Creating duplicate parts, varying in size with absolute dimension

[Anonymous]

Hi, I am trying to make a mask. yes, sorry for adding one to the list. I have been trying to figure out a way to accommodate different sizes (scaling to %) while keeping key dimension/feature value as an absolute value regardless of the size.

Not too sure if iparts, ilogic, adaptive parts, or other methods would work. But I do prefer it to be more automatic, consistent & flexible(No to little errors when changing scale). Please help!

Goal:

To be able to scale(%) the part file while locking specific dimension of feature(s)

Things to keep in mind:

The mask is a shell with an organic shape, made from the scalp (create solid) --> scalp cut (from the same solid but scaled down)

The feature I would like to keep absolute throughout the sizes would consist of multiple work features.

THANKS, A BUNCH IN ADVANCE!!!

@Anonymous @johnsonshiue 

[Cris-Ideas]

Hi,

Scaling and keeping some dimensions does not really sound like scaling.

But in general, not being aware what exactly you are trying to achieve,  I would suggest as follows:

1) start from one end of the range (smallest/ largest) and build a portion of the shape you want actually to be scaled,

2) derive this shape with scaling factor,

3) build fixed size features on the top of that adaptively.

In theory this should work as long as fixed size features will fit for all scale range.

Key is NOT to change scalable geometry after it is derived. In such case everything starts to ...... rise problems.

Cris.

[johnsonshiue]

Hi! I believe this will depend on how the part is created. I guess you are building masks in different sizes (length, width, and depth). But, the thickness should stay the same.

Like Cris mentioned, for engineered parts, it is better to alter the model dimensions so you know what you are getting.

However, you mentioned that the shape is organic. As a result, the precise dimensions may not be relevant here. I guess you will need to use Direct Edit -> Body -> Scale or Derive -> Scale.

Either way should work. Direct Edit only deals with solid bodies, not surface bodies. Derive can scale body geometry and sketch geometry. I would think the main mask shape should be a surface body. Then it is thickened to the same thickness.

There are multiple ways to do it. Please share a non-proprietary example here. Forum experts can help take a look and provide further guidance.

Many thanks!

[Anonymous]

Thanks for the reply guys! @Cris-Ideas @johnsonshiue 

For more context:

1. I'm actually planning to make a feature for straps to tied to and I want to ensure that this feature will retain its dimensions. (Drawing to the side -->)
2. Attached is the STL of the base that I would like to scale

Yep, I have the solid base model already as attached and I am familiar with how to scale my parts. However, I am not sure how @Cris-Ideas method of using adaptive feature after scaling works. From what I understand; first scaling the base then building the feature after seems like it would require me to re-build the feature every time I scale, which is not what I am after.

I am looking to have 1 full-size model that I can easily replicate 'automatically' or let Inventor generate into various base sizes (scaled) while the feature above remains with the same dimension, location/placement on the mask across all sizes.

I don't mind spending time to define boundaries/numbers if it means I do not need to rebuild after every scaling.

I may have yet to dive deep into adaptive features, hence I may not know its full capabilities. If it actually is able to achieve my goal, I will be more than happy to learn from you. Thanks!!!

[Anonymous]

@Cris-Ideas 

Actually, can I ask why it's not good to re-scale something after it's been derived?

[Anonymous · Accepted solution]

@johnsonshiue @Cris-Ideas 

Actually, I kinda found a solution just tinkering around with iparts:

1. save the base file
2. open new part file and derive base (Set scaling to 'Scale=1')
3. build feature
4. Open Iparts > make scale the Key >Add rows and change scale
5. load from the table in the model tree

Not sure if this was what you guys meant by 'adaptive'. Would love to hear your thought and opinion on it.

Happy New Year BTW!

[SBix26 · Accepted solution]

A few ideas, one of which might work for you:

• iFeature for the strap mounting, which could be added after the scale derive, or after the direct edit.
• strap mounting as a separate solid body, which would only need to be moved after scaling main body by direct edit
• sketch block of strap mounting, similar to using an iFeature after the scaling operation

---

Sam B
Inventor Pro 2021.2 | Windows 10 Home 2004
LinkedIn

[Cris-Ideas · Accepted solution]

@Anonymous 

So I did not said that derived geometry should not be scaled.

But "NOT to change derived geometry after it was scaled"

The reason is that when you derive geometry new model is created and it has its own faces, edges and vertices. Structure of this model stays the same as long as geometry that you derived is not changed. Once you change geometry you are deriving your derived model changes and if there are any features build on the derived model in the part you are deriving it to, this features lost all references to the derived model as its structure changed.

So after you edit part you are deriving in to another part you need to redefine all features you had build on it.

This sounds probably little hard to follow, but in essence it is quite easy.

Following example is true:

1) you have a simple part A - cube

2) you derive part A to part B

3) you define hole in the derived cube constraining the hole to some edges and faces.

4) all is fine

5) you go and edit your cube by adding some extrusion

6) your hole in part B has lost its references and you need to redefine it.

So if you are building fixed size features on something you derive for your own benefit you should not change the geometry you are deriving.

Cris.

ps. For some reason once more I am not getting notifications from the forum, or more accurately I am getting random notifications, so please excuse late replays. Or perhaps someone from Autodesk could have a look what is happening with all my notifications.

[Anonymous]

Alright got it, thanks for the tip!