Inserting vendor models

I'm working on a model of a spray box that uses various pnuematic cylinders to move things. This is a sort of learn on the go project, as I did take a course in Inventor awhile ago, but haven't had much of a chance to actually use it.

My first question is when selecting a vendors 3d model (from their web site), what would be the preferred extension to use? Many of them don't seem to have the Inventor .iam extension, usually .sat or some other form.

The second question is, are such vendor drawings, like cylinders, usually supplied so as to be 'live' and fully constrained? By that I mean once the file is downloaded, I should be able to insert it into my assembly, and move the cylinder rod in and out, without any obvious errors such as pulling the rod completely out?

The one I just downloaded for example, seemed to only give me the option of showing the rod in one particular position. While I can open the .sat file and reconstrain it, should it not be already? Or am I just expecting too much?

Or am I just expecting too much?

Neutral CAD file formats such as STEP, IGES, .... are referred to as Base solids or often as "Dumb" solids as there are no constraints between parts or in parts.

I would look for in order of preference:

1. Native filetypes (ipt, iam) not as common as vendors typically want their parts to be used in any CAD system.

2. STEP (*.stp) universal format will open in most CAD programs (except AutoCAD)

3. Native SolidWorks or Pro/E

3. Granite or Parasolid

4. ACIS (*.sat) v7 or earlier (Hoops ACIS Viewer needed to create later ACIS version files to v7 to open in Autodesk products).

5. IGES (*.igs) format

http://www.myvbooks.com/ac55jsp/stores/1/ML205-1P_Working_with_Neutral_P309C98.jsp

Extra work is often/usually needed when working with neutral format files.