> For the complete documentation index, see [llms.txt](https://lessons.mistyrobotics.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://lessons.mistyrobotics.com/hardware-extension/misty-arm.md).

# Misty arm

On this page, you will be able to download the .stl files containing the models for 3D printing your Misty arm.

#### .stl files: 

{% file src="/files/HRYn8fnsJPVvPdpcE8PH" %}

{% file src="/files/lKM7cPd5tGWO91Qw4Mpb" %}

{% file src="/files/IaPnSvfkXrLMzdZHqgx8" %}

<div><figure><img src="/files/uRE7REqA4VDn2gSgwTMv" alt="" width="375"><figcaption><p>arm</p></figcaption></figure> <figure><img src="/files/Z8XxdPyIByekG100SBOx" alt="" width="200"><figcaption><p>gear</p></figcaption></figure> <figure><img src="/files/yEmDI8OGqNj50O9V1t8x" alt="" width="375"><figcaption><p>mobile</p></figcaption></figure></div>

#### Adjustments

The front part of the arm has been developed to be completely customized.&#x20;

In fact, we want to have the possibility to have different tools but not to print a new arm every time.  To solve this we inserted a negative M - of Misty - where you can put the front part that suits your needs better. For example, we chose to insert this [gripper](https://www.thingiverse.com/thing:5149951) - I modified the size of the two gears of the gripper to 103% to have a better fit.&#x20;

We modified the base of the gripper deleting the behind wall and inserting a positive M that matches with the mobile one.

<figure><img src="/files/Hc91DxOsb9LnlmhNZ38J" alt="" width="375"><figcaption><p>Modified base of the gripper</p></figcaption></figure>

{% file src="/files/vWj3vVPMIQTZ67ncOSAF" %}
M letter for matching pieces
{% endfile %}

{% file src="/files/U9fUeku0pwfQwRcdd5Cq" %}

The servo motors that we'll use in this project are the positional SG90.&#x20;

#### Assembly

1. **Prepare the new arm** \
   \- Screw the SG90 servo motor in the arm with the small gear towards the outside part. \
   \- Slice the mobile part in the arm. \
   \- Insert the gear in the servo motor (the gear will rotate in the middle part of the rail, so you don't need to insert it from the very beginning of the gear)\
   \- Insert your front part in the mobile.&#x20;
2. **Screw the new arm**\
   **-** Unscrew the old arm. \
   \- With the same screw insert the new 3d printed arm.

<div><figure><img src="/files/BQKOlBPvru63lkMm55Eu" alt="" width="188"><figcaption><p>arm</p></figcaption></figure> <figure><img src="/files/5uGxwMT3LsZLfGeUnmAQ" alt="" width="188"><figcaption><p>mobile part and gear</p></figcaption></figure></div>

<figure><img src="/files/IAiARyV7kRFlVdFdizuJ" alt="" width="375"><figcaption><p>complete arm</p></figcaption></figure>

#### Pictures

<div><figure><img src="/files/rNlRm5ffkmfSM7U7ofdx" alt=""><figcaption><p>arm extension</p></figcaption></figure> <figure><img src="/files/3xVFTrTIySlLccFwXsy0" alt=""><figcaption><p>side picture with cup holder</p></figcaption></figure></div>

<div><figure><img src="/files/5duujNZwTeOhVy8lHiDL" alt=""><figcaption><p>arm</p></figcaption></figure> <figure><img src="/files/K6KBfF9LhAmadbvTqSoy" alt=""><figcaption><p>standard position</p></figcaption></figure></div>