What Is a Brim in 3D Printing? The Complete 2025 Guide

First Layer Basics

Every 3D printing fan knows this feeling: hours into a print, you hear a terrible sound—the nozzle hitting a piece that came loose. Or even worse, you come back to a finished print only to find the corners have lifted off the build plate. This annoying problem is called warping. A perfectly designed model is useless if it can't stick to the bed.

The answer is often a simple checkbox in your slicer software: the brim. This feature is an incredibly helpful tool for solving these basic printing problems. In this guide, we will cover everything you need to become an expert on using a 3D printing brim. You will learn what a brim is, how it's different from a skirt or raft, exactly when to use one, how to adjust its settings for the best results, and the best ways to remove it cleanly.

The Basic Brim Idea

Understanding what a brim is and why it works is the first step toward stopping first-layer failures. It's a simple idea with a powerful effect on print success.

A Print's Built-in Anchor

So, what is a brim in 3d printing? Think of it like the brim of a hat, but laid flat on the build plate and attached to your print. Technically, a brim is a series of circles of plastic printed around the outside of your model's first layer, directly connected to the model's edge. It makes the base of your object bigger, creating one solid piece for the first layer.

This bigger base acts as a helper anchor. Its only job is to hold your model firmly to the build plate while printing. Once the print is done, the brim is carefully removed and thrown away.

The Science of Sticking

The main reason prints fail at the bottom is heat shrinking. As the melted plastic comes out and cools down, it gets smaller. This shrinking creates stress inside the model. On a print with sharp corners or long, straight edges, this stress pulls inward, causing the corners and edges to lift away from the build plate. This is warping.

A 3D printing brim fights this force through one simple rule: more surface area. By making the part of the print that touches the build plate much bigger, it creates a much stronger bond. This larger base spreads the pulling forces over a wider area, effectively holding the model down and stopping the edges from lifting.

Brim vs. Skirt vs. Raft

Slicer software offers three main tools for build plate sticking: skirts, brims, and rafts. Mixing them up can lead to print failures, so understanding what each one does is important for every maker.

A Key Comparison

Each tool serves a different purpose, ranging from a simple pre-print check to a complete base structure. Choosing the right one depends on your model, material, and printer.

The Skirt: A Nozzle Primer

A skirt is an outline that is printed around the model but does not touch it. Its only purpose is to get the extruder ready. As the skirt prints, it stabilizes pressure in the nozzle and makes sure a smooth, steady flow of plastic is ready the moment the printer starts on the actual model. It's a pre-flight check for your extruder, not a sticking aid for your part.

The Brim: Sticking Helper

As we've talked about, a brim is an extension of the first layer that touches the model's edge. Its specific job is to provide extra surface area to improve bed sticking and prevent warping. It is the go-to solution for parts that tend to lift but otherwise have a fairly flat bottom.

The Raft: A Full Foundation

A raft is a complete, separate grid of plastic printed underneath the entire model. The model is then printed on top of this raft, not on the build plate itself. A raft is the strongest sticking solution. It's used for models with very small contact points (like a figure standing on its tiptoes), materials that warp easily like ABS on an open-frame printer, or when printing on a damaged or uneven build surface.

Quick Comparison

To make the choice easier, here is a direct comparison of the three sticking tools.

Feature	Skirt	Brim	Raft
Main Purpose	Prime Nozzle	Prevent Warping/Sticking	Max Sticking/Base Foundation
Touches Model?	No	Yes, on the sides	Yes, on the bottom
Plastic Usage	Very Low	Low-Medium	High
Print Time Impact	Very Small	Low	Big
Clean-up	None	Needs removal from sides	Needs removal from bottom

When to Use a Brim

Knowing when to turn on a brim—and just as importantly, when not to—is a key skill that saves time, material, and frustration.

