Having trouble achieving IDs and ODs of a design

[buenavea]

Hey Autodesk Community, 

Please see attached picture - I am having trouble designing a double funnel, where I need to maintain some ID and OD measurements. Its OD1 that is my issue, I have no idea how to shrink the OD down to 12.7 without decreasing the 1.2 mm. If you have any suggestions for how I can fix this or design pointers, let me know! 

Thank you so much. 

[NigelHay]

Something like the attached? Otherwise, I don't see how it is possible.

[buenavea]

I am assuming that you are using the most recent version of Inventor? I am using ver. 2021, so I am getting this pop-up 

I don't suppose you know a way to convert this file so its openable on my version? 

[NigelHay]

All I can do is save as a .stp file. It will show the shape but nothing else.

[JDMather]

@buenavea 

Your first sketch in not making use of obvious symmetry about the Origin.

Your first sketch is not fully defined and missing some dimensions while duplicating other dimensions.

Your second sketch is not fully defined.

Your third sketch is not fully defined.

If I take this on - are you interested in learning how to model this correctly in Inventor?

(It will require starting over from scratch.)

[buenavea]

@NigelHayI see what you did - did you model the long barrel part as a separate part or did you just fix the sketch to make it into one? 

[buenavea]

Hi Jeffrey, thanks for your notes. Would the resulting design differ from what Nigel is proposing up above? I.e would the barrel remain straight instead of having different diameters throughout? 

[JDMather · Accepted solution]

@buenavea 

If you follow my instructions we will model the geometry correctly.

It might take some back and forth questions as I don't think you really really know what you want just yet.

Start a new file.

Create the sketch as shown above.

Note the position of the Origin.

Attach your progress here. (I don't expect you to get it first time, but let's see how this goes.)

[buenavea]

@JDMather is there a certain order you need to constrain your dimensions? I am at the part where I need to create the outer funnel, but every time I try to constrain the 1.2 mm distance between the funnels and the OD of the outer funnel, it switches the two around so that the 12.7 mm is the ID and the 13.9 mm (12.7+1.2mm) is the OD. I tried switching the order of constraining including adding in that 0.6 mm thickness, but it always tells me that one or two of the values will be over constrained once I add it in. 

[JDMather]

@buenavea 

No new file Attached?

[Frederick_Law]

OD1 = 12.7

OD2 = 11.5

OD1 - OD2 = 1.2

1.2/2 = 0.6

And you say OD1 should be 0.6 thick?  And ID for OD1 is 11.5?

You sure?

[NigelHay]

I just modified your sketch. This was to show a possible solution, I don't think it is achievable without creating a step in the tube.

[JDMather]

@buenavea 

Did you figure this out?