Britforge3D

As projects grow, parts must fit together reliably. Designing for assembly is where many 3D prints fail.

Snap Fits in 3D Printing

Snap fits rely on controlled flex.

Best practices:

• Use PETG or nylon (not PLA)
• Avoid sharp internal corners
• Design generous lead-in angles
• Test multiple tolerances

Printed snap fits should flex once not repeatedly.

Press Fits and Interference

Press fits require extremely careful tolerancing.

Guidelines:

• Start with 0.1–0.2 mm interference
• Test with small calibration prints
• Account for material shrinkage

Never assume theoretical dimensions will work first time.

Modular Design Benefits

Breaking designs into modules allows:

• Easier printing
• Better orientation
• Reduced support
• Improved repairability

Fastening options include:

• Screws with heat-set inserts
• Pins and dowels
• Adhesives (epoxy, CA glue)

Tolerance Stacking

Multiple small inaccuracies add up.

Avoid:

• Long chains of mating parts
• Tight tolerances across many components
• Single-point failure designs

Instead, design adjustment points.

Professional Assembly Support

BritForge3D regularly prints:

• Multi-part assemblies
• Mechanical enclosures
• Functional prototypes

We can advise on fit, tolerance, and assembly strategy before printing.

Upload your project at BritForge 3D

Understanding 3D Printing File Types: STL, 3MF, OBJ and G-code Explained

When a customer uploads a file for 3D printing, the first question we consider is not how large the part is or what material it requires. The first question is much simpler: what file format are we working with?

File type plays a significant role in print reliability, geometry accuracy, material settings, and even colour information. Many users treat file formats as interchangeable, but they are not. Each format exists for a reason, and choosing the correct one can improve workflow efficiency and reduce print errors.

In this lesson, we will explore the four most common file types used in 3D printing: STL, 3MF, OBJ, and G-code. More importantly, we will examine when to use each one and why.

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Why File Format Matters in 3D Printing

A 3D printer does not understand design software files such as SolidWorks, Fusion, or Blender files directly. Instead, those designs must be exported into a format that slicing software can interpret.

The file you export determines:

• How geometry is stored
• Whether units are preserved
• Whether colour and material data are included
• Whether slicing settings travel with the model
• How easily the file can be repaired

Using the wrong format can introduce scaling issues, lost metadata, corrupted geometry, or unnecessary workflow steps.

Understanding file formats allows you to control your process rather than react to problems later.

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STL – The Industry Standard

The STL file (Standard Tessellation Language or StereoLithography) is the oldest and most widely recognised format in 3D printing.

STL files describe geometry using triangles. Every curved surface is approximated by a mesh of small triangular faces. The smaller and more numerous the triangles, the smoother the surface appears.

However, STL files contain only geometry. They do not store:

• Units (mm or inches)
• Colour
• Material data
• Print settings

This simplicity is both a strength and a limitation.

Benefits of STL

STL is universally supported. Nearly every slicer, CAD package, and 3D printer workflow accepts STL files. Because the format is simple, files are generally stable and predictable.

For single-material functional parts, STL is often perfectly adequate.

Limitations of STL

Because STL does not store units, scale errors are common. A part designed in millimetres may open as inches in another system.

STL also cannot store multiple bodies intelligently, colour data, or advanced metadata.

For simple prints, STL works well. For more complex workflows, it begins to show its age.

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3MF – The Modern Alternative

3MF (3D Manufacturing Format) was developed to solve the limitations of STL.

Unlike STL, 3MF files store:

• Units
• Multiple bodies
• Colour information
• Material assignments
• Print settings (when exported from slicers)

This makes 3MF far more powerful for modern workflows.

Why 3MF Is Often Better for 3D Printing

Because 3MF preserves units, scaling errors are eliminated. What you design is what opens in the slicer.

3MF also allows multi-material and multi-colour information to travel with the file. If you are using a multi-material printer, this is critical.

Additionally, some slicers store support placement and slicing profiles inside the 3MF file. This makes collaboration easier because another user can open the file exactly as intended.

When to Choose 3MF

If you are working in a modern slicer and want to preserve configuration, or if you are printing multi-material parts, 3MF is usually the better choice.

For professional workflows, 3MF is increasingly becoming the preferred format.

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OBJ – Geometry with Visual Data

OBJ files are commonly used in animation and 3D modelling rather than manufacturing, but they also have applications in 3D printing.

Like STL, OBJ files describe geometry through mesh data. However, OBJ files can also store:

• Colour data
• Texture references
• Surface information

This makes OBJ useful for full-colour printing systems.

