What Is a Raft In 3D Printing?

Since first being developed in the early 1980s, 3D printing has come a long way from those early days of high-budget experiments locked away in labs across the world.

With a massive range of uses that have been, and continue to be discovered and be applied to, this exciting new piece of technology is sure to keep making leaps and bounds in the coming years. From the on-site manufacture to using it in pastimes like recreational crafting, to potential uses in medicine and healthcare, there’s no stopping this booming new shiny advancement in our everyday lives!

what is a raft 3D printing

But with a shiny new piece of tech, there also comes a lot of jargon and information along with it. So many new terms to have to understand, and so much more that you need to understand about how they relate to other instructions.

So often, it just feels like there’s no helpful information to help explain what is so different about them. Like, what even is the difference between Polyamide and Polylactic acid? Aren’t they both just plastics for printers? Can they be that different?

Take, for example, the term ‘raft’ as it is used in 3D printing. What does that even mean? And it’s so often used along with other terms that have other meanings outside of 3D printing? What are ‘skirts’ or ‘brims’ in the world of 3D printing?

As overwhelming as all this new information is, it’s important to understand them if you want to make the best use of your brand spanking new piece of tech. Fortunately, we’re here to help separate the rafts from the skirts, and the terms from the jargon, to help you figure out what it is you need to know right now.

What is a Raft?

It’s about time that we explain what exactly the term raft means in the world of 3D printing. Like the kind of outdoor raft you may already be familiar with, a raft in 3D printing is kind of like a floor that is made alongside whatever else you’re printing, and that your 3D printed model will be printed on top of it.

A raft in 3D printing is made out of a horizontal layer of the same filament or printing material you’re using for your printed model and can be changed depending on what settings you have for your printer.

You can add layers to the bottom layers of the raft so that the base that your model is made on is more stable, you can add layers to the top of the raft, to give your printer a smooth surface to build your model on afterward.

Rafts are most often used in the 3D printing process of models that use ABS plastic filament (also known as Acrylonitrile Butadiene Styrene), but they can be used with almost any type of plastic filament that a 3D printer might use. They make a great stabilizing foot for any model, or even a foundation for the rest of your printed piece.

Why is a Raft Necessary?

what is a raft 3D printing

Now, the idea of a raft may seem a little strange at first. Shouldn’t it be possible to just be able to print onto the base of your very expensive 3d printer?

Now, it is possible to ignore using a raft of any kind and just start printing your model onto the printing platform surface. But there are a few good reasons why you should avoid doing this if you can.

Depending on the surface your printer base is on, it can also be tricky to print onto an unsmooth surface for your model. Including a raft in your printer settings means that your model will always start being printed on a flat surface.

Many types of plastic filaments tend to warp as they are being formed at the start of the process, which can be solved by printing the model onto an already existing layer of a filament of some kind, like a raft.

The problem you might face will vary depending on what is being printed, but there is also the issue that some 3D printed models have awkward bases for designs, at least when first being printed into filament.

As the material is still technically setting, a model with smaller or narrower legs or feet may not be able to support the entire weight of whatever the rest of the model turns out to be. Having a large foot or foundation underneath the legs is a great measure to stop your model from buckling before it has even finished printing.

This isn’t to say that there aren’t any drawbacks to using a raft. There’s the obvious problem of the filament you’re using going to waste on a piece of plastic that has no use once the model has finished printing, and separating the raft from the finished model will leave a rough finish under the bottom.

So, it’s worth considering if you do want to use that precious filament for your rafts, or only for particularly difficult models instead.

The Difference Between a Raft, Skirt, and Brims

You may have also come across the terms ‘skirts’ and ‘brims’ when trying to find information around rafts. Although they are often used at the same time when talking about preparing to print your model, they all do quite different tasks.

Skirts, rather than being a base for your model, is an outline of filament that surrounds the model you are printing but does not touch it at all. Skirts are useful because they allow you to make sure your filament is flowing right, and they help prepare your extruder, the part of your 3D printer that manages the processing and moving of the filament you use.

Brims are quite similar to skirts, but they do touch the edge of your model. This is done so that the corners of the model you are building are held down in some fashion, which can help stop the model from bending and warping as it is being printed.

If you aren’t using a raft in your prints, you may want to consider using brims instead, as they do a similar job, but will usually use less filament.

Final Thoughts

From what we’ve seen, rafts might seem like a strange feature to have as part of your 3D printing software, or even a waste of filament.

But as we’ve discussed, they serve a vital function for the printer, helping to make sure you are printing that hot material straight onto the bottom of your printer, or being a good foot for the rest of your model to be printed on.

But we’ve also learned that rafts aren’t the only option available to you, with brims and skirts also being useful tools in your 3D printing arsenal.

Try experimenting for yourself, to see which in-built bases might be best for your model. With a little experimentation, you’ll be printing pristine models in no time at all!

Michael Moore