#  Step 1: Rough Design 

 



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#### Begin creating the part

- Start by creating a new model file in NX. (File → New: Choose Model/Modelling).
- Then, make a new sketch drawn in the XZ-plane (Insert → New Sketch: choose XZ-plane with your mouse).
- Draw two lines 25 mm in length, starting at the origin. The angle between the lines should be 40°. These lines will help to align the channels in later steps.
- Lastly, click on “Finish Sketch” located in the bottom toolbar.

   ![cda-step1-1-0.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-1-0.png?itok=mjUTKp4o) 

 

[Click here for larger image](/file_url/465)

#### Design the combustion chamber.

- Insert a revolved part (Insert → Design Feature → Revolve).
- Click on the “Sketch Selection” item in the new “Revolve” menu. A new sketch should appear. Choose the XZ-plane again.
- Now sketch two circles (Insert → Curve → Circle) with origin (0,0) and diameters of 50 mm and 56 mm, respectively.
- To go back to the "Revolve" menu, click on "Finish Sketch" again (the button is in the upper left corner now).

   ![cda-step1-2.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-2.png?itok=ZnqZlnzJ) 

 

[Click here for larger image](/file_url/466)

- Then choose the vector to be the Z-vector (should be blue) and the point to be the point of origin.
- The angle should start from 0° until an angle of 360°.
- Finalize by clicking on OK.

   ![cda-step1-3.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-3.png?itok=oODslXcn) 

 

[Click here for larger image](/file_url/467)

#### Add channels

- Hide the hollow sphere by right-clicking on the “Revolve (2)” item in the part navigator (left panel). Choose “Hide” and the sphere is now hidden.
- Insert an “Extrude” part (Insert → Design Feature → Extrude).
- Click on “Sketch Selection” item in the “Extrude” menu. A new window (“Create Sketch”) will open. In the type section, choose "On Path".
- Then choose the sketch-line at 40° drawn before. Set "Arc Length" to 0 mm and click "OK". The view will now turn.
- Draw another circle with origin (0,0) and a diameter of 12 mm.
- Click on “Finish Sketch” after you are done.

   ![cda-step1-4.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-4.png?itok=6ouxpJHx) 

 

[Click here for larger image](/file_url/468)

- Choose a specific vector. In our case, it is the "Face/Plane Normal".
- Set start and end distance to 0 and 40 mm, respectively.
- Finalize by clicking "OK".

   ![cda-step1-5.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-5.png?itok=AoMdsW-j) 

 

[Click here for larger image](/file_url/469)

- To create the middle channel, repeat the steps used to create the first channel.
- This time, choose the guide line perpendicular to the sphere.

   ![cda-step1-6.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-6.png?itok=niGQefRv) 

 

[Click here for larger image](/file_url/470)

- To make the left channel, we can just create a mirrored copy of the right channel.
- Copy the geometry (Insert → Associate Copy → Instance Geometry).
- Click on Select Object and then choose the cylinder at 40°.
- Specify the vector to be the Z vector (vertical axis) and the point to be the point of origin.
- Set the "Angle" to 180° and the "Number of Copies" to 1.
- Finalize by clicking on "OK".

   ![cda-step1-7.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-7.png?itok=Z96UHDHs) 

 

[Click here for larger image](/file_url/471)

#### Add horizontal cylinder

- Add another "Extrude"-part.
- Choose the ZY-plane for the sketch.
- Now sketch a circle with an origin of (0,28) and a diameter of 25 mm.
- Finish the sketch to return to the "Extrude" menu again.
- In the "Limit" section choose "Symmetric Value" and enter 50 mm.
- Finalize by clicking “OK” again.

   ![cda-step1-8.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-8.png?itok=lYfwPWuW) 

 

[Click here for larger image](/file_url/472)

#### Unite

- Unite all parts (Insert → Combine → Unite).
- Select all parts and finalize by clicking "OK".

   ![cda-step1-9.png](/sites/g/files/omnuum4601/files/styles/hwp_1_1__720x720_scale/public/sorotoolkit/files/cda-step1-9.png?itok=2F07HERL) 

 

[Click here for larger image](/file_url/473)

### Bibliography

Loepfe et al. (2015) [Contrast Agent Incorporation into Silicone Enables Real‐Time Flow‐Structure Analysis of Mammalian Vein‐Inspired Soft Pumps](/publications/contrast-agent-incorporation-silicone-enables-real-time-flow-structure).

Loepfe et al. (2015) [An Untethered, Jumping Roly-Poly Soft Robot Driven by Combustion.](/publications/untethered-jumping-roly-poly-soft-robot-driven-combustion)

Loepfe et al. (2014) [Design, Performance and Reinforcement of Bearing-Free Soft Silicone Combustion-Driven Pumps.](/publications/design-performance-and-reinforcement-bearing-free-soft-silicone-combustion)

Schumacher et al. (2014) [3D printed lost-wax casted soft silicone monoblocks enable heart-inspired pumping by internal combustion.](/publications/3d-printed-lost-wax-casted-soft-silicone-monoblocks-enable-heart-inspired)

Shepard et al. (2013) [Using Explosions to Power a Soft Robot.](/publications/using-explosions-power-soft-robot)

Stergiopulos et al. (2014) [A Soft Combustion-Driven Pump For Soft Robots.](/publications/soft-combustion-driven-pump-soft-robots)

### Contributors

Michael Loepfe