Hello everyone. I made a coil in Inventor and I am having trouble constraining it onto a screw. The screw needs to be in the center of the coil. I am really stumped on this one and any advise would be greatly appreciated!



Have you tried using a Tangent constraint?

I would, but the spring does not touch the screw. The spring’s diameter is about 1/3 larger than the screw. That is why I am having troubles. Thanks for your reply though. :slight_smile:


It’s been a while since I’ve used inventor, I’ve been busy learning solidworks in college this year… Could you make a work axis in the coil part drawing and then constrain the screw to the work axis?

I think that’s your only real option… I think a tangent constraint will just horribly confuse inventor, since the coil would have to be tangent at several points…

You can add an offset to the Tangent constraint. Figure out how far the spring needs to be away from the screw to be properly centered and then use that as the offset. The offset should be in a box in the lower left side of the Tangent dialogue box. The default is 0, but you can change it to other values. I’ve found this method to be quite helpful in developing constraints that will allow rods to slide in holes that are a little too big for them.

But I’ve had trouble using a Tangent with a swept surface so I don’t know if it will work for a helix. You also may have to try both an inside and an outside tangent (the two buttons on the lower right of the dialogue box). I can see a good arguement for using either one. It helps if you have the constraints set to preview, so you can see what you’re going to get before you are committed.

Kevin’s method may work as well. I’ve never played with helixes in Inventor so I’m not sure just how they pickup constraints. The thing about CAD systems is that they never quite work just exactly as you want them to all the time. So you are constantly having to learn “work arounds”, most of which you wind up figuring out yourself. Then as soon as you start to know how to do everything you need to do, they roll versions or change you over to a new system and you have to start over again :rolleyes: So keep trying until you make it behave.


Every cad package I’ve seen has problems constraining helix(s). I hate to say this, but if nothing already mentioned works, you may be best off just eyeballing it.

What are you trying to do? There may be an easier and more efficient way of doing it, expecially if it’s a cosmetic detail.


All I can say is try to use a work plane, or axis, although I havnt really had much experiance with the coil option in inventor, I’ve only modeled springs 3-4 times, and I havnt had to do much constraining.