Why are constraints deactivated in Assembly?

[Vagulus]

I have a model which, in part, involves a pipe inserted between former rollers. My plan was to constrain the pipe to each of the rollers with a concentric constraint. With the IAM file loaded I go to the Sketch Tab and find that the Constrain Panel is deactivated - greyed out. Why cannot I constrain objects within my assembly?

[-niels-]

In an assembly you are not constraining sketches, so you're looking in the wrong location.
To constrain parts together you need to look on the 'assemble' tab, there you'll find several options for assembling:
Constraints, Joints and the assemble command.

Please check the help files on how they're used.
I think from your description you'll want to use an insert constrain.

[Vagulus]

Hi Niels

I should have known that .  I plead insanity - I am just returning to Inventor after a year using Solidworks at College.  My mind is seriously befuddled.

This is the sort of setup involved:

I don't think I have to explain the concept that you push the upper roller down and crank the handle which should result in a bend in the pipe.   My idea is to make the pipe "stick" to each of the rollers so that I can make some measurements of the geometry as the process proceeds.  I would have thought that a Tangent Constraint would be the option

I have tried it.  It seems to work okay when I stick the pipe to the Former Roller (the top one) but it seems that there really is no constraint effect because sticking the pipe to the right-hand Idler Roller makes a heck of a mess.

The original constraint - pipe to Former Roller - gets ignored.

[JDMather]

1. In your image you have the wrong Tangent solution selected. 

2. Assembly constaints are the same in any MCAD program.

3. Attach your assembly here if you can't figure it out.

[Vagulus]

Hi JD

If I use the alternative Tangent Solution I get a really weird tangency.

If I use the one I showed in the previous post I get a better concentricity

but it lacks alignment

In short, I get funny results every which way but loose. 

I created a workplane on the pitch circle of the Former Roller groove, and and constrained the centreline of the pipe to it.  That got the alignment sorted out.  Things were a bit better but I could not control whether the pipe sat above or below the axle.  Constraining the pipe to an Idler Roller sent the whole thing Crazy.  I'm really confused. 

My assembly file is attached and you should be able to download the full set from

https://onedrive.live.com/redir?resid=CAD78704467531B3!185&authkey=!ADTiiOoRfEW5k54&ithint=file%2czi...

This was my first effort as a project, and as such it is pretty much a self-taught hackers dogs breakfast.  Sorry, but I think I'd do a bit better these days

[Frank-Oosterwaal · Accepted solution]

Hi,

If it was up to me I would avoid tangent constraints for this.

I've downloaded your set and after a few virus scans the company allowed me to open your files

First thing I noticed is that your assemblies are not aligned to the origin.

Might want to do so in the future, it saves allot of trouble (probably best to redo your jack assembly)

There are a couple of ways to get your pipe to align with the press.

In the screencast I show you one way to get it to work.

Hopefully it helps getting you in the right direction.

[Vagulus]

You wrote:

First thing I noticed is that your assemblies are not aligned to the origin.

Might want to do so in the future, it saves allot of trouble (probably best to redo your jack assembly)

That's what I meant about the files being a bit of a dog's breakfast.

Thanks for that.  I see what you are doing.  I would never have thought of that one.