ Included practical SLA considerations for Form 4 such as support strategy, inclination, hollowing, and drain holes
✅ Added screenshots, printed results, downloadable files, and process video

2. Lab Spaces

The tests and observations were developed considering the 3D printing resources available in two workspaces: StartLABS in Quito and the fabrication space used by our teammates at the University of Cuenca.

StartLABS 3D printing space — StartLABS fabrication space in Quito, where part of the 3D printing tests were developed.

University of Cuenca lab space — University of Cuenca fabrication lab used by teammates for additional testing and documentation.

3. Machines Used

Our lab setup includes FDM and SLA technologies. For the measured tests in this assignment, we used the Bambu Lab X1E and Ultimaker S5 printers under equivalent FDM conditions. We also documented key design considerations for the Form 4 resin workflow.

Machine	Technology	Main characteristics	Typical use
Bambu Lab X1E + AMS	FDM	High-speed printing, strong dimensional consistency, automated features, AMS multi-material support	Rapid prototyping, functional parts, dimensional tests, fast iteration
Ultimaker S5	FDM	Reliable industrial workflow, dual extrusion capability, stable large-format printing	Technical prototyping, robust parts, educational and professional production
Form 4 + Wash + Cure	SLA	Very high detail, smooth finish, requires wash and cure post-processing	High-detail parts, complex small geometries, aesthetic or precision-focused prints

4. Machine Comparison

Feature	Bambu Lab X1E	Ultimaker S5	Form 4
Technology	FDM	FDM	SLA
Nozzle / optical system	0.4 mm nozzle	0.4 mm nozzle	Resin light-based curing system
Resolution	Good	Good	Very high
Speed	Very high	Moderate	Moderate
Tolerance behavior	Excellent	Good	High accuracy, but strongly dependent on orientation and supports
Bridge test	Up to 36 mm	Up to 36 mm	Not evaluated in the same way
Overhang test	Up to 70° with visible filament at the limit	Up to 60° cleanly, filament visible at 70°	Requires support planning rather than unsupported overhang evaluation
Post-processing	Low	Low	High: wash and cure required

5. Common Materials

Material	Main advantage	Main limitation	Typical use
PLA	Easy to print, stable, low warping	Lower heat resistance	General prototyping and dimensional tests
PETG	Better toughness and chemical resistance	May produce more stringing	Functional parts and medium-duty prototypes
ABS	Stronger and more temperature resistant	Warping and enclosure sensitivity	Technical functional parts
TPU	Flexible	More difficult to control dimensionally	Soft or elastic components
Standard Resin	Excellent detail and smooth surface	Requires careful handling and post-processing	Detailed small models and visual prototypes
Tough / Engineering Resin	Better performance for functional resin parts	Still requires supports, wash, and cure	Engineering validation and precision applications

6. Printing Parameters Used for FDM Tests

Material: PLA
Nozzle diameter: 0.4 mm
Layer height: 0.2 mm
Printing temperature: 210 °C
Infill: 15%
Infill pattern: Triangular
Printing speed: 70

The same general parameters were used to maintain a fair comparison between Bambu Lab X1E and Ultimaker S5. This allowed us to focus the analysis on machine behavior, dimensional response, and print quality under similar operating conditions.

7. Test Files

Three reference files were used during the evaluation process: a complete calibration test, a tolerance test, and an XYZ calibration cube. The first setup was prepared in Bambu Studio and later the STL files were reused in Cura for the Ultimaker tests.

Download calibra.3mf Download toleran.stl Download cube.3mf

8. Bambu Lab X1E — Digital Preparation

The first set of tests was prepared in Bambu Studio. These screenshots correspond to the calibration test, tolerance test, and XYZ calibration cube before printing.

Bambu Studio calibration test — test1 — Full calibration test prepared in Bambu Studio.

Bambu Studio tolerance test — test2 — Tolerance test prepared in Bambu Studio.

Bambu Studio XYZ calibration cube — test3 — XYZ calibration cube prepared in Bambu Studio.

9. Bambu Lab X1E — Printed Results

Printed calibration test on Bambu Lab X1E — test4 — Printed full calibration test on the Bambu Lab X1E. Most features printed correctly.

Printed tolerance test on Bambu Lab X1E — test5 — Printed tolerance test on the Bambu Lab X1E. The result was very good and clearly readable.

Printed XYZ cube on Bambu Lab X1E — test6 — Printed XYZ calibration cube on the Bambu Lab X1E.

XYZ cube measured with caliper — test7 — The 25 mm XYZ calibration cube measured 24.92 mm on the Bambu Lab X1E, showing a dimensional deviation of -0.08 mm.

A failure was observed in one of the unsupported features of the calibration test. Due to movement and vibration, that area did not adhere correctly during the print, which caused the feature to fail while the rest of the part printed successfully.

10. Printing Process Video

The following timelapse video shows the Bambu Lab X1E printing the complete calibration model.

11. Ultimaker S5 — Digital Preparation in Cura

The same calibration model was later imported into Cura to compare the print behavior in the Ultimaker S5 using two wall thickness configurations: 0.8 mm and 1.2 mm.

Cura setup for 0.8 mm wall thickness — test8 — Cura preparation with 0.8 mm wall thickness.