When OBJ Makes Sense

If you are printing artistic models, figurines, or textured parts that require colour mapping, OBJ can be valuable.

However, OBJ files can be larger and more complex than STL. They may also include unnecessary data for simple functional prints.

For most engineering parts, OBJ is not required.

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G-code – The Machine Instruction File

G-code is very different from STL, 3MF, or OBJ.

While those formats describe geometry, G-code describes movement instructions for the printer.

Once a file is sliced, the slicer converts the model into G-code. This file contains:

• Exact nozzle movements
• Extrusion rates
• Temperature commands
• Fan speeds
• Layer heights

G-code is printer-specific. It is generated for a particular machine, with specific settings.

Why You Don’t Share G-code as a Design File

Because G-code contains machine instructions, it is not portable in the same way geometry files are.

A G-code file created for one printer may not work correctly on another due to:

• Different bed sizes
• Firmware differences
• Extruder configurations
• Temperature limits

For this reason, when sending a file to a professional 3D printing service, you should always send geometry files (STL or 3MF), not G-code.

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Choosing the Right File Type

So how do you decide?

If you are printing a simple single-material part and need universal compatibility, STL is safe and reliable.

If you want to preserve units, materials, and advanced data, 3MF is the superior modern option.

If you are working with colour textures or artistic models, OBJ may be appropriate.

If you are printing directly from your own slicer to your own machine, G-code is the final production file — but not something to share externally.

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Professional Workflow Recommendation

At BritForge3D, we recommend:

• 3MF for most modern workflows
• STL for compatibility and simple parts
• Avoid sending G-code unless specifically requested

We re-slice all files to ensure compatibility with calibrated machines and optimised material profiles.

Sending geometry files instead of machine code allows us to ensure print strength, dimensional accuracy, and material suitability.

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Common Mistakes to Avoid

One of the most common mistakes is exporting STL with extremely low mesh resolution. This results in visible flat facets on curved surfaces.

Another mistake is forgetting to check units before export.

Finally, some users send G-code assuming it guarantees identical results. In reality, it can introduce compatibility risks.

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Final Thoughts

Understanding file formats is not just about software preference. It is about workflow control.

Choosing the correct file format improves reliability, reduces errors, and supports better collaboration between designers and print services.

As 3D printing evolves, 3MF is increasingly replacing STL for professional workflows. However, STL remains deeply embedded in the ecosystem.

In the next guide, we will explore how to prepare files properly before upload — including mesh repair, manifold checks, and design validation.

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Why Doesn’t My 3D Scanner Capture Detail as Small as 0.02 mm?

One of the most common questions people ask after purchasing or using a 3D scanner is why the scanner does not capture detail as precisely as the specification suggests. Many scanners advertise resolutions such as 0.02 mm, yet when scanning real-world objects the captured model appears far less detailed.

This can be confusing and sometimes disappointing, especially for users expecting extremely fine detail. However, the answer usually lies not in the scanner being faulty, but in how scanner specifications, resolution, accuracy, and real-world conditions actually work.

Understanding these factors helps you get the best results from your scanner and avoid unrealistic expectations.

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Resolution vs Accuracy – The First Source of Confusion

When a scanner advertises a resolution of 0.02 mm, this does not mean it can reliably measure every feature at that size.

In most scanners, resolution refers to the smallest point spacing the scanner can record, not the true measurement accuracy.

These are two very different things.

Resolution describes the density of points in the captured mesh.
Accuracy describes how close those points are to the true dimensions of the object.

For example, a scanner may generate points every 0.02 mm, but the true dimensional accuracy may only be ±0.05 mm or ±0.1 mm depending on the scanning conditions.

This distinction explains why extremely fine features may not appear clearly even though the specification seems capable of capturing them.

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Surface Properties of the Object

Another major factor affecting scan detail is the surface of the object being scanned.

3D scanners rely on reflected light or structured light patterns to detect geometry. Certain surface types interfere with this process.

Highly reflective surfaces can scatter the projected light pattern, making it difficult for the scanner to calculate depth accurately. Similarly, very dark or matte surfaces may absorb too much light, reducing contrast.

Transparent or glossy materials are particularly challenging because the scanner may detect reflections rather than the actual surface.

This is why professional scanning workflows often use temporary scanning sprays to create a uniform matte surface that improves data capture.

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Distance from the Scanner

3D scanners operate within an optimal working distance. If the object is too close or too far away, the scanner cannot resolve small details properly.

Most scanners have a focus range or optimal capture distance, and fine detail is only captured when the object sits within this range.

If the scanner is held too far away, point density decreases and small features are lost. If it is too close, the scanner may struggle to maintain tracking or capture complete geometry.

