# Details Center Pulley Preparation
<img src="../images/pulley_preparation_1.jpg" width="300"> <br>*Starting Point: Center Pulley and Timing Belt Tensioner Components*  

<img src="../images/pulley_preparation_1_1.jpg" width="300"> <br>*End Result: Center Pulley and Timing Belt Tensioners assembled*  

## Description
* This page describes how to prepare the center pulley and the timing belt tensioners for the brushless actuator modules
* The center pulley consits of the 10 tooth aluminium pulley and the 30 tooth 3d printed pulley.
* The pulleys are press-fit using an arbor press and 3d printed tools. [-> Press-Fitting the Pulleys](#press-fitting-the-pulleys)
* The timing belt tensioners are prepared and assembled. [-> Assembling the Timing Belt Tensioners](#assembling-the-timing-belt-tensioners)    

### More Information
* More information on the 3d printing: [Details 3d Printed Parts](details_3d_printed_parts.md#details-3d-printed-parts)  
* More information on the machined part: [Details Machined Parts](details_machined_parts.md#details-machined-parts)
* [PDF File - Pulley AT3 T10 Center](../drawings/center_pulley_at3_t10.PDF)
* [STL File - Pulley AT3 T30 Center](../stl_files/transmission_pulley_at3_t30_center.STL)
* [STL File - Timing Belt Tensioner Rollers 10mm](../stl_files/transmission_belt_tensioner_roller_10.0mm.STL)
* [STL File - Tool Center Pulley Protection](../stl_files/tool_center_pulley_protection.STL)
* [STL File - Tool Center Pulley Assembly](../stl_files/tool_center_pulley_assembly.STL)

## Press-Fitting the Pulleys

<img src="../images/pulley_preparation_1_2.jpg" width="300"> <br>*Apply a bit of Loctite 648 onto the internal tooth profile of the 3d printed pulley.*

<img src="../images/pulley_preparation_2_1.jpg" width="300"> <br>*Place the aluminum pulley on the 3d printed pulley. <br> Make sure it's vertical and matches the tooth pattern. <br> Push it in a bit by hand - the centering hole should be facing upwards.*  

<img src="../images/pulley_preparation_2_2.jpg" width="300"> <br>*Make sure that the centering hole is facing upwards.*

<img src="../images/pulley_preparation_3_1.jpg" width="300"> <br>*Place the 3d printed protection tool on the aluminum pulley.*

<img src="../images/pulley_preparation_4_1.jpg" width="300"> <br>*Turn your assembly around.<br> Place and center the 3d printed assembly tool on the bottom side.*

<img src="../images/arbor_press.jpg" width="300"> <br>*We use an arbor press to join the parts.*

<img src="../images/pulley_preparation_5_1.jpg" width="300"> <br>*Alternative: You can also use a vise to press-fit the parts.*

<img src="../images/pulley_preparation_5.jpg" width="300"> <br>*Place your stack of parts on the arbor press. <br>Slowly push the aluminum pulley all the way down.*

<img src="../images/pulley_preparation_5_2.jpg" width="300"> <br>*Remove the protection and the assembly tool.<br>Use a cotton swab to remove excess Loctite.*

<img src="../images/pulley_preparation_6_1.jpg" width="300"> <br>*The parts should be flush on the bottom side. <br>Remove scraped-off material with a tooth brush.<br> Use the arbor press again if the parts don't line up.*

<img src="../images/pulley_preparation_7_1.jpg" width="300"> <br>*The center pulley is now ready for installation.*

## Assembling the Timing Belt Tensioners
<img src="../images/pulley_preparation_8_1.jpg" width="300"> <br>*Timing belt tensioner bearings and 3d printed rollers.<br>For each actuator module two timing belt tensioner assemblies are required.<br>We use the 10mm diameter roller as default size.<br>Larger roller diameters can be used to adjust the timing belt tension.*

<img src="../images/pulley_preparation_8_2.jpg" width="300"> <br>*Place the bearings on the 3d printed rollers.*

<img src="../images/pulley_preparation_8_3.jpg" width="300"> <br>*Turn the parts around and push the roller onto the bearing.*

<img src="../images/pulley_preparation_8_4.jpg" width="300"> <br>*Make sure that the bearings are inserted all the way.*

