Brim: the edge that holds a part to the bed

How a brim works

Before the part itself, the printer lays down several continuous lines around its outline, joined to the part. The result is a wide flat rim. It helps with parts that have a small contact area and with materials that shrink. The Prusa Knowledge Base describes it in more detail. A skirt is different, as it does not touch the part, and so is a raft, which is a base under the whole part.

When it is worth it

• Tall, narrow parts that could topple over.
• Parts with little contact, such as a cone standing on its tip.
• Sharp corners that lift at the edges (warping).
• Long thin parts that shrink as they cool.

The cost of a brim

A brim is snapped off after printing, uses a little plastic and adds a little time. After removal a small mark can remain on the bottom edge. For parts where the underside matters, that can be a problem, so we try to avoid it with a better design of the base.

For your order

You do not draw a brim into the model, it is a setting at print preparation. You can also enlarge the contact area in the model, for example with a flat base. A brim does not change the dimensions of the part, because it is snapped off after printing. You see the price right after uploading the model, worked out from the real grams and time. If we see an adhesion problem, we will write to you. See also first layer.

Brim, skirt and raft: the differences

A skirt is a line around the part with no contact, which only primes the extrusion. A brim is a rim attached to the part that holds it. A raft is a thick base under the whole part, used for problem bottoms. A brim is the cheapest way to improve adhesion without changing the underside of the part.

A brim has little effect on the look of the finished part. A snapped-off rim can leave small marks. If a clean underside matters to you, design the part with a flat surface big enough that it does not need a brim.