Maintaining a consistent scanning distance is therefore critical for achieving the best resolution.

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Movement and Tracking Stability

Handheld scanners rely on stable tracking of the object’s surface while scanning. If tracking is lost or unstable, the software may smooth or average data during reconstruction.

This smoothing can remove small details that technically fall within the scanner’s resolution.

Even small hand movements or vibrations can affect point alignment. Professional scanning often uses tripods, turntables, or fixed scanning rigs to minimise movement and maximise accuracy.

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Lighting Conditions

Ambient lighting also influences scan quality.

Strong sunlight or bright studio lighting can interfere with structured light patterns used by many scanners. Excessive ambient light reduces contrast between projected patterns and the object’s surface.

Most scanners perform best in controlled indoor lighting where the projected pattern remains clearly visible to the sensors.

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Mesh Processing and Software Filtering

After scanning, software converts raw point cloud data into a mesh. During this process the software may apply smoothing, noise reduction, and hole filling.

These algorithms are designed to produce clean models but can unintentionally remove small features.

Many scanning applications include adjustable settings for mesh smoothing or detail preservation. Lower smoothing levels often retain more fine geometry.

Understanding these processing settings can significantly improve the final result.

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Object Size vs Feature Size

Resolution specifications are also influenced by the overall size of the object being scanned.

Scanning a large object spreads the available point density across a wider area. This means fewer points represent small features.

In contrast, scanning a smaller object concentrates point density and improves feature capture.

For this reason, some scanners perform better when scanning smaller sections individually rather than attempting to capture a large object in one pass.

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Calibration and Scanner Setup

Just like 3D printers, scanners require proper calibration.

Calibration ensures that cameras, sensors, and projection systems align correctly. If calibration drifts over time, accuracy can decrease.

Manufacturers typically provide calibration boards or routines. Running these periodically helps maintain optimal scanning performance.

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Understanding Real-World Scanner Performance

In practice, the advertised resolution of a scanner represents the best-case scenario under ideal conditions.

Real-world scanning involves variables such as lighting, object surface properties, movement, and software processing. Each of these factors can reduce the amount of detail captured.

This does not mean the scanner is performing poorly. It simply reflects the difference between laboratory specifications and practical operation.

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Improving Your Scan Results

While scanners cannot always achieve their theoretical limits, several techniques can significantly improve results.

Using matte scanning spray, maintaining the correct distance, scanning in stable lighting conditions, and adjusting mesh processing settings can all enhance detail capture.

Additionally, scanning smaller sections and combining them later often yields better results than scanning a large object all at once.

These practical adjustments often make the difference between an average scan and a highly detailed one.

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Final Thoughts

The advertised resolution of a 3D scanner represents the maximum point density it can achieve under ideal conditions, not the guaranteed detail level in every scan.

Factors such as surface reflectivity, lighting, distance, motion, calibration, and software processing all influence the final result.

Once you understand these variables, scanning becomes far more predictable and far less frustrating.

With the right setup and expectations, modern 3D scanners are capable of producing highly detailed and accurate models suitable for reverse engineering, product design, and digital archiving.

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Next Technical Guide

In the next guide, we will explore how to prepare scanned models for 3D printing, including mesh repair, hole filling, and converting scan data into usable CAD geometry.

Before uploading your design for 3D printing, it’s crucial to ensure your STL file is clean, watertight, and printable. Here’s a simple step-by-step guide to help you prepare your file for the best results.

1. Export Your Model to STL Format

Most CAD software can export to STL. Ensure you choose the right resolution — too low and your model looks blocky; too high and the file may be too large.

2. Check for Common Errors

• Non-manifold edges
• Holes or flipped normals
• Unwanted internal faces

3. Repair Your File

Use tools like Netfabb, Meshmixer, or Microsoft 3D Builder to automatically fix file errors before submitting.

4. Scale and Orient

Make sure the size matches your desired output and the orientation is optimal for your print goal.

5. Upload with Confidence

Once your file is ready, head to BritForge3D.co.uk and upload your STL to get an instant quote and professional results.

A Simple Guide

Before you print, you need the right file format. Not all 3D design files are created equal and some work better than others for printing.

Most Common 3D Printable File Types

• STL – The most universal format for 3D printing. Widely supported and ideal for simple shapes.
• OBJ – Includes color and texture data. Best for artistic models or miniatures.
• 3MF – A modern format with more metadata and better slicing support.

When to Use Each File Type

If you’re designing in Fusion 360, Tinkercad, or Blender, export as STL unless your project requires materials or textures.

Need help converting a file? We’re happy to assist before printing!