Green Light: Use a Brim

A brim is your best friend in several common printing situations. We recommend turning on a brim when:

• You Print Tall, Thin Models: Objects like towers, skinny figurines, or posts have a high center of gravity and a small base. A brim provides a wider, more stable foundation, preventing them from being knocked over by the nozzle during printing.
• The Model Has Small Contact Points: If your model has legs, points, or any delicate features touching the build plate, a brim is essential. It connects these small anchor points, creating a unified and secure base.
• You See Corner Lifting: This is the classic sign that you need a brim. If you've ever printed a rectangular box and found the corners curling up, a brim is the direct solution.
• Working with Warp-Prone Materials: Materials with a high shrinkage rate are prime candidates for warping. A brim is highly recommended for ABS, ASA, and Nylon. It can also be helpful for large PETG prints, depending on their shape.
• Printing a Long, Important Part: If you are starting a multi-day print or a part where failure is not an option, adding a brim is a cheap and effective insurance policy against sticking failure.

Red Light: Skip the Brim

A brim is not always necessary and sometimes can be harmful. You can confidently skip the brim when:

• The Model Has a Large, Flat Base: If your print has a big surface area already in contact with the bed, it likely has enough natural sticking to stay put.
• Bottom Surface Looks Are Most Important: A brim always leaves a small mark or "witness line" where it was attached. Even with careful removal, the bottom edge will not be as perfect as a part printed without one. If the bottom surface must be flawless, try to print without a brim if possible.
• Using Easy-Sticking Materials: PLA is famously forgiving and often sticks very well to common build surfaces like PEI, glass, or textured sheets without any extra help.
• You're Quick Prototyping: For quick, non-critical test prints where speed is the priority and a little bit of corner lift is acceptable, skipping the brim will save a small amount of time and material.

How to Set Up Brims

Mastering the brim requires a quick trip into your slicer's settings. These options are usually found under a tab labeled "Build Plate Adhesion." While defaults are a good start, adjusting them unlocks a perfect balance of strong sticking and easy removal.

The Essential Settings

The most basic setting controls the size of your brim.

• Brim Line Count (or Brim Width): This setting determines how wide the brim is by setting the number of circles. A typical starting point for most prints is between 8 and 12 lines. For a standard 0.4mm nozzle, this creates a brim 3-5mm wide. If you are still experiencing warping, increase the line count. More lines equal more sticking, but also more material use and a bit more effort in clean-up.

The Expert-Level Setting

For easy removal, this is the most important setting to master.

• Brim Separation Gap (or Brim Distance): This setting defines a tiny, controlled air gap between the last line of the brim and the first wall of your model. It's the secret to a brim that holds strong during printing but peels away cleanly afterward. A value of 0.0mm means the brim will be fully fused to your part, making it very difficult to remove. A value that is too large will create a gap, and the brim will not provide any support.

  A starting value between 0.1mm and 0.15mm is ideal for most setups. We strongly advise printing a small, simple test cube with a brim to tune this setting. Adjust it by 0.02mm steps until you find the sweet spot where the brim holds firmly but can be peeled off with minimal effort. This small calibration will save you huge clean-up headaches.

The Art of Brim Removal

A printed part with a brim is not a finished part. Removing it cleanly is a skill that separates a good print from a great one. This is often a source of frustration for beginners, but with the right tools and techniques, it becomes a simple and satisfying process.

Your Finishing Toolkit

Having a few dedicated tools makes brim removal fast, safe, and effective.

• Deburring Tool: This is the undisputed champion for cleaning up the edge left by a brim. It features a free-spinning, curved blade that naturally follows the edge of your part, shaving off the brim remnant in a smooth, clean pass.
• Hobby Knife / Scalpel: A sharp, pointed blade is essential for getting into tight corners or cleaning up small areas where a deburring tool can't reach. Always use a fresh, sharp blade for the best results.
• Flush Cutters: These are useful for snipping away large sections of the brim, especially on complex parts, before moving on to finer tools. They help break the brim into more manageable pieces.
• Sandpaper or Small Files: A small piece of 220 or 400-grit sandpaper or a set of needle files is perfect for the final touch-up, smoothing the bottom edge to perfection.

Step-by-Step Removal

Follow this process for a professional finish every time.

