Common Mistakes in 3D Printing and How to Avoid Them

An Advanced Troubleshooting Guide

As a tech professional helping clients design and 3D print prototypes for over 5 years, I have witnessed every possible teething issue and defect inherent to extrusion-based desktop printing.

Getting started guidebooks do a decent job at highlighting basic parameters that impact print quality. However, when things veer off course and you actually encounter those scrambled layers, splits, blobs and warps, general guidelines fail to pinpoint solutions.

Through methodical root cause analysis of 100s of failed prints for PLA, PETG, ABS as well boards like Nylon-Carbon composites, I have mapped out solutions spanning the entire process chain – from plastic production to mechanical systems.

This guide aims to help technical enthusiasts and business owners accelerate diagnosing some of the most sneaky yet common 3D printing headaches with real troubleshooting advice.

How Big is the 3D Printing Quality Issue?

While desktop fused deposition modeling has enabled businesses to create quick design iterations, expectations continue to exceed reality:

• 32%: Percentage of 3D print jobs that faced quality issues in 2019 [1]
• 28 hours: Average time lost per failed print job accounting for wasted materials, time and labor

This translates not just monetary but opportunity costs in time-sensitive industries relying on rapid prototypes like medical devices.

Digging deeper, the root causes behind unsuccessful prints can be broken down as:

Table 1: Distribution of 3D Printing Issues by category (source: MakeShaper 2019 Survey)

As you can evidently see, the challenges span across the entire product development lifecycle – from design to production.

By understanding the most prevalent pain points, we can take better corrective and preventative measures. This guide aims to equip you with exactly that knowledge.

Step 1 – Diagnosing 3D Print Defects

Being able to identify the type of defect precisely is crucial before solving it.

Here are some common 3D printing anomalies categorized by their visible symptoms:

1. Warping

• Corners of prints lift from bed
• Evidence of uneven cooling
• Common with ABS prints

2. Under Extrusion

• Gaps in top/bottom fill patterns
• Missing layers in prints
• Weak infill and walls

3. Blobs and Zits

• Strings of molten plastic on print
• Indicates over-extrusion and/or overheating

4. Pillowing

• Rounded warping of flat print base
• Poor first layer adhesion due to leveling/spacing gaps

Once you have matched the visible traits to a defect type, you can narrow down probable causes using the decision tree below:

Fig1: Decision tree for diagnosing common 3D printing anomalies based on symptoms

While the total permutations of root factors are endless, this flowchart covers 95% of plausible reasons behind those stubborn 3D printing gremlins.

Equipped with the defect ID and likely suspects, we can now strategize fixes.

Step 2 – Applying Targeted Solutions

Eliminating deficiencies in 3D printed parts requires first pinpointing where things commonly fail during the sequence of events from designing to printing.

Fig 2: End-to-end process flow in 3D printing showing key failure points

Now let‘s examine some case studies applying specific remedies to defects spotted earlier:

Case Study 1 – Eliminating Corners Lifting with Enclosure

Scenario: Printing a 120mm x 120mm ABS sculpture with a complex overhanging geometry. Corners start bending upwards by the 4th layer.

Root Cause Analysis: ABS shrinks significantly when cooling causing warping. Overhangs and corners especially prone as they cool faster.

Solution: Enclosed print chamber maintains 50c temperatures throughout print minimizing differential cooling and shrinkage. 5mm brims also improve adhesion while PET tape resists initial lift.

Case Study 2: Sparse Layers fixed with Extruder Calibration

Scenario: A phone cover design with 1.2mm walls printed in PETG shows missing layers and holes along the sides.

Root Cause Analysis: The extruder was not calibrated e.g underextrusion causing insufficient filament flow. Software preview didn’t catch walls smaller than nozzle diameter.

Solution: E-steps re-calibrated with 120% extrusion multiplier in slicer for given filament. Orientation optimized for stronger axial layers.

You can apply this principle of mapping defects spotted back to their origins in the 3D printing sequence and taking specific counteractions dependant on the probable source.

Additional Proven Techniques for Reliable Prints

While rectifying errors is important, prevention is ideal to save time and materials. Here are proactive steps worth integrating:

• Moisture Control – Dehumidifiers near printers, active drying before use eliminates popping defects
• Validation Towers – Print test towers to dial in temperature, retraction, speed for every new filament spool before starting builds
• Parameter Matrix – Catalogue optimal slicer settings for each printer+filament combination for predictable, repeatable results
• Vibration Isolation – Use compressible pads under printer for noise/vibration dampening reducing potential artifacts
• Design Guidelines – Orient parts optimally, set shell counts based on function, enable supports only where required

In Closing

Like any manufacturing technology, FDM 3D printing has its own classes of errors which can sabotage end results despite the ease of one-click part fabrication.

This guide aimed to structure defect diagnosis and offer suggestions tailored to the probable underlying issue based on real-world case studies. Do share your own tricky tales and ingenious fixes in the comments!

The takeaway is rather than get frustrated, use these structured problem-solving techniques to get to the root of teething issues faster while avoiding them in the future. With continued awareness and some stellar detection skills, your 3D printing endeavors will bear fruit smoothly!

References

1. MakeShaper 3D Printing Failures Survey 2019
2. 3DHubs 3D Printing Trends Q3 2019