3D Printing Guide
How to Smooth 3D Prints: Complete Guide
Scott Gabdullin
Co-Founder & CEO
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3D printing has revolutionized the manufacturing industry, providing an affordable and accessible way to produce complex shapes and designs. However, sometimes 3D printed parts can have a rough surface finish, detracting from the overall appearance. This article will cover the different methods and techniques you can use to smooth 3D prints and achieve a professional-looking finish.
Table of Contents
Reasons for Rough Printing
It is common for 3D prints to come out rough, even for advanced users. Some 3D printing applications do not require a high surface finish, and irregular or porous surfaces may be acceptable. However, it is essential to take the necessary steps for smoothing 3D prints for applications requiring a high degree of precision and surface finish.
Many factors can contribute to rough surfaces, including the following.
- Layer Height: The layer height is the thickness of each layer of material deposited by the 3D printer. If the layer height is too high, the layers may not bond together correctly, leaving rough or porous surfaces.
- Extruder Temperature: If the extruder’s temperature is too low, the material may not melt completely, leading to rough or porous surfaces.
- Bed Adhesion: Poor bed adhesion can cause the layers to shift or lift during printing, resulting in rough or porous surfaces.
- Nozzle Diameter: The nozzle’s diameter affects the material’s flow rate and the consistency of the layer thickness. The too-small nozzle can cause clogging or jams, leading to rough or porous surfaces.
- Printing Speed: Printing can cause the layers to cool too quickly, leading to a rough surface finish.
- Material Properties: Certain materials, such as ABS, are prone to warping, which can cause rough or porous surfaces.
- Lack of Support Structures: Without proper support structures, overhanging or complex parts of the print can sag or collapse, leading to rough or porous surfaces.
3D printers that produce rough or porous surfaces can benefit from proper calibration and maintenance, as well as careful attention to printing parameters such as layer height, extruder temperature, bed adhesion, nozzle diameter, printing speed, and material properties.
Smoothing for a Better Final Product
Whether using your 3D print for prototyping, product development, or simply as a decorative piece, taking the time to smooth its surface can significantly improve the final result.
Smoothing the surface of a 3D print can significantly enhance its overall quality and make it look more professional. A smooth surface finish is visually appealing and gives the print a polished appearance.
It also has practical benefits, as rough or porous surfaces can negatively impact the print’s strength, durability, and overall functionality. In applications where precision is essential, a smooth surface allows for better fitting and tighter tolerances, making it more reliable.
Furthermore, a smooth surface provides a better feeling for paint or other coatings to adhere to, which can be important for applications where color or finish is essential.
Removing Excess Material
Removing excess material is a crucial step in the 3D printing process. It involves cutting away any support structures or extra material used during the printing process to achieve the final desired shape of the 3D print.
The method used to remove excess material will depend on the material used for the print, as well as the size and complexity of the object.
Let’s review some methods to remove excess material and smooth your 3D print project.
Heat Gun Smoothing
This technique involves using a heat gun to apply gentle heat to the surface of the 3D print. The heat causes the plastic to soften and flow, which can smooth out surface imperfections.
This method is most commonly used with ABS (Acrylonitrile Butadiene Styrene) filament, as it is a thermoplastic that can be reshaped with heat. However, it’s essential to use a low heat setting and move the heat gun slowly to avoid melting or distorting the print.
Pros
- Simple and affordable
- Removes warping, curling, and surface defects
- Used on a variety of materials
Cons
- Causes the material to soften or melt, altering its original shape
- Creates new surface defects if not used carefully
Solvents
Chemical smoothing, also known as solvent smoothing, is used to achieve a smooth and polished surface on 3D prints. This method involves immersing the 3D print in a chemical solution, such as acetone or ethyl alcohol, which dissolves the surface layer of the plastic and smoothes out rough or porous areas. The solvent evaporates over time, leaving behind a smooth and polished surface.
You can use chemical smoothing in conjunction with other methods, such as sanding or polishing, for optimal results.
However, it is crucial to follow the manufacturer’s safety guidelines when using chemicals and solvents and to handle the 3D print carefully, as the surface may become brittle and prone to cracking after chemical smoothing.
