Choose the best finishing method for your 3D prints
Today’s FDM 3D printers achieve excellent surface finishes despite producing items using layers. But why settle for a good surface finish when you can have a perfect surface finish? Join us to explore the best 3D printing surface finishing techniques available to you, from simple sanding to acetone vapor baths.
How to sand your 3D prints
Sanding your 3D prints is the easiest way to create beautiful surface finishes. That doesn’t mean the process is quick, and you need to be patient to get the best results with this method. You have two choices: hand sanding or electric sanding. Each option has its own benefits, so let’s take a look at them both to get you started.
Sanding 3D prints gives them a smooth finish. You can polish your sanded prints to give them a glossy finish or leave them unpolished for a matte effect.
How to Hand Sand 3D Prints
Although it can be time consuming, hand sanding is an effective way to finish your 3D prints and make them look great. Sandpaper can be found at hardware stores, online, and even in your old toolbox, but you should have sandpaper in different grits for the best results. Sanding blocks can also be used for this.
- Start with 150 to 220 grit sandpaper for the first round of sanding. This can be done dry as long as you don’t let heat build up that would melt the printed object.
- Follow this using 320 grit sandpaper for the next coat. Using a small amount of water at this point will help keep the object cool while you work on it.
- Finally, finish the sanding process with 600 grit sandpaper. It’s a good idea to use water at this point to ensure the print doesn’t melt.
- You can follow the 600 grit sandpaper with even finer sandpaper if desired, but the surface will be very smooth and free of coat lines at this point.
Rubbing the sandpaper or sanding block in circular motions is a good way to avoid scratches or an uneven finish. Apply little pressure when sanding 3D printed plastics; the sandpaper should do all the work for you.
How to Power Sand 3D Prints
Using a power tool to sand your 3D prints is quick and efficient, and you can choose from a range of tools to get the job done. Belt sanders, orbital sanders, and detail sanders are the most common electric sanders available on the market. Any type of electric sander will work, although detail sanders are generally considered the best for 3D print finishing.
Just like hand sanding, you should start with medium-grit sandpaper and slowly progress to ultra-fine grits when using an electric sander. You need to take extra care to avoid heat buildup while you work because electric sanders move faster than your hands and generate more friction.
Electric sanders are fast, affordable, and easy to use, as long as you have the right safety gear (gloves and goggles). Precision work will be impossible with tools like this, which makes hand sanding a better choice for smaller parts.
Polishing of 3D printed parts
Polishing your sanded 3D prints will help you achieve a mirror finish. You don’t need to buy anything special for this to work; products like Brasso make short work of plastics. Simply apply some of your polish to a soft cotton cloth, buffing your 3D print until it’s nice and shiny. Buffing in circles is the best way to maintain a smooth finish.
Chemical smoothing for PLA, PETG and ABS 3D prints
Chemical smoothing for 3D prints eliminates all manual sanding work. A chemical is used to break down the outer layers of the 3D printed object, smoothing it out and reducing the appearance of layer lines. This type of process is quick and efficient, but it can also risk damaging your 3D prints if you make mistakes along the way.
For chemical straightening to work, you need to find a chemical that reacts to the filament material you used. PLA, ABS, and PETG all have different chemical properties, which means different chemicals and methods are used to smooth them. You can learn more about the different types of 3D printable materials in our guide to choosing filament types.
Acetone vapor smoothing for ABS
Like many plastics, ABS can be dissolved in acetone. By exposing an ABS 3D print to acetone vapor, you can smooth its surface in minutes and with very little work. Of course, however, acetone is extremely flammable and toxic, and great caution is required when using it.
You can purchase pre-made acetone vapor chambers designed to work well for 3D print smoothing. Alternatively, you can also build your own acetone vapor chamber using a glass or metal container.
Ethyl acetate smoothing for PLA
Unlike ABS, PLA does not dissolve well in acetone, but it can dissolve in ethyl acetate. Ethyl acetate is the main ingredient in nail polish remover and it has the same flammable properties as acetone. Using nail polish remover is a good choice as it is not very concentrated and is safe to use on the skin.
You can apply ethyl acetate nail polish directly to the surface of your print or use a steam chamber to apply it. It is important to ensure that you clean your 3D print thoroughly after going through this process to avoid a prolonged chemical reaction.
Dichloromethane smoothing for PETG
Its strong chemical resistance is one of the most appreciated characteristics of PETG. It is therefore difficult to find a chemical that can dissolve PETG and provide a smooth finish, but dichloromethane can do the job. Unfortunately, dichloromethane is very dangerous and should only be handled by professionals. For this reason, sanding is generally the best finishing method for PETG.
Using Epoxy Resin for Smoothing 3D Printing
Unlike sanding or using chemical smoothing, epoxy resin adds material to your 3D print to make it smooth. Epoxy is a two-part liquid solution that begins to solidify once the two components are mixed. It can be transparent or colored, and the fact that it starts out as a liquid before becoming a solid makes it ideal for finishing 3D prints. It is not the same type of resin used for SLA 3D printing.
Mix your solution before applying a thin layer to the outside of your 3D print. You can use a brush for this, which makes it easier to get to the tighter parts of your print. Some epoxy resins require curing to solidify properly, so it’s important to read the instructions that came with your resin to get the best results.
Achieve a perfect 3D printed finish
Choosing the right slicer settings and using high quality materials are good ways to improve your 3D prints. Sometimes, however, it makes sense to take extra steps to ensure your 3D prints have the best possible finish. The ideas in this article will help you get started, but you can learn more about 3D printing finishes to take your own models to the next level.