Update 6/24/09: Alibre wants to keep Design Xpress secret, and has removed several of the pages linked to below

Update 8/7/09: Alibre has removed STEP file import from Design Xpress, so it’s no longer useful as a STEP file viewer.  (OK, you can import STEP files during the first 30 days, but after that, you’ll have to pay or find something else).  Go here for or my latest MCAD news posts.

Alibre Design Xpress is the free version of Alibre Design.  It is significantly less capable than Alibre Design Standard.  Limitation include only 5 unique parts per assembly, no advanced modeling tools, and no advanced drawing functions.  Alibre has a feature comparision here.  However, Xpress can still do a lot, including create assemblies (many free versions can’t), import and export files in various formats [import DXF, DWG; export STL], be used professionally, and create 3D PDFs.

With the free version of any proprietary software, the terms can change at any time.  My Design Xpress license allows 25 5 [changed when updated to V11] unique parts per assembly.  Until recently, the normal Xpress limit was 10 unique parts; now it is 5.

In any case, Design Xpress makes a fine STEP file viewer [for 30 days].   You can drag and drop STEP files onto the Xpress Control Panel (but not a part or assembly window), or use the Import menu or button.  This brings up the Import dialog box, which controls how the STEP file is imported.

Alibre 11 STEP file import options

STEP files don’t always import correctly, so it’s good to have these options available.  Note that these options do affect how quickly the part is imported.

I tested Alibre using the same Norcomp HD26M part; it imported without a problem.   I rotated, panned, and zoomed the part without problems.  Since I often end up with the part at weird angles, I appreciate the View–>Orient–>To Plane… menu which snaps the part view back to a plane.

I found measuring a little tricky at first, mostly because what I thought I was selecting wasn’t what I really was.  I was viewing the part looking straight at the front; when I rotated the part a bit (as shown in the picture below), I easily selected the features I wanted.

The Linear/Pairs measurement options takes the first mouse clicks after you select it; I could not figure out how to reset the points being measured without closing and re-opening the measure dialog.  So I had to be careful where I clicked the first two times.

HD26M STEP model in Alibre Design Express

I’ve noticed that Adobe’s Acrobat 3D PDF files are becoming common.  For example, I’ve seen 3D PDF models at Tyco Electronics and Norcomp.

The best about Acrobat 3D?  Since it’s been built-in to Acrobat Reader since, IIRC, 7.07, all you need to do is click on the link, and (assuming your browser has Acrobat setup correctly) the model appears in your browser.  If you click on this link to a Norcomp 180-026-103 HD26M connector Acrobat 3D model, you should see similar to this:

HD26M connector shown by Acrobat Reader 9

The 3D PDF format still isn’t a replacement for STEP or IGES files.  The biggest issue for mechanical designers is that, as far as I know, you cannot import 3D PDF parts into a MCAD program and use them in an assembly.

Another problem is that it’s not always possible to measure 3D PDF models.  Suppose I want to know some distances that are not documented on Norcomp’s 180-026-103 2D PDF drawing.   I cannot measure using Adobe Reader 9 and Norcomp’s model, since Norcomp did not enable analysis when they created the model.  If I have Acrobat Professional 7 or later, then I can measure (and can enable measuring for Acrobat Reader by enabling analysis and saving the modified PDF).

When the 180-026-103 model has measuring enabled, Adobe Reader 9 can measure like this (click for a larger image):

Measuring HD26M with Acrobat Reader 9

I found it a little hard at first to get Reader 9 to measure what I wanted, but it did get easier with practice.

Another problem is that measurements are in “model units”.  For the 180-026-103 model, the model units appear to be inches, but I know that because I know how big a HD26M connector should be.

So right now 3D PDF is an interesting technology, especially for documentation, but I’ll be downloading STEP files for my designs.