> 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-joinery/threaded-inserts-and-non-permanent-fasteners.md).

# Threaded Inserts & Non-Permanent Fasteners

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:man\_mage: **Important:** You need not only join prints with glue - a range of non-permanent mounting techniques exist - including the use of fasteners, threaded inserts, and cable ties!
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## Screwing and Tapping

We will ordinarily *not* print threads directly into parts, owing to the level of detail required and limited strength that we can achieve. Instead, we usually add threads to parts in post-processing.

3D prints are only plastic - and thus you can easily provision a thread in them using conventional drill-and-tap method.&#x20;

You can also directly cut threads into most prints with a self-tapping or wood screw. In both cases, the strength of threads is limited by the material, and threads can loosen with repeated cycles.

## Threaded Heat-Sunk Inserts

To provision slightly more robust threads in your 3D prints, you can purchase brass *threaded inserts* that you *melt in* using a soldering iron.

<figure><img src="/files/7HFsIfz4OI1g4JlSA5Ne" alt=""><figcaption><p>Left: a typical brass threaded insert. Centre: Sinking the insert using a soldering iron. It heats the insert, which melts the plastic around it. Right: a finished part, featuring 4 inserts.</p></figcaption></figure>

Inserts typically feature a knurled section that grips onto molten plastic and interlocks with it as it cools. You will ordinary slightly undersize holes for threaded inserts in your part, to allow some excess plastic for this gripping. Once set, sunk inserts are typically fairly well 'locked in'.

While in a pinch you can sink inserts with any old soldering iron tip, there are tips designed specifically for this purpose.

<figure><img src="/files/dubSYhX3dVATwmOJ3NN3" alt=""><figcaption><p>A soldering iron tip specifically designed for heat-sunk threaded inserts.</p></figcaption></figure>

## Extension Content

There are also other ways to non-permanently fasten your prints.

Cable ties are a popular option as they are quick, cheap, and you only need to model holes for them to thread through. The print head of most prusas are actually cable tied to the frame.

<figure><img src="/files/3873LpSQpscw67gQA5DH" alt=""><figcaption><p>Cable ties fastening the print head of a Prusa MK2S to linear bearings.</p></figcaption></figure>

Magnets are another option, but they won't fasten your parts together too strongly so be wary. They are a great choice to embed into lids or other parts that will frequently be separated.

<figure><img src="/files/bnYNW7xooH0aydcZBX40" alt=""><figcaption><p>A 3d printed box with small magnets embedded to hold the lid on.</p></figcaption></figure>

Velcro is another great way to fasten prints that will frequently be separated. Either looping it around parts in a belt fashion, or by applying self-adhesive velcro to the surfaces of the parts you wish to fasten.

<figure><img src="/files/vKQpz9oCznAnRagJWZBD" alt=""><figcaption><p>A 3d printed battery mount with velcro straps to secure the battery and self adhesive velcro strips</p></figcaption></figure>

A professional method of fastening parts is through snap-fit joints. This is when you leverage the flexibility of plastic and design features in your prints to clip them together. There are countless ways to achieve this, but it is a skill that requires a great deal of knowledge in CAD modelling and 3D printing.

This approach is not for the feint-hearted, but if you are interested [here is a good guide. ](https://all3dp.com/2/3d-printing-snap-fit-design-simply-explained/)