Coincident constraints becoming fixed constraints

[Kyle.Arnold]

Hello.

I'm having a problem with 3d sweeps not updating when a projected part moves. 

EXAMPLE:

I'm modeling cables running through a series of cable clamps.  I'm working in an assembly with my structure as one part, clamps as seperate parts, and cables as seperate parts.  I modeled the clamps first and am using them to create my 3d spline to run the sweep.  The clamps have moved several times and each time, the sweeps (cables) do not update to follow the new clamping path.  I have tried multiple ways of solving this.

I've tried to redo the splines using "Include Geometry" and running the spline through the centers of the clamps. 

I've also deleted the constraints (which for some reason turn into fixed) and reapplied them as coincident constraints. However, once I setup these coincidences, they always change back to fixed.

In a last ditch method, I've created 2d sketches at EVERY clamping location (yes that's alot of sketches, time and effort) and projected the circular geometry to get a center point.  This has seemed to work, but is so much work, there's no way we could use it regularly.

Has anyone encountered this before or know how I can improve/fix this method? 

I guess a better question would be, why does projected geometry update, but included geometry stay fixed?

Thanks!

Kyle A.

Inventor 2014

Dell Precision T3600

Windows 7

Xeon E5-1660 3.3 GHz

32 GB RAM

Nvidia Quadro 2000

[cwhetten]

Hi and welcome to the forum!

You have discovered one of the frustrating bits of Inventor.  I don't know why included goemetry in a 3D sketch can not be adaptive when projected geometry in a 2D sketch can.

It sounds like you have discovered the workaround using 2D sketches.  This usually works for me, but my use of adaptive 3D sweeps is only occasional, and usually quite simple.  It sounds like you have a more serious and complex need for this.

Have you looked into the routed systems modules for Inventor?  There is a tube & pipe module that has tools to automatically route pipe and hose, while maintaining adaptive links to other components.  I have used the hose routing tools with great success.  There is also the cable & harness module, which is similar but for electrical routing (I don't use the cable & harness module, so I'm not sure to what extent it compares to the tube & pipe module).  One (or both) of these tools may be just what you need.

Cameron Whetten
Inventor 2014

[mrattray]

It should be mentioned that Tube & Pipe and Cable & Harness only ship with Inventor Professional.

[rdyson]

Are you sure? 2013 Amateur had them, but may have been part of the suite and not stand alone

[mrattray]

I think you caught me in a fib.

[Kyle.Arnold]

Thank you all for your input. 

I tried a while back to get the firm to go for Inventor Professional just for the tube and cable capability, however they told me to use what I had since we're just breaking into using 3d and Inventor was already included in the suite we had.  Now may be the time to do a full on time/cost analysis, to back up my statements about tube and cable could save us money.

It is, however, pretty strange that when you "Include Geometry" in 3d sketches, the geometry included is not  adaptive.  I would think that would be the main reason for including that geometry... so that cables, braces, or whatever you model will update in relation to that geometry's location?  I thought that was the whole reason behind Inventor? Adaptive 3d Modeling?

[cwhetten]

Just for the benefit of others who might read this thread, I have attached a simple assembly that demonstrates the issue being discussed.  It is two tubes routed between some "fittings".  The adaptive tube parts were created in place in the assembly, each with a different method.

The one that doesn't work (the magenta tube) was created by including geometry from the fittings directly into the 3D sketch for the sweep path.  As the OP mentioned, the included geometry, rather than coming in as projected geometry, comes in as ordinary sketch geometry with fix constraints.  As such, the 3D sweep path does not update if the yellow fittings are moved.

The one that works (the blue tube) uses 2D sketches to project the geometry from the fittings (I created the sketches by starting the 2D sketch command and picking on faces of the fittings in the assembly.  This process automatically creates an adaptive sketch and work plane.  I then project one of the circular edges of the fitting to get a center point).  This geometry is adaptively linked to the original fittings in the context of the assembly.  Then, a 3D sketch sweep path is created by constraining a spline to the projected center points of the 2D sketches.  If the yellow fittings are moved in the assembly, the 3D sweep path updates to follow.

The attached files are version 2014.

Cameron Whetten
Inventor 2014