Drawing Structure

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Improving the structure of Drawing Files:

This is a general discussion suitable for beginners.  The purpose is a broad understanding of the facilities provided by AutoCAD and how they may be used in the office.  Examples come from the field of architecture but the concepts apply to all disciplines.  If you wish to learn how to use the commands mentioned then you should refer to specific tutorials.

Introduction – a personal viewpoint:

Because of the wide variety of task complexities, staffing arrangements and skills it is not possible to make any specific recommendation as to the best methods other than the simpler the better.  While some may find Layers difficult to handle, Xrefs can be a veritable nightmare.   It is recommended that you have a look at the separate discussions on Layers and Xrefs.

There are many different approaches to the use of Paperspace, Layouts, Plot-files, Modelspace, Viewports, Layers, Inserts (Blocks), Attachments or Overlays (Xref) and all that but a good system will be flexible enough to take account of the scale and complexity of individual projects and the number and skills of the participants.  Often, however, “standard procedures” or the particular philosophy of the project CAD leader might overrule logic.

Insistence upon the use of ATTACHMENTs rather than INSERTs or “One drawing sheet per file” or “Plot files separate from the model files” are examples of rules that make good sense in one situation but which may be nonsensical in others.  The build-up of drawings from multiple Xrefs when the work is all within the scope of one person and the data is all particular to the one project may produce unnecessarily complicated editing procedures and file management in an otherwise simple situation.

AutoCAD allows models of any size to be built in a single file and also allows multiple drawing sheets to be assembled within the Paper space of the same file.  Thus provided the operator and available hardware can capably handle the amount of data why would one resort to the additional complexity and management task of Xrefs or separate plot files?   There are of course many good reasons related to sharing of the task of data production but logic suggests that the additional complication of Xrefs or separating plot-files from the model files should be added only when individual circumstances demand.

In the opinion of the author if there is to be a basic rule it should be “One project - one file” rather than “One drawing one file”.  If, however, production needs, scale of project, hardware limitations, plotting procedures, data sharing etc. demand then the data may be divided into separate files of plans, elevations, sections, details etc. Experienced CAD managers will be able to plan project file structures in advance but often it is more convenient to start with a single file and subdivide the data progressively as drawing and editing circumstances demand.  The permutations and combinations of project size and complexity, staff numbers and skills and project timeframe are so complex as to seem to defy a single solution. 

Organisation of drawing information:

Drawing file structures can be influenced by the size and complexity of the job and the number of and skill levels of available staff.   Drawing data can be classified and organised in many different ways such as building-zone (A wing, B wing etc.), drawing-type (general arrangement-plan, electrical plan etc.) view-point (plan, section, elevation etc.), scale (location, component, assembly etc.) allowing a project to be shared among several operators of varying CAD skills and building knowledge.    

The building information may be created all in one file that also includes all of the drawing sheets ready for plotting or the data may be distributed across multiple files and later combined in one or more files for plotting.  Multiple sheets for plotting may be organised in a single Layout or arranged one sheet per Layout.  A different arrangement is to have plot-files empty save for the outline of one or more sheets with contents attached from external reference files.

If using Xrefs the more complex the arrangement the more file-naming and organisational problems arise, but the trade-off is an enhanced ability to share the work. 

Plotting procedures can also influence the way data is arranged as some multi-plot functions require one sheet per file.

Data “ownership”:

Different data types tend to be “owned” by different operators (usually according to their skills).  For example one person may be responsible for setting out all of the general arrangement plans and sections while another is responsible for the elevations and another the details etc.  This provides a basis for task and file separation; particularly Xrefs.  It is possible that one person could manage all general arrangement base plans in one file while another uses that file as an Xref as a background for detailing the fit-out (joinery etc.) or projecting elevations. To have several operators randomly working on the same drawings, unless very well managed, has a high potential for error.