> For the complete documentation index, see [llms.txt](https://monasheng.gitbook.io/zerotohero/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://monasheng.gitbook.io/zerotohero/3d-printing-zero-to-hero/advanced-skills/advanced-slicing/supports.md).

# Supports

{% embed url="<https://youtu.be/4Fq0th8hkVQ>" %}

{% hint style="info" %}
:man\_mage: **Important:** 3D Printers cannot print into thin air, and must instead first lay-down *support material* in two circumstances:

1. where elements of the part *overhang* at an angle greater than $$45^\circ$$ from the vertical , and,
2. where the part contains otherwise-unsupported *bridges* longer than $$20;\text{mm}$$.
   {% endhint %}

## Overhangs

As is the case for 'Y' and 'T' shapes, overhanging areas in parts leave a gap to the build plate that can be troublesome when 3D printing. In general, any overhang at an angle greater than $$45^\circ$$ from the vertical will require supports to avoid the molten plastic simply falling through the air when printing.

<figure><img src="/files/0fqnVRr0DXzBTvadjY2F" alt=""><figcaption></figcaption></figure>

Supports are generally not required for overhangs less than $$45^\circ$$ to the vertical, as these grow upward faster than they grow outward - meaning that there is sufficient purchase on the previous layer to support the overhang while the plastic cools.

<figure><img src="/files/crOyfAJr2jQMlyTAIYCe" alt=""><figcaption></figcaption></figure>

## Bridges

For the same reason, supports are required wherever a part has a *bridge* - essentially an overhang supported from two sides. Because they are dually-supported, some bridges can be spanned by a 3D printer even if the angle is greater than $$45^\circ$$ to the vertical (e.g. when fully horizontal). Ordinarily, bridges  $$<20;\text{mm}$$ long can be printed without supports.

<figure><img src="/files/agP2IWduVubllK8EkZBf" alt=""><figcaption></figcaption></figure>

## Support Settings

Most slicer programs allow some automatic generation of supports, and control of the way that these are added. For instance, the quick-access settings panel in *PrusaSlicer* allows you to:&#x20;

* add supports *everywhere* that a large bridge or shallow overhang exists,
* add supports only to large bridges or shallow overhangs that are *above the build plate* (i.e. not between elements of a part), or,
* place *no supports* at all.

It also allows you to manually specify specific locations you want supports called *support enforcers*. You can define regions to allows supports using box/cylinder/sphere volumes.

## Trade-offs

Adding supports to your prints will use extra filament, take more time to print, and require some post-processing of the part to remove, but is *essential* for shallow overhangs and large bridges. Unsupported prints will more than likely fail in most cases. You should aim to minimise the need for supports wherever possible, by:

1. modifying the design to eliminate troublesome features,
2. altering the [Part Orientation](/zerotohero/3d-printing-zero-to-hero/advanced-skills/advanced-slicing/part-orientation.md) to place otherwise unsupported regions in-plane, or,
3. splitting the part to print in sections and re-attaching these afterward - see [Advanced Joinery](/zerotohero/3d-printing-zero-to-hero/advanced-skills/advanced-joinery.md).

Sometimes, this is simply not possible - perhaps a design is locked and a particular orientation is required for [Part Orientation](/zerotohero/3d-printing-zero-to-hero/advanced-skills/advanced-slicing/part-orientation.md#strength). In these cases, you may need to implement supports and deal with the larger print time.