Key Takeaways

  • Adjust print temperature: Lower your extrusion and bed temperature to avoid overheating and spilling of filament.
  • Reduce vibration: Tighten your printer’s frame, screws, bolts, and pulleys to prevent unwanted movement and wobbling.
  • Lower print speed: Give each layer enough time to solidify and adhere before adding the next one.
  • Post-process your prints: Use sanding, filling, priming, painting, or acetone vapor smoothing to remove or hide the lines.

A major part of 3D printing is aethetic appeal, especially when printing for decorative purposes. The appearance of unwanted blobs and zits, ghosting, and lines in your prints ruins a model’s look and become a real nuisance if left unfixed.

In this article we’ll look at why these lines form, how much of a problem they can be, as well as the different causes and solutions to the unsightly issue.

Causes and How To Elimate Lines In 3D Prints

Why 3D Printed Parts Have Lines

3D printed parts have lines because 3D printers work by depositing layer after layer of filament or resin on top of each other until achieving the desired shape. So, a finished piece can have hundreds or thousands of individual layers, depending on your chosen layer height.

These layers of filament are often visible, but if they are large or uneven, that can be a sign that something is going wrong during printing.

Here’s the difference between normal lines and problematic ones:

Normal lines

Normal print lines
Source: Reddit

Small horizontal lines on the side of a 3D printed part are usually nothing to worry about. These lines are a natural part of the FDM 3D printing process, and won’t affect the model’s functionality.

If you want a completely smooth surface, you can create your ideal finish. Acetone vapor smoothing is a very effective way to smooth the small horizontal lines on your finished 3D printed parts, especially with ABS.

Problematic lines

Unwanted, problematic lines in 3D printing will seem random and even bulge out from the model itself. These lines ruin your print’s aesthetic and can be hard to remove, leading to a failed print and wasted filament.

How To Eliminate Layer Lines in 3D Prints

So if you’ve found these lines on your prints, here are the reasons below, with our solution to each to get your models back to looking their best.

1. Printing Too Hot

This was caused by filament issues
Source: Reddit


If your printing temperature is set too high, then your filament will stay overheated as it’s layered. This means it will take longer to cool down and properly solidify before the next layer is added, meaning it won’t set – and the filament will spill out and form unwanted lines.


Lower your extrusion temperature in 5℃ increments and print a test print to find the best temperature for your filament. Once you stop seeing lines, and the filament seems to be layering properly, take note of the temperature setting so you know which to use.

As an extra precaution, it’s also worth adjusting the temperature of your heated bed – if you’re using one. This is especially important if you’re only noticing issues in the initial layers.

2. Mechanical Issues

Mechanical Issues
Caused by wobbling hotend due to a loose bolt. Credit: Gordon Tarpley


To get the most aesthetically pleasing results, filament needs to be layered smoothly. This means that you may find lines in your prints if there’s too much vibration during printing.

Unwanted vibration is usually a hardware issue. If your printer’s frame isn’t tight enough, then the parts will move and jerk too much mid-print and the filament won’t layer properly. These vibrations could be imperceptible to the naked eye, so this could be your issue – whether you’ve noticed it or not.


The first step to getting rid of these vibrations is to ensure your printer is set on a sturdy, even surface to reduce even slight movement while printing.

Some surfaces are better than others, such as tables and desks. We have previously written an article on the best 3D printer tables and surfaces, if you think this might be a problem for you.

Once you’re sure of this, it’s a good idea to switch off and unplug your printer and then check over it, tightening any screws, bolts, or pulleys that seem to have come loose. These parts will loosen over time and use, so it’s a good idea to check over your printer’s frame every 5-10 prints just to be sure.

Finally, make sure your axes are set correctly and the extruder is moving as it should. You may need to recalibrate your axis settings or clean them if you find the issue continues.

3. Print Speed Too High

Print Speed Too High
Source: Reddit


Each layer of your print needs enough time to properly set and adhere so the next one can be printed evenly and neatly. Printing too fast means the filament doesn’t have enough time to sufficiently solidify, meaning the following layer will be printed on an unstable surface.

It may be tempting to print at the maximum recommended speed to get your print done faster, but overly high print speeds can lead to a variety of issues, including lines.

This filament will become misshapen and deviate from the desired path, leading to visible horizontal lines between these layers.


Lower print speeds tend to lead to more accurate prints. Lowering your print speed is a good way to get rid of these lines, as well as any other layering problems you may be experiencing.

It’s also worth remembering that it may not just be the printing speed that’s too high. Lowering your retraction speed between layers may also help you get more reliable prints.

Why do my 3D prints have horizontal lines?

3D printed parts are printed layer by layer. These lines are usually visible on a finished piece but can be smoothed or polished off. If the lines on your print are too large that can be a sign of a problem in your printing process. You may be printing too hot, too fast, or having mechanical issues.

How do you get rid of 3D printing lines?

To get rid of normal lines that occur on 3D printed pieces, the piece needs to be smoothed. Lines can be polished out physically with some fine grit sandpaper, or chemically with acetone vapor. If the lines on your part are large or unusual you have a problem with your printing process and need to address the root of the problem.

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