3D FDM printers work by depositing layers of filament on a print bed. The first layer of filament deposited plays a critical part in making sure the print turns out well. Depending on what filament is used, getting that first layer to stick to the print bed can be difficult.
Poor first-layer adhesion typically produces warped or failed prints. There are several ways to prevent this from happening, one of which is to use a heated print bed. Heated beds have become a standard feature of 3D printers, especially if you are going to print using materials with high melting points like nylon.
Heated beds are by no means the only way to improve the odds of turning out a perfect print. Brims are another way of ensuring your prints go smoothly. But what exactly are brims and how do they work?
What Does A Brim Do In 3D Printing?
Brims are supports used to improve the first layer adhesion of a 3D print as well as test the extrusion of material before printing the actual design. Along with other types of supports like rafts and skirts, brims reduce problems like warping.
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Brims are created through the settings in your slicer software. They are generally one layer tall and attached to the print to provide better surface adhesion. Brims are printed as part of the print. This is especially important for prints that have irregular shapes. Source
Using slicer settings you can control:
- Brim width which controls how wide your brim fans out around your print. Increasing the width of your brim generally improves the layer adhesion of your print.
- Brim lines set how many lines your brim will have.
Brims are similar to rafts. Rafts are also supports but the main difference between rafts and brims is that rafts start from underneath the print to form a pedestal on which the print sits. Brims start from the outer edge of a print.
Without a brim, prints with complex geometries are almost impossible to create as they can’t adhere to the print bed due to low print-to-surface area contact. This increases the chances of layers splitting apart and even the print falling off the print bed altogether.
Brims also allow you to calibrate your printer. Rather than start printing directly, you can first start by printing a brim to calibrate your printer settings like temperature and to check if your bed is level. This can save you time and material.
Pros Of Using A Brim
- Improved layer adhesion reduces the likelihood of warping. This is important for printing materials like ABS which are especially prone to warping.
- Brims use less material than rafts while providing as much support.
Cons Of Using A Brim
- While brims use less material than rafts, they use considerably more than skirts which can create material waste.
- They add to the build time due to the need for more post-processing. The brim has to be cut or broken from the print to remove it. This is a time-consuming task.
Is Brim Or Skirt Better?
Skirts perform the same function as brims. They help improve first-layer adhesion when used to test and find the right printer settings for a specific material. The main difference between them is that skirts are not connected to the print. In that sense, skirts provide less support to the print than brims.
What Is A Skirt For When 3D Printing?
Skirts are printed before the design. Like brims, printing the skirt first allows you to test if the filament is extruding properly before you move on to the design. Unlike brims, however, skirts are printed around the design and do not form part of the design. Source
Skirts allow you to check the bed adhesion and surface levels before you start printing. Using slicer settings, you can control
- Line count which is the number of lines you want the skirt to have. A useful way to use this is to print more than one line if you have or want to change the settings as when you switch between materials for example.
- The distance between your skirt and print.
- The number of layers for your skirt.
Pros Of Using A Skirt
- Skirts use far less material than a brim.
- Skirts also reduce the time spent on post-processing. Since they are not attached to the print, you do not have to spend time trying to remove them.
Cons Of Using A Skirt
- As they are not attached to the print, skirts do not provide physical support to a print.
So which should you use between a skirt and brim? It depends on your print. For example, if you are working with a print with a highly irregular shape, a brim will provide much-needed support. A skirt will provide you with none.
On the other hand, if you are printing a large model, you might be better off printing a skirt if you are not sure if you have enough material.
How Do You Easily Remove Brims?
Brims improve layer adhesion at the expense of adding to the build time. Not only is more material extruded, but removing the brims can be difficult and increases the time spent in post-processing. Two of the simplest ways to remove a brim are to either sand it down or break it off with the use of a tool like a knife or needle-nose pliers.
Tools are particularly useful for small prints or prints with twists and angles that make the supports harder to access. Armed with the right tool you can easily cut or break off the support in areas where your hands or fingers cannot reach.
With that said, you also want to make brims or any other type of support you use easier to work with. One way to do that is to design or orient your print during printing in a way that minimizes the need for support.
Try printing your model from an angle that naturally provides better support. For example, printing a “T” upside down removes the need for supports.
Another very effective way to make supports easier to remove is to print them in a soluble material like PVA for example. PVA dissolves in water so once you are done with your print, all you have to do to remove your PVA supports is soak the print. This method only works best for dual extruders.