Control scale of parts with parameter in assembly

[schiefer93]

Hey,

im having trouble to understand, why i cannot have a assembly with a parameter "scale" (as export-parameter) and then place multiple different parts in this assembly, which use sketches like 10mm*scale, while scale of the single parts are linked to the assembly. I want to change scale inside of the assembly from 1 to 2 and have all components in this assembly scaled by 2. Right now i would need to change the parameter in every part by hand, because of the error "circular reference".

How would you solve this task?

Thanks!

[kacper.suchomski]

Hi

I think it's possible with iLogic.

I'm not sure about your intentions though. I mean, I'm not saying it's a bad idea; it's just that many people here have asked about scale, not understanding the real implications of their ideas.

It would be nice to understand more details, but I think it's doable.

[schiefer93]

Thanks for the quick answer.

So i need to redesign a assembly regarding functionality, but at the same time it will be 3d printed from now on. So my target is to have a possibility to resize it later, in case the components dont fit.

I would like to start with like 2,5 times the current size, which i need to change anyway and same me some work later on by having this "global" resize-option.

[kacper.suchomski]

Creating such a global control system in itself requires additional work. It only starts to be profitable when you know that there will be more than 3 variants. With three, we are on the verge of rationality of building such a system in terms of the amount of work time invested. Are you sure it makes sense?

[schiefer93]

Well, as of now, i can't foresee the amount of additional work required. Like i remade a sketch and added "*scale" to the relevant dimensions. So thats work i would need to to nonetheless. Coming from other CAD-software i hoped it would be as easy as linking this part-specific parameter to a global one, which i control in the assembly. I dont know it would be done with iLogic, since i have not worked with it.

[kacper.suchomski]

Schematically it will look like you just described it. You only need to change the equations in the parameters and then creating logical rules to connect parameters between files is as much clicking as 2 changes (3 variants).

[kacper.suchomski · Accepted solution]

Look at this video:

[johnsonshiue]

Hi! This is doable. You don't need to scale the parameters or dimensions. You can scale the part bodies directly. Use Direct Edit -> Bodies -> Scale -> set the scale factor. The factor should be a model parameter. As Kacper mentioned earlier, this scale factor can be driven by an iLogic rule in an assembly.

Many thanks!

[SBix26]

Like @kacper.suchomski I believe this could be accomplished via iLogic.  But essentially you are asking Inventor to work backwards.  In Inventor, parts define the assembly, not the other way around.

I would approach this using the master modeling concept in which all (most) parts of the assembly are defined as separate solid bodies in a single part file.  If it's a more complex assembly, then multiple subassemblies defined by multiple master models, each of these including the most basic skeletal geometry and global parameters-- such as scale from a "super-master" model.

Then all parts are ultimately derived from master models, and master models are derived from the "super-master" model.  If everything is set up correctly, all you'd need to do is change the scale parameter in the "super-master" part, then update the assembly; voilà! — all parts and assemblies updated.

If you've got a reasonably small example that you can post, I'd be willing to show you how it might work.

---

Sam B

Inventor Pro 2025.1.1 | Windows 11 Home 23H2

[kacper.suchomski]

I would be careful about suggesting a scaling command (direct editing).
I mean, there are cases where it will work, but there are also a lot of scenarios where it will do more harm than good.

Unfortunately, the author of the post has not disclosed and specified his intentions so far, so our advice is just random.

Imagine a conveyor belt.

We want to change the length of the belt x2. Should we use the model scaling tools? No way. Rescaling the body, in addition to changing the length, will:

1. change the thickness of the belt on the bend (highlighter effect)
2. change the distance of the belt from the last rolls (along the conveyor)

Therefore, scaling projects should be approached very consciously.

[schiefer93]

Hey, many thanks, thats exactly what i was looking for!

[schiefer93]

Thanks for everyones answers!