# Brim or no brim? When a print actually needs one

A brim is a few loops of filament around the first layer. It holds the edges down and stops tall parts tipping. It also costs filament, adds clean-up, and leaves a rough edge on the bottom of the part.

Most prints don't need one.

## The 4 : 1 rule

If a part is **more than four times taller than its narrowest side at the base**, it's likely to wobble or tip as it gets tall. Give it a small brim. Otherwise, leave it off.

| Part | Height : base | Brim? |
| --- | --- | --- |
| 60 × 40 × 30 mm bin | 0.75 : 1 | No |
| 80 × 80 × 100 mm pen cup | 1.25 : 1 | No |
| 10 × 10 × 60 mm post | 6 : 1 | Yes, small |
| 84 mm handle on a 17 mm base | 5 : 1 | Yes, small |

When you do use one, keep it small: about **3 mm wide, outside only, with a 0.1 mm gap** so it snaps off cleanly.

## Other reasons people add a brim (and better fixes)

- **Corners lifting on big flat parts:** clean the bed, slow the first layer and check the bed temperature first.
- **Thin rings and print-in-place parts:** a brim can fuse them together. They usually print fine without one.
- **ABS and ASA warping:** a brim helps here, alongside an enclosure.

Every 3MF you download from MakeMyIdea follows this rule: **no brim**, unless the part passes 4 : 1, and then a 3 mm outer brim. You can see the call in the note under the 3D preview before you download.