Pros
- Effective in smoothing out rough surfaces and reducing porosity
- Used on a variety of materials
- Simple and affordable
Cons
- Messy and time-consuming to clean up
- Weakens or damages the material if not used carefully
- Releases harmful fumes
Epoxy Resin
Epoxy resin smoothing is a technique that uses a layer of epoxy resin to achieve a smooth, glossy finish on a 3D print. This method can be applied to any type of filament, including ABS, PLA, and resin-based prints, making it a versatile option for surface smoothing.
The resin is applied to the surface of the 3D print, filling in any gaps and creating a smooth, glossy finish.
Pros
- Fills in gaps, creating a smooth, glossy finish
- Adds strength and rigidity to the 3D print
- Used on a variety of materials
Cons
- Messy and time-consuming process
- Challenging to achieve a consistent, even layer of resin without bubbles or drips
- Fumes are harmful if inhaled
- Yellows over time, affecting the appearance of the print
Priming
Priming involves applying a primer or filler to the surface of the 3D print to fill in any gaps or imperfections. The primer can then be sanded or polished to achieve a smooth surface.
This method is suitable for any filament and is especially useful for prints made with brittle or porous materials.
Pros
- Improves adhesion of subsequent coats of paint or resin
- Helps to achieve a smoother and more even finish
- Used on a variety of materials
Cons
- Adds an extra step to the smoothing process
- Messy and time-consuming to apply
Sanding
Sanding is a straightforward method for smoothing 3D prints. Sanding removes any rough or uneven areas on the surface of the 3D print.
Start using a low grit sandpaper, such as 120-grit, and work your way up to a higher grit, such as 800-grit. The key to successful sanding is to work slowly and evenly, covering all areas of the print.
Sand in a circular motion, and use a sanding block to apply even pressure. After sanding, you can use a soft cloth to remove dust or debris from the surface.
Pros
- Simple and affordable
- Effective in removing surface defects and smoothing rough surfaces
- Used on a variety of materials
Cons
- Time-consuming, especially if the surface is particularly rough
- Creates new surface defects if not used carefully
- Generates harmful dust if inhaled
Utility Knife
You can use a utility knife or box cutter to shave or scrape off any rough spots on the surface of the 3D print. This method is helpful for removing slight imperfections or trimming away any extra material.
Pros
- Simple and affordable
- Effective in removing minor imperfections and trimming away extra material
Cons
- Limited to smoothing smaller surface areas
- Creates new surface defects if not used carefully
Rotary Multitool
A rotary multitool, such as a Dremel, is a versatile tool that you can use for sanding, polishing, and cutting. It can be fitted with various attachments, such as sanding discs or polishing pads, making it a valuable tool for smoothing 3D prints. The tool’s variable speed setting allows for precise control, and its compact size makes it easy to use in tight spaces.
Pros
- Versatile tool that you can use for sanding, polishing, and cutting
- Variable speed setting allows for precise control
- Compact size makes it easy to use in tight spaces
Cons
- Creates new surface defects if not used carefully
- Time-consuming, especially if the surface is rough
- Generates dust that is harmful if inhaled
Smoothing Method Considerations
When deciding how to smooth 3D prints, it’s important to consider a number of key factors to ensure you get the best results.
Type of Material
Different 3D printing materials have different properties and will respond differently to other smoothing methods. It is crucial to consider the filament’s properties and choose a smoothing technique that will not negatively impact its strength, durability, or overall quality.
Desired Outcome
The final finish you want to achieve will also influence your choice of smoothing method. For example, epoxy resin smoothing may be the best choice if you want a glossy finish. On the other hand, sanding or vapor smoothing might be more appropriate if you are looking for a matte finish.
Level of Expertise
Different smoothing methods will require different levels of skill and experience. Some methods, like sanding and polishing, are relatively straightforward and can be performed by anyone with a basic level of experience. In contrast, others, like vapor smoothing or epoxy resin smoothing, may require more specialized knowledge and equipment.
Time
Some smoothing methods can be time-consuming, especially if you are smoothing a large or complex 3D print. If you work to a tight deadline, choose a quicker smoothing method, such as using a heat gun or solvent.
