PLA (Polylactic Acid) and ABS (Acrylonitrile Butadiene Styrene) are the most common 3D printing thermoplastics. However, if you want to create a smooth surface on these objects, you must sand them.
PLA is easier to sand than ABS due to its softer nature. However, it is important to sand PLA properly to avoid damaging the surface. When sanding PLA, use very fine grit sandpaper and sand in the direction of the grain.
In this article, I’ll compare the sanding properties of two of the most popular filaments – ABS and PLA – to help you decide which is right for your next project. I’ll also teach you how to sand your 3D prints so you can get a smooth finish every time.
Why Is ABS Harder To Sand Than PLA?
One significant difference between 3D Printed and injection molded parts is the smoothness of the objects. Since 3D-printed objects consist of layers, those layers will almost always have a bumpy, ridge-like texture.
One way to improve the smoothness of your 3D-printed parts is to sand them down.
However, not all 3D printing filaments are equal in sanding. Some filaments are harder to sand than others.
ABS is a typical 3D printing filament with high strength and heat resistance. However, ABS is also known for being difficult to sand. That is because ABS is a dense, hard plastic with a high glass transition temperature.
However, PLA is a bit easier to sand down than ABS. Plus, it’s a bit easier to print with, as it is resistant to warping and prints at a lower temperature than ABS. It may not be as dense, durable, and shiny as ABS, but it is easy to post-process.
However, when sanding PLA, it is best to go easy. You could end up over-sanding if you use highly abrasive sandpaper or drill bits on a PLA object.
The Properties of PLA vs. ABS
PLA and ABS may be the two most popular filaments for beginners, but they don’t have all that much in common.
Here are some notable differences between PLA and ABS:
|Name||Polylactic Acid||Acrylonitrile Butadiene Styrene|
|Ideal Printing Temp||190°C to 220°C||240°C to 270°C|
|Need a Heated Bed?||No||Yes|
|Density||1.3 g/cm3 (81.16 lb/ft3)||1.4 g/cm3 (87.4 lb/ft3)|
|Tensile strength||37 MPa (5,366.4 psi)||27 MPa (3916.02 psi)|
|Special Considerations||None||Prone to warping, releases toxic fumes|
The Ultimate Guide To Sanding PLA or ABS Prints
If you’re trying to achieve a smooth finish on your 3D prints, sanding is one of the best methods. Sanding can be tedious, but it’s worth it in the end.
1. Gather Your Supplies
Here are the supplies you’ll need to gather before you start sanding your PLA or ABS prints:
- Sandpaper in a variety of grits (preferably 120 to 1200-grit)
- A dust mask
- Safety goggles
Note: It’s essential to ensure that the room you’re planning to sand the PLA or ABS prints is well-ventilated and clean.
2. Prepare Your PLA or ABS Prints
When you are finished printing with PLA or ABS, you need to remove any irrelevant parts or debris before sanding the surfaces smoothly.
The best way to remove artifacts, supports, and other unwanted structures is to snap them off with your fingers, then clean up any stubborn marks with flush cutters. You can also use a can of compressed air to blow the irrelevant parts and the debris off of the print.
Once you have removed debris and irrelevant print parts, you can sand the surfaces smooth.
3. Start the Sanding Process
You can sand ABS or PLA by hand or use a machine like a Dremel to help.
However, I recommend avoiding machines like a Dremel if you plan to sand your PLA prints. Sometimes, a drill bit or Dremel can take away too much PLA with one quick swipe. However, ABS is usually challenging to sand, so consider using a machine.
Hand sanding, on the other hand, is the process of using sandpaper to remove material from the surface of a workpiece, and it’s the best method for processing PLA prints. The main advantage of hand sanding is that it is a relatively low-cost method. Additionally, hand sanding generally results in a smoother finish than machine sanding.
Here’s a step-by-step process of sanding PLA or ABS prints using different sandpaper grits:
- Start with 120-grit sandpaper and sand the entire print.
- Move up to 400-grit sandpaper and sand the entire print again.
- Move up to 1200-grit sandpaper and sand the entire print one last time.
It’s important to sand in a consistent direction (preferably circular motion) and to avoid sanding too hard in one spot, as this can create divots in the surface of your prints.
4. Apply Finish to Your PLA or ABS Print
It is important to apply finish to your PLA or ABS print after sanding them to achieve a smooth surface and to protect the print from wear and tear.
There are a few different ways to finish a print, such as using a clear sealer or paint, and each method has its benefits:
- Clear sealers will protect the print and allow the natural colors to shine through.
- You can use paint to add color or change the print’s look.
However, it all depends on the purpose of the print and the look you are going for. Adding a finish is a good idea if you want a professional-looking print that will last a long time.
I highly recommend the Liquitex BASICS Matte Varnish (available on Amazon.com) for sealing your 3D prints. This matte varnish creates a protective shell for your prints, but it also fills in scratches and leaves your objects with a very smooth, durable, and waterproof surface.
PLA is softer and less dense than ABS, which means that PLA is far easier to sand and post-process.
When working with ABS, it’s usually best to use a machine sanding tool, like a Dremel, to wear away the durable filament. However, PLA is fairly simple to sand, and using a machine could take off too much of your print.
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I started 3D printing since 2013 and have learned a lot since then. Because of this I want to share my knowledge of what I have learned in the past years with the community. Currently I own 2 Bambulab X1 Carbon, Prusa SL1S and a Prusa MK3S+. Hope you learn something from my blog after my years of experience in 3D printing.