#  Make actuator body 

 



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**Note:** Your document units should be in the MMGS system! If they aren't, change your settings by going to **Options,** selecting the **Document Properties** tab, and clicking on **Units** in the side menu.

## Draw base shape

\[[Video: Make actuator body](http://www.youtube.com/watch?v=FA4mqUkRKqA)\]

   ![image7_1](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/2024-11/image7_1.png?itok=fQqJzmjW) 

 

In the top plane, draw a 12.7mm diameter circle, centered at the origin.

   ![image8_2](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/2024-11/image8_2.png?itok=SYNrUHIH) 

 

Draw a line across the diameter of the circle.

   ![image8_trim_clarify](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/2024-11/image8_trim_clarify.png?itok=byZt-IAY) 

 

Use the **Trim** tool to remove half of the circle’s perimeter, leaving a semicircle.

   ![image9_1](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/2024-11/image9_1.png?itok=5HaY5Er2) 

 

We manually offset the bottom by drawing 3 lines to connect the arc endpoints, keeping everything at right angles.





## Offset for actuator wall thickness

Now give the actuator 2mm wall thickness.

First, use **Offset Entities** to offset the sketch arc by 2mm. Make sure the “Select chain” option is unchecked so that the flat bottom is not offset.

 ![image10_2](/sites/g/files/omnuum4601/files/2024-11/image10_2.png)

 

   ![image 11](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/2024-11/image11_crop.png?itok=S09yjjp7) 

 

We manually offset the bottom by drawing 3 lines to connect the arc endpoints, keeping everything at right angles.

   ![image12_1](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/2024-11/image12_1.png?itok=lzqW2mfU) 

 

Use **Smart Dimension** to make the bottom 2mm thick as well.

   ![image 13](/sites/g/files/omnuum4601/files/styles/hwp_1_1__960x960_scale/public/2024-11/image13_0.png?itok=ENFlGT1I) 

 

Use Smart Dimension to make the bottom 2mm thick as well.

## Extrude

Exit the sketch, and **Extrude** the shape 170 mm.

 ![image14  extrude clarify](/sites/g/files/omnuum4601/files/2024-11/image14_extrude_clarify.png)

 

 ![image14_0](/sites/g/files/omnuum4601/files/2024-11/image14_0.png)

 

 ![image3_1](/sites/g/files/omnuum4601/files/2024-11/image3_1.png)

 

## Fillet

\[[Video: Fillet edges](http://www.youtube.com/watch?v=ALIxYCswmO0)\]

Add a 1.1 mm radius **Fillet** on the two long edges of the actuator’s flat face.

 ![image15 fillet clarify](/sites/g/files/omnuum4601/files/2024-11/image15_fillet_clarify.png)

 

 ![image15_0](/sites/g/files/omnuum4601/files/2024-11/image15_0.png)

 

 ![image16_0](/sites/g/files/omnuum4601/files/2025-05/image16_0.png)

 



 

##  Bibliography 

Galloway et al. (2013) [Mechanically programmable bend radius for fiber-reinforced soft actuators](/publications/mechanically-programmable-bend-radius-fiber-reinforced-soft-actuators).

Maeder-York et al. (2014) [Biologically Inspired Soft Robot for Thumb Rehabilitation](/publications/biologically-inspired-soft-robot-thumb-rehabilitation).

Connolly et al. (2015) [Mechanical Programming of Soft Actuators by Varying Fiber Angle](/publications/mechanical-programming-soft-actuators-varying-fiber-angle)

Connolly et al. (2016) [Automatic Design of Fiber-Reinforced Soft Actuators for Trajectory Matching](/publications/automatic-design-fiber-reinforced-soft-actuators-trajectory-matching)



 

##  Contributors 

Panagiotis Polygerinos

Kevin Galloway

Zheng Wang

Fionnuala Connolly

Johannes T B Overvelde

Harrison Young