I have seen a few threads over the years regarding creating a coil that follows a circular path (think of a slinky) rather than a straight line (the only option for the Coil feature). I wanted to see if I could create one myself, so I searched through the forum and on the wider web, but all of the solutions that I found were half-baked, inaccurate, or just too cumbersome.
I remember some years ago seeing an Inventor modeling challenge to create a coil whose axis of revolution traces a circle so that the coil returns to itself and creates one continuous solid. I’ll call it a toroidal helix (or is it a helical toroid?). With this vague memory floating around up there, I knew there was some way to get what I was after. So, I decided to give it a go to see what I could come up with. I think I tried about 8 different approaches before I settled on one that I could get behind.
The attached file is the one I finally came up with. I know there are other users out there who have wanted a way to model one of these beasts, so I have decided to post it here. Also, I just think it’s pretty cool.
I eventually tracked down the Inventor challenge that I thought I vaguely remembered. It is the September 2004 challenge found here:
http://teknigroup.com/worldcup/worldcupfiles.asp?offset=130
The solution offered is actually quite brilliant. It is simple, elegant, but unfortunately, not parametric in any form. The sinusoidal spline has to be manually repaired if you want change the number of revolutions of the coil. The one I have posted does not suffer this disadvantage as it is fully parametric (see the Engineer’s Notebook in the part).
This part is a complete toroid of a helix, which is really only valuable as a “gee whiz look at that purdy shape” sort of a thing. But, the approach I used is adaptable to make a helix that follows a semicircular path. There have been numerous posts over the years about how to do this. In fact, that particular task is even easier than what I went through to get the complete toroid.
Feel free to use this part in whatever way you want (it is IV2010). Enjoy!
-cwhetten