Tangent assembly constraint: ellipse surface to line

[kwilson_design]

Why can't Inventor constrain an ellipsoidal contour with a line? We have pressure cylinders which uses a 2:1 ellipse. These cylinder get welded to a base stand fixture. The surface of the ellipse nestles in between contact points of the base stand, in this case lines of geometry. Yet Inventor can't constrain them as such. Any ideas for a good workflow (at the assembly level) so that we don't have to ground components and use the Analyze Interference tool to make sure we are right on the surfaces? I don't understand why it will work for a cylindrical surface but not an elliptical surface.

[JDMather]

Can you attach example assembly here?

(I assume you use the same parts in multiple assemblies and multi-body solids are not an option?)

[kwilson_design]

Yes these parts are used in multiple assemblies and multibody solids would not work with our BOM structure. Basically our cylinders are made up of bottoms, formed sidewalls, domes and a threaded collar. All of those are individual parts of a welded assembly. That assembly then goes to another assembly where the cylinder is welded to brackets, axles, base stands, etc. The cylinder sits inside of the base stand in this case.

I've attached some simple geometry part and assembly files. I'm trying to get the elliptical surface of "cylinder.ipt" to sit on the edge of the two "bar.ipt" files. You'll see once you open it up.

[rdyson]

A rather involved work around. Probably more stable that a tangent constraint though.

[JDMather]

I can think of some more complex solutions that invovle Copy Object geometry from one part into another - but perhaps the solution is easier.

Something has to be fixed in space - I'll assume you know the position of the bars.

Add the components to Contact Sets, drag the tank down till it hits the bars and ground.

This is quick and easy, but of course doesn't allow for parametric changes.  But if it is all you need.....

(might do this as a sub-assembly)

[kwilson_design]

rdyson,

Yea I definitely don't want to add work features to parts. Trying to keep this at the assembly level and use the tolls there. Thanks for your input though.

JD,

Contact Sets are great and offer a much faster and far more precise method of determining where these components come in contact. Thanks for the reminder in them as I have totally dismissed using the contact solver lol.

Granted, I'd love for Autodesk to add the ability to select an elliptical surface to more than just planar surfaces. I don't understand why it never has been. We come into this issue quite a bit. Unfortunately that portion of our assembly designs is not parametric, so it's always an involved task of moving components once the design has changed on an affected part. Perhaps I'll add it to the IdeaStation to see if others run into this scenario.

[rdyson]

I don't understand people's reluctance to add work features to parts, but everyone to his own.
Note that my solution is parametric and the work plane spacing can easily be linked to the spacing of the bars.

[kwilson_design]

With all due respect you answered your own question. It is a much more involved workflow. Not to mention it clutters the browser with features that are used upstream rather than for the part environment itself. Then there's always the issue with users forgetting to turn off the visibility of their work features and then you place those components into your assembly. Even more clutter, so I have to use the hot keys to turn off the visibility, adding time to the workflow. Add in that we are on a vault environment so its not an easy process checking out files to turn those features off. I could go on about why I think its a bad idea to have a workflow like that when in reality, all you are creating them for is upstream use in this case. Wouldn't it just make more sense to increase assembly constraint capabilities?