How to create an advanced hole pattern with PTC Creo
… like the one on the Nest Smoke alarm
Recently the company Nest brought a smoke alarm onto the market: https://nest.com/smoke-co-alarm/life-with-nest-protect/
I find the look of it quite interesting, mainly because of the arrangement of the small holes that covers its surface.
Here’s how to create the pattern yourself with Creo (the technique should be transferable to other CAD software as well).
If it’s helpful to you, you can download the file I used to create this tutorial and have a closer look for yourself on how it’s done: https://www.dropbox.com/s/4qypowba2toecqy/pattern_nest.prt.1.zip
1. Prepare a surface/solid where you want to create the pattern.
I choose to create a round, thin and slightly curved solid with the revolve tool.
2. Start a sketch on a plane parallel to your surface.
In this case, the Datum plane front.
3. Draw sketch.
This is where it starts to get a bit tricky. You have to create a lot of circles with some important internal relations. Here’s what to do:
- Decide where the centre of you pattern is, and create 21 concentric circles with increasing diameter. Make sure to convert them to construction lines. Don’t worry about the exact diameter of the circles, as they’ll be constrained later on.
- Define a horizontal center line of your circles and two lines with the same center as the horizontal line, but tilted respectively 2 degrees up and 2 degrees down. Make sure these are construction lines as well.
- Start sketching the lower row of small circles on every second big circle. Their center has to be placed in the intersection of the big circles and the tilted line, and they have to be tangent to the horizontal line.
- Draw construction lines between the newly created circles, and make them have equal length.
- The every 2. big circle that you haven’t drawn any small circles on yet, has to pass through the center of the distance construction lines you created in step 4.
- Draw small circles with the centre in the intersection between the upper tilted line and the free big circles and make sure they are tangent to the horizontal line.
4. Extrude sketch.
Extrude the sketch through your surface/solid.
5. Pattern sketch.
Select your extrude feature and create an axis pattern with 45 instances distributed over 360 degrees.
Why 45?
The goal is to distribute the rows of circles equally over 360 degress. In the sketch in step 3 we defined that there’s 4 degrees in total between the centers of the rows. There are 2 rows in every instances and with the rotation of 4 degrees pr. row, it gives us a rotation of 8 degrees pr. instance.
360 degrees/8 degrees pr. instance= 45 instances.
6. Done.
Tadaa! If everything worked out correct, you should have something like the above.
Now that you have this as a starting point, you can adjust it to your own likings. Play around with the distances, the sizes, the amount of rows etc.
Please feel free to comment and ask if I didn’t explain every step thoroughly enough.
7. Shine it up!
I encourage you to take the model to your favourite render engine and, for the fun and practise of it, create a sleek rendering to impress your friends, mother or customers. The image below was created with KeyShot in just five minutes.
On a final note: Thanks to the PTC Community for helping me with this one. http://communities.ptc.com/thread/51698
