topic Re: Adjustable spring in Inventor Forum

Adjustable spring

DCA3000 — Fri, 29 Aug 2025 11:08:35 GMT

Is there a way to model a compression spring at its free length, say 20mm, and set it so that when you put it into an assembly between two other parts that are closer together than 20mm, it compresses to the necessary length?

I’m not talking about driven constraints to animate the spring compressing, the spring won’t be compressing and lengthening in this assembly, but will stay compressed.

I’ve done this in the past but set I up the spring as an iPart with lots of various lengths selectable when the spring is placed in the assembly, but I thought maybe there’s a better way.

Hopefully I’ve explained what I’m after! Can anyone help?

Thanks

Dave

Re: Adjustable spring

andrewiv — Fri, 29 Aug 2025 11:35:47 GMT

Since there is no flexibility in parts, I use a similar workflow as you. I just go one more step and put the iPart into the content center and have the compressed length as a user input when they place the spring. You could probably use model states as well, but that would require the predefined compression lengths or the file would have to be modified every time a new one is needed.

Re: Adjustable spring

dan_inv09 — Fri, 29 Aug 2025 13:15:35 GMT

It doesn't have to be animated for you to use adaptivity.

Do you need to use the same part in different assemblies or even different places in the same assembly an be different lengths?

(You could always just make copies of the file, but Murphy's Law would make sure that there is something else that can't roll up in your Parts List or something.)

Re: Adjustable spring

dan_inv09 — Fri, 29 Aug 2025 13:18:19 GMT

(What if you could model it as segments to make it a flexible assembly? ... I can just see it blowing up spectacularly!!)

Re: Adjustable spring

johnsonshiue — Fri, 29 Aug 2025 20:45:31 GMT

Hi Dave,

The closest thing I think is leveraging the adaptive workflow. Basically, you need to set up the spring in a way that the height (and pitch implicitly) can be varied (adapted to other component geometry). Before inserting the spring to an assembly, make a copy of the spring (in the copied part, go to Tools -> Doc Settings -> Modeling -> uncheck "Adaptively used in an assembly" option). Insert newly copied spring to the assembly and turn on Adaptivity. Constrain the part accordingly.

Many thanks!

Re: Adjustable spring

DCA3000 — Mon, 01 Sep 2025 06:52:39 GMT

Hi, yes, the same spring is used in a multitude of different assemblies, each with slightly varying compressed lengths.

Re: Adjustable spring

DCA3000 — Mon, 01 Sep 2025 07:00:34 GMT

That worked in terms of the spring adjusting its height between the 2 faces in the assembly, but when I went back to the spring component drawing, it had also been compressed to the length of the spring in the assembly. I don't really want that to happen, the .ipt should stay at the free length.

Re: Adjustable spring

johnsonshiue — Tue, 02 Sep 2025 21:24:20 GMT

Hi! In that case, you will need two copies of the spring part or the same part with two model states (Adaptive vs Non-Adaptive). The adaptive one is for the assembly and the other one (free) is for documentation purpose.

Many thanks!

Re: Adjustable spring

dan_inv09 — Tue, 02 Sep 2025 22:01:05 GMT

I was thinking that maybe there was a way to have the part be adaptive in a flexible sub assembly.

But I guess if you can have two separate states in a part and have one that allows adaptivity while the other is static that that will work.

Re: Adjustable spring

johnsonshiue — Wed, 03 Sep 2025 02:12:48 GMT

Hi! Adaptive and Flexible are mutually exclusive. When a subassembly becomes flexible (no geometry change allowed), it cannot be made adaptive (geometry change allowed), vice versa.

Many thanks!

Re: Adjustable spring

dan_inv09 — Wed, 03 Sep 2025 13:17:09 GMT

I was thinking that the part needed to be adaptive to allow it to change in the flexible sub assembly.

I had tried to make an assembly of segments but it won't move in a straight line:

Re: Adjustable spring

johnsonshiue — Wed, 03 Sep 2025 22:58:36 GMT

Hi Dan, This is a very clever way of solving the problem. It is more like building a chain as opposed to a coil. But I can see the difficulty of getting the desirable movement.

Many thanks!