1. The Flex & Peel: Start by gently bending the brim away from the part. For more brittle materials like PLA, this can often cause the brim to snap off cleanly along the separation gap, especially if your settings are well-tuned.
2. The Deburring Pass: This is the most effective technique. Hold the part firmly. Place the deburring tool's blade against the bottom edge where the brim was attached. Apply light, consistent pressure and run the tool along the entire edge. The curved blade will catch the lip of the brim and shave it off in a single, continuous strip, leaving a perfectly smooth edge.
3. Precision Cutting: For any remaining bits in sharp corners or internal cutouts, use a hobby knife. Always place the part on a stable surface and cut away from your body and fingers. Use light, scraping motions rather than forceful cuts.
4. Final Sanding: If any roughness remains, a few light passes with fine-grit sandpaper or a file will smooth the bottom edge, making the brim's former presence nearly invisible.

Fixing Brim Problems

Even with a brim, problems can arise. Here's how to solve the most common issues like an expert.

• Problem: My brim is stuck to my part!

  • Solution: This is the most common complaint and is almost always caused by an incorrect separation gap. Your "Brim Separation Gap" is set to zero or is too small. Increase the gap in your slicer (e.g., from 0.1mm to 0.15mm). Over-extrusion can also contribute to this, so performing an extrusion multiplier or flow rate calibration is a good secondary step.

• Problem: My part still warped with a brim.

  • Solution: The warping forces are overpowering your brim's hold. The first step is to increase the "Brim Line Count" to create a wider, stronger anchor. A 15-20 line brim offers significantly more sticking. If warping continues, the issue is likely environmental. Check for cold drafts from windows or AC units. For materials like ABS or ASA, using a draft shield (another slicer setting) or a full printer enclosure is often necessary to maintain a stable room temperature.

• Problem: The brim itself isn't sticking.

  • Solution: This indicates a basic first-layer sticking problem, not a brim-specific issue. The brim is your warning sign. First, re-level your build plate. Second, and more importantly, verify your Z-offset. If the nozzle is too far from the bed, the plastic won't be "squished" enough to stick properly. Finally, ensure your build surface is perfectly clean. Wipe it down with a high-concentration isopropyl alcohol before every print.

The Brim: Your Friend for Success

As we've seen, a 3D printing brim is a simple but exceptionally powerful tool. It is the frontline defense against warping, the stabilizer for tall and delicate models, and the insurance policy for critical prints.

Understanding what is a brim in 3d printing, when to use it, and how to tune it is a basic skill that elevates a maker from beginner to experienced operator. It's the key to transforming frustrating failures into consistent, reliable success. We encourage you to load a small test model, experiment with your brim settings, and find the perfect balance of sticking and easy removal for your machine. This small investment in time will pay dividends in successful prints for 2025 and beyond.

Frequently Asked Questions

• Q1: How much extra plastic does a brim use?

  • A: Very little. A brim is typically only one or two layers high and exists only at the edge. Its material cost is negligible, especially when compared to the cost of a failed print. It uses far less plastic than a raft.

• Q2: Can I use a brim and supports at the same time?

  • A: Yes, absolutely. They serve completely different functions and are often used together. The brim anchors the entire base of the model to the build plate, while supports are generated to hold up overhangs and steep angles higher up on the model. Your slicer will intelligently generate both.

• Q3: Is a brim always better than a raft?

  • A: Not always, but it is the more efficient choice for most situations. A brim should be your first option for solving common warping and sticking issues. A raft is a more extreme solution, better suited for parts with almost no surface contact with the bed, or when printing on a severely uneven or non-ideal build surface. As a rule of thumb: try a brim first. Only use a raft if the brim fails.

• Q4: Does a brim leave a permanent mark?

  • A: It will always leave a trace or "witness line" where it was attached. However, the visibility of this mark is directly related to your settings and removal technique. With a properly tuned "Brim Separation Gap" and skillful use of a deburring tool, this mark can be reduced to a clean, subtle edge that is nearly invisible and does not detract from the final part's quality.