Cura setup for 1.2 mm wall thickness — test10 — Cura preparation with 1.2 mm wall thickness.

12. Ultimaker S5 — Printed Results

Ultimaker printed test with 0.8 wall — test11 — Printed calibration test with 0.8 mm wall thickness.

Ultimaker printed test with 1.2 wall — test12 — Printed calibration test with 1.2 mm wall thickness.

All printed test parts together — test13 — Combined view of the printed tests for direct visual comparison.

In the Ultimaker prints, fine hair-like strings were visible between some features. This was related to retraction settings not being activated between separate printed sections, which led to stringing artifacts.

13. Measured Design Rules

13.1 Tolerance Test

0.1 mm clearance: too tight
0.2 mm clearance: optimal fit
0.3 mm clearance: looser fit

13.2 Bridge Test

Bambu Lab X1E: printed successfully up to 36 mm without support
Bambu Lab X1E: at 40 mm the lower filaments began to sag slightly
Ultimaker S5: printed successfully up to 36 mm without support
Ultimaker S5: at 40 mm the lower filaments also began to sag

13.3 Overhang Test

Bambu Lab X1E: good performance up to 70°, although at the limit the filament became visible and less clean
Ultimaker S5: reliable performance up to 60°
Ultimaker S5: at 70° the filament became visibly exposed and quality decreased

13.4 Dimensional Accuracy

Designed cube: 25 mm × 25 mm × 25 mm
Measured cube on Bambu Lab X1E: 24.92 mm
Deviation: -0.08 mm

14. Important 3D Printing Rules

The following table summarizes the most important design and process rules considered during the group analysis. These same criteria are useful when preparing both FDM and SLA prints.

Rule / Parameter	Why it matters	Typical consideration
Supports	Prevent collapse in overhangs and unsupported regions	Use only when necessary and optimize for easy removal
Model orientation	Affects surface finish, strength, support amount, and print time	Rotate the model to reduce unsupported geometry
Layer height	Defines detail level and print time	0.2 mm is balanced for FDM; lower values improve detail
Infill percentage	Defines rigidity, weight, and material use	15% is efficient for general test models
Printing temperature	Controls flow and adhesion	Must match the selected material profile
Print speed	Higher speed reduces time but can affect quality	Use moderate speed when evaluating accuracy
Tolerances	Important for assemblies and moving parts	Leave enough clearance; in our test 0.2 mm worked best
Warping	Can lift or deform the part from the base	Use good bed adhesion and stable environmental conditions
Bed adhesion	Critical for print stability	Incorrect adhesion can cause early print failure
Retraction	Reduces stringing between separate printed regions	Important when the part contains multiple separated features
Wall thickness	Affects structural rigidity and consistency	Tested here with 0.8 mm and 1.2 mm walls in Ultimaker

15. SLA Design Considerations — Form 4

Although we did not run the same measured comparison tests on the Form 4 during this group assignment, we documented several important design rules that are specific to resin printing and are essential for reliable results.

Inclined orientation: resin parts are commonly printed at an angle to improve surface quality, reduce suction effects, and improve resin flow.
Supports and bases: supports must be placed strategically, and the base structure must stabilize the part during the print.
Hollow models: large resin parts are often hollowed to reduce material use and print time.
Drain holes: hollow parts require small holes so trapped resin and internal pressure do not remain inside the model.
Internal vacuum effect: without proper venting, enclosed volumes can create suction or pressure issues that affect print reliability.
Post-processing: resin parts must be washed and cured after printing to reach their final state.

16. Analysis

Under the same general PLA settings, the Bambu Lab X1E and Ultimaker S5 both produced very good results in bridge performance, reaching 36 mm before visible sagging appeared at 40 mm. The tolerance test clearly showed that 0.2 mm is the most reliable clearance value for fit-based assemblies in our conditions.

The Bambu Lab X1E achieved a good dimensional response in the XYZ calibration cube, measuring 24.92 mm for a nominal 25 mm cube. This small deviation indicates good dimensional consistency for practical prototyping. The Bambu calibration model also showed that isolated unsupported details can fail if local adhesion is lost due to movement or vibration during the process.

In the Ultimaker prints, the main visible defect was stringing. This did not come from a major geometry failure, but rather from retraction not being enabled correctly between separated features. This is a good reminder that machine capability and slicer settings must be evaluated together.

17. Conclusions

The tolerance test showed that 0.2 mm is the most reliable clearance for fit-based FDM printed parts under our selected conditions.
Both the Bambu Lab X1E and the Ultimaker S5 were able to bridge up to 36 mm without support, while 40 mm began to show filament sagging.
The Bambu Lab X1E achieved a good overhang result up to 70°, although the filament became visible at the limit of the test.
The Ultimaker S5 produced stable results up to 60°, with visible quality reduction when reaching 70°.
The measured XYZ cube printed on the Bambu Lab X1E showed a small dimensional deviation of -0.08 mm, which is acceptable for prototyping applications.
One of the main observed print failures was caused by insufficient adhesion in a moving unsupported region, demonstrating how vibration and local instability affect the result.
Stringing in the Ultimaker tests showed that slicer settings such as retraction are as important as the mechanical quality of the printer.
For SLA workflows such as the Form 4, orientation, support placement, hollowing, and drain holes are essential design decisions and must be considered from the start of the modeling process.