<img src="../images/pulley_preparation_8_7.jpg" width="300"> <br>*We use stainless steel washers as a rigid surface for supporting the inner ring of the bearing.<br>We use M3 screws but M3 washers are too large and prevent the outer ring of the bearing to rotate freely.<br>Therefore we modify M2,5 washers to fit the M3 screws.*

<img src="../images/pulley_preparation_8_5.jpg" width="300"> <br>*The M2,5 washers have the following dimensions: ID 2,7mm / OD 5,8mm<br>Use a round file to evenly increase the inner diameter of the washer to about 3mm.<br>*

<img src="../images/pulley_preparation_8_6.jpg" width="300"> <br>*Timing belt tensioner, M3x10 flat head screw and modified M2,5 washer.*

<img src="../images/pulley_preparation_8_8.jpg" width="300"> <br>*Insert the M3 screw into the side with the ledge as shown in the picture.<br>Turn the assembly around and install the modified M2,5 washers.*

<img src="../images/pulley_preparation_1_1.jpg" width="300"> <br>*The center pulley and the two timing belt tensioners are now ready for assembly.*

---
## Step-by-Step Instructions

| Motor Preparation  | Motor Shaft Preparation | Encoder Preparation |Center Pulley Preparation|
| --- | --- | --- | --- |
| <a href="details_motor_preparation.md#details-motor-preparation"><img src="../images/motor_mod_1_1.jpg" width="200"></a>| <a href="details_motor_shaft_preparation.md#details-motor-shaft-preparation"><img src="../images/motor_shaft_preparation_18.jpg" width="200"></a>  | <a href="details_encoder_preparation.md#details-encoder-preparation"><img src="../images/encoder_1.jpg" width="200"></a>  |<a href="details_center_pulley_preparation.md#details-center-pulley-preparation"><img src="../images/pulley_preparation_1_1.jpg" width="200"></a> |

| Output Pulley Preparation | Shell Preparation | Actuator Module Assembly |Actuator Module Testing|
| --- | --- | --- | --- |
| <a href="details_output_pulley_preparation.md#details-output-pulley-preparation"><img src="../images/output_pulley_preparation_9.jpg" width="200"></a>| <a href="details_shell_preparation.md#details-shell-preparation"><img src="../../leg_2dof_v1/images/shells_1.jpg" width="200"></a>  | <a href="details_actuator_module_assembly.md#details-actuator-module-assembly"><img src="../images/actuator_module_open_1.jpg" width="200"></a>  |<a href="details_actuator_module_testing.md#details-actuator-module-testing"><img src="../images/actuator_module_1.png" width="200"></a> |

---
## More Details
| Details 3d Printed Parts | Details Machined Parts | Mechanical Tools and Consumables |Electronic Components and Tools|
| --- | --- | --- | --- |
|<a href="details_3d_printed_parts.md#details-3d-printed-parts"><img src="../images/3d_printed_parts_2.jpg" width="200"></a>|<a href="details_machined_parts.md#details-machined-parts"><img src="../images/machined_parts_1.jpg" width="200"></a>|<a href="details_tools.md#details-mechanical-tools-and-consumables"><img src="../images/tools_1.jpg" width="200"></a>|<a href="../../../electronics/details/details_components.md#details-electronic-components-and-tools"><img src="../../../electronics/images/components_tools_1.jpg" width="200"></a>|

---
## More Information
[Open Dynamic Robot Initiative - Webpage](https://open-dynamic-robot-initiative.github.io)  
[Open Dynamic Robot Initiative - YouTube Channel](https://www.youtube.com/channel/UCx32JW2oIrax47Gjq8zNI-w)   
[Open Dynamic Robot Initiative - Forum](https://odri.discourse.group/categories)  
[Open Dynamic Robot Initiative - Paper](https://arxiv.org/pdf/1910.00093.pdf)  
[Hardware Overview](../../../README.md#open-robot-actuator-hardware)  
[Software Overview](https://github.com/open-dynamic-robot-initiative/open-dynamic-robot-initiative.github.io/wiki)  
[Back to Actuator Module](../README.md)  
[Back to Top of Page](#details-center-pulley-preparation)

---
## Authors
Felix Grimminger

## License
BSD 3-Clause License

## Copyright
Copyright (c) 2019-2020, Max Planck Gesellschaft and New York University