By Gus Petrikas
Some time ago I wrote a tutorial on how to make Adaptive Springs in Inventor. While adaptive springs are nice to look at, they don’t really behave realistically. They can’t be dynamically moved in the viewport and if they are a part of an assembly, they need to be suppressed, etc. etc.
So I decided that it would be very nice to have an actual dynamic, compressible and expandable spring that can be moved with a mouse, or driven by any object simply by clicking and dragging. With a bit of though, I managed to develop a simple spring "system" and here is how you can make one yourself:
1. Create a coil that is half a turn long (180°). (Make sure you are creating and drawing the sketch in the "Back View". It is important due to the way Inventor handles coils.)
2. Create a sketch on one of the endpoints, project both ends.
- Connect the endpoint centres with a line.
- Place a point on the midpoint of the line.
- Finish the sketch.
3. Create a 3 point plane, between the projected end centres and the midpoint of the coil.
4. Create another sketch on one of the endpoints and project the point you placed in the step 2.
- Project the two circles of the endpoints.
- Connect the centre of one circle with the edge of the other circle with a line.
- Draw the line from the point that was placed in the previous step and make it perpendicular to the new line.
- Rename the sketch and call it "Alignment".
5. Save and close the part.
6. Create an assembly and place at least 5 segments of the coil.
7. Ground one of the segments to use it as a base.
8. Start constraining the ends of the half-coils by using the "Insert" constraint.
9. Constrain the planes we created of the very top and the very bottom half-coil by using angular constraint with a 0° angle.
10. Constrain the planes of the half-coils that are not on the ends of spring and are on the same side. Use the angular constraint with a 0° angle. Using a 0° angle sets the planes parallel to each other.
11. Select the top and the bottom half-coils and make their "Alignment" sketches visible. Constrain the short vertical lines by using the "Mate" command.
12. Try out your spring!
Optional: Turn on contact sets to prevent overlapping.
Optional: Put all of the parts in a sub-assembly and make the sub-assembly "Flexible".
Now this tutorial might look big and scary, it only takes around 5 minutes to create a dynamic spring once you know how it works. Remember, practice makes perfect.
This what it looks like in the viewport:
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