Assembly Drawing Methods

Scott,

We have been an Allegro user for more than 15 years and initially we used to export our data to AutoCad to do the drawings. We concluded long ago that it was much more practical to maintain the drawings in the .brd file. It allows us maintain a much higher degree of continuity between the actual data and the drawing. There have always been sychronization issues when you have the data in two places, so we have tried to avoid this wherever possible.

We use color files to maintain the views/layer mapping to each of the drawings (Fab and Assembly) and their respective sheets.

So as an example, if you have a 2 sheet Fab drawing and the drawing number is 12345, we would have a color file called 12345-1 for sheet 1 and 12345-2 for sheet 2. If you had a 3 sheet assembly drawing numbered 12346, we would have a color file for each of those sheets 12346-1...12346-3. We also have the revision embedded in the names to allow for different revs of the same drawings.

The color files allow each user to do the drawings with whatever subclass(es) they choose (we do have recommended standard layers), but other users can quickly pickup the design and navigate to the appropiate drawing using the visibility form.

Hope this helps.

We generate our assembly drawings inside the Allegro database. We do not create a separate board file by importing IPF files or export DXF from the board into AutoCAD or Visio. As you said, doing things the Export/Import way you take the risk of the assembly drawing data becoming out of date. I have Allegro symbols of different size formats that can be placed in the Allegro database and quick update to the title block then you are in business.

I have been doing this way for a very long time and the only issue that seems to come up is the ability to scale up the assembly view (2 to 1, 4 to 1) so it can be read on a printout. This has become less of an issue as when we started to store these drawings electronically in PDF format instead of killing trees.

As far as importing the assembly data into a 3rd party drafting tool, I have done this as well but it is much easier keeping things in one database then maintaining two.

Mike Catrambone
UTStarcom, Inc.

FWIW, on the scaling issue, we have created 1/4 and 1/2 scale formats that, when plotted at full scale, will produce 4/1 and 2/1 drawings.

Another way to get around the scaling issue is to create Details of the features/classes that you want to be on your drawings. You can scale up/down the details as neccesary as well as mirror for the bottom side. In our case we have automated most of the drawing creation/display process entirely within Allegro. Our Allegro library contains custom format drawings for the border and title blocks. When there is a need to show a more complex 3d assemby view, we import DXF from ProE and add it to it's own assembly sheet within Allegro. Our final drawing export from Allegro to manufactuing is a single PDF that contains all the sheets. I definitely recommend keeping the assembly & lamination drawing creation process within Allegro.

Randy

Creating a Detail of the features/sub-classes will work but that information can get out of date but with a script like you have it may not matter because it is automatically updated. We used the multiple scaled format symbol options, as Charlie outlined, a while back but the format seemed to take more space then the actually assembly view. It is more important to have a assembly view that can be read vs. having it on a pretty format.

We went to the simple title block, that we used for our artwork layers , for the Assembly and Fabrication drawings to get the largest view possible. We still generate 3D Pro-E Assembly drawings for the higher level assembly of the mechanical components which includes some of the major components but a basic 2D Assembly drawing out of Allegro showing the parts placement works just fine for visual inspection. Using PDF files of these drawings is definitely the way to go.