Equipment
Some smoothing methods require specialized equipment, like a heat gun, vapor chamber, or rotary multitool. Ensure you have access to the necessary equipment before choosing a smoothing technique.
Safety
Some smoothing methods, like solvents, can be hazardous if not handled properly. Ensure you know the safety considerations and follow the manufacturer’s instructions when using chemical or hazardous materials.
By carefully weighing these factors, you can select the best smoothing method for your 3D print and achieve the level of quality and finish you’re looking for.
Smoothing Recommendations and Considerations
When selecting a smoothing option, let’s look at some recommendations based on the material and how they respond to different smoothing options.
ABS
ABS (Acrylonitrile Butadiene Styrene) filament is a popular material for 3D printing due to its strength, flexibility, and affordability. However, ABS tends to produce rough and porous surfaces, which can impact the overall appearance and functionality of a 3D print.
Smoothing ABS using solvents, such as acetone, is a relatively straightforward process that can produce smooth and glossy results.
This method involves immersing the 3D print in acetone for a specified time and then removing it to allow the solvent to evaporate. The acetone dissolves the ABS and smooths the surface as it evaporates.
PLA
Smoothing PLA (Polylactic Acid) filament can be more challenging than ABS, but the results are worth it. Unlike ABS, PLA does not become brittle after filing, making it a more durable option for objects that will experience frequent handling.
Sanding and polishing are the most common methods for smoothing PLA filaments, and they can be effective in removing rough or porous areas. It is vital to choose the right grit sandpaper or polishing compound to achieve the desired level of smoothness.
Some users also employ heat-based smoothing techniques, which you should do as they can deform or soften the material. When smoothing PLA, it is also essential to consider the environment in which the 3D print will be used, as this can affect its durability and longevity.
Nylon
Nylon filament is known for its strength and flexibility, making it a popular choice for functional and load-bearing 3D prints. However, achieving a smooth surface with nylon can be challenging due to its rough texture.
Sanding and polishing are two methods you can use to improve the surface of nylon 3D prints, but it’s important to note that heat-based smoothing techniques may not be suitable for nylon. This is because nylon has a high melting point, so exposing it to high temperatures can cause it to degrade and weaken.
When working with nylon filament, it’s essential to be mindful of the smoothing technique used and to ensure that it is suitable for the material’s properties.
PETG
PETG (Polyethylene Terephthalate Glycol) filament is a popular choice for 3D printing because it has good durability and flexibility, making it well-suited for various applications.
Regarding smoothing behavior, PETG is similar to ABS and is relatively easy to smooth using solvents. This is because the plastic used in PETG filament is soluble in common solvents like acetone, which can dissolve the surface layer of the plastic and smooth out rough or porous areas.
Resin
Resin-based filaments are a 3D printing material known for producing highly detailed and smooth objects. However, they are also more delicate and require a different approach to smoothing.
Sanding and polishing are effective methods for smoothing resin-based prints, as they remove any rough or porous areas on the surface. However, heat-based smoothing techniques, such as using a heat gun, should be avoided with resin-based filaments.
This is because the heat can cause the resin to degrade, resulting in a loss of detail and an overall decrease in the quality of the 3D print. Additionally, it is important to handle resin-based prints carefully, as they can be more brittle and prone to cracking compared to other types of filaments.
Smoothing 3D Printed Objects
Achieving a smooth surface on 3D prints is important in producing professional-quality results. There are several smoothing techniques to choose from, including sanding, polishing, chemical smoothing, and using tools such as heat guns and rotary multitools. Each method has its advantages and disadvantages, so it’s essential to carefully consider your specific project needs and goals before choosing a smoothing technique.
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Scott Gabdullin
In 2021, Paul convinced Scott to partner up and launch a new online project built around their shared interest in 3D printing, 3DGearZone.
Scott brings 12 years of digital marketing experience and a hardcore work ethic to his new passion for 3D printing. If he is not working on this business, he is likely travelling and Overlanding across North America with his wife and 2-year-old son in their Jeep Rubicon.
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