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Dealing with Drawings in Old Setup Standards

Part 3

Barrie Mathews

In Part 1 and Part 2 of this article, I outlined 2 fundamental differences that cause problems when you need to convert old drawings to new setup standards, defined some general rules to make things easier when you encounter non-conforming codes, and discussed some processes for dealing with problem drawings. I will now recommend the kind of cad system that enables effective solutions for overcoming the difficulties with non-conforming drawings and through the exchange of drawings, provide the synergy to establish true industry standards that will reduce the number of times you have to deal with problem drawings. Specifically, the objectives are:

How to best deal with the different kinds of coding systems and variations in the extent of classification used.

To foster development of a more uniform standard of practice among firms engaged in the same line of work, and be able to automate the conversion of drawings as much as possible where standards differ. Before achieving this true industry standard, we need to lay out the underlying assumptions (principles) that dictate it, and the reasons for these assumptions.

1. We must have a common understanding of what we mean by the word "standard". Is it a protocol to always be followed and endure for all time? I think not because when that is the case, you become locked into using antiquated methods and are unable to take advantage of new technology and improved ways of doing things. Rather, it is "A protocol found most useful and best by the majority of practicing professionals at the current time". In the building industry (AEC work) practicing professionals should include all the professionals who have a need to use the drawings, but may only include the people inside your own firm. So when we use the word "standard", it must be understood as "Current Operating Standard".

2. During Part 1 and Part 2 of this article, I drew considerable attention to whether you are the creator (sender) of drawings to be re-used by others, or you are only the re-user (receiver) of drawings. But given that operating standards have to be upgraded from time to time to accommodate new technology, then almost everyone is a creator of drawings to be re-used by others eventually. Unless the drawings are never to be re-used (and one ought not plan for or assume this), older drawings will always need to be upgraded to current operating standards sooner or later. So when we are determining cad standards, we should assume that we are the creator of drawings for re-use by others. That means you need to develop your classification to a somewhat greater degree than is currently the normal. As you will see later on, you will only need to use the full extent of your classification for your plotstyles.

3. Lineweights should not continue to be tied to color now that there is an independent lineweight property available. Only the creator of the drawing knows the degree of contrast needed to convey the designer's intent, and so the correct lineweights should be applied directly as objects are drawn. When necessary, lineweight settings can be changed or overridden by the object as I will explain later.

4. Don't assume that you will be creating layers for everything. A layer offers a variable that is convenient for changing lineweight, color, linetype, or plotstyle, but so does your linetype and your plotstyle. While many of your object codes may be synonymous with layers, it is not necessarily what you want in all cases, and it won't always be so in the future. In any event, the fact that other methods are even available means they will be used on occasion, and so you need a way to deal with those methods.

A. Defining your coding systems and classification

1. At the highest level, use the same denominator for ALL of your coding systems, rather than having some of the codes representing objects and some for plotting characteristics (e.g. lineweights and linetype patterns). This means you develop an object code independent from your layer code that classifies all of your design objects. It is your most elementary code which governs all. It defines all of your sub-systems and the definition of all cad properties, including layers. This primary code will be synonymous with your plotstyle code which is defined in your named plotstyle table (*STB). I'll explain more about the use of that later.

2. Each named object that you define has a standard plotstyle, color, lineweight, linetype, and layer. 

For example, the linetype code represents the object class depicted by the line. The linetype for a wall is "Wall-??" (not "Continuous"), a foundation footing is "Footing" (not "Hidden") and the linetype name for a grid line is "GridLine" (not "Phantom"). Use your linetype as a variable. For a footing to be demolished, you may need a linetype such as "DFooting" that has a pattern definition of "Dot2". When you need to convert the linetype, you can convert the "Wall" and "Footing" linetypes to something else which may or may not have the same pattern definition. You can't automate the conversion of "Continuous" or "Hidden" because such codes will have been used more than once and for all sorts of different applications. The sub-system for linetypes will be less encompassing that the overall object code. The linetype won't need to distinguish between proposed and existing work. That is distinguished by lineweight on paper and in the computer, by the default lineweights assigned to separate layers for proposed and existing objects. The defaults can be overridden (if needed) by the lineweight setting in the plotstyles for proposed and existing objects. The object code (and corresponding plotstyle name) has a classification for each variation, where the linetype code, color code, and the layer code can be classified to a lesser degree.

3. The color code represents your major object classes for easy visual recognition. Because lineweights are applied directly, color can be used more freely to represent your major object classes and it also helps you in other ways too. 

For example, if you are still using color dependent drawings, developing an object code for color will assist you in the transition to Named Plotstyles. Once you have used colors to represent objects, you can put your naming convention for plotstyles into practice using tools that apply named plotstyles according to color. The plotstyle can also be changed in the same manner during development of your system for named plotstyles. The object code for color will also allow you to change lineweights using tools that apply lineweights according to color. For example, when you are converting a contract drawing to an as-built drawing, the heavy lineweights of all the proposed objects need to be changed to existing objects with lighter lineweights. Where you have set color by object for objects on the same layer, the color code provides the means to associate the desired lineweights for objects on the same layer as well as the new layer lineweights.

4. The layer code primarily represents the object groups for display, where each of your object groups (or assemblies) will need various layer names. The layer names may or may not be classified in the same way, or to the same extent as your object code and your named plotstyles. The layer property defines a default plotstyle, color, lineweight, and linetype to a layer, but the defaults may or may not apply for all of the objects on that layer.

5. The object properties for plotstyle, color, lineweight, and linetype are used to override the default layer properties when variations are needed.

6. The linetype library (i.e. the linetype definition file) defines the linetype pattern to be used for each linetype.

7. The default plotting characteristics for each plotstyle are set to "By Object Property" in your standard plotstyle table. The objective here is that anyone re-using the drawing avoids having to use the designer's plotstyles to define the linetypes and lineweights to convey the designer's intent. It is important that you reserve your plotstyle definitions to be used as overrides when you are unable to automate conversion or you want to over-ride the original intent temporarily.

a) When objects on the same layer need different linetypes and lineweights, your object linetypes and lineweights will govern in the 1st instance rather than making it mandatory to have to change the plotstyle name.

b) For standard operation, retain your plotstyle definitions for overrides that you can use in special cases when needed. Your cad properties are set in the drawing so that the standards are familiar, you can draw and plot what you see, and others can plot the drawing without your plotstyle table. Use another table where,

(i) automated conversion is not possible for some objects, and

(ii) in the normal course of your work, you need special presentations with alternate lineweights and some color highlighting, When you need to change the output then you retain the ability to define settings that will override the settings in the drawing for some of the objects. Look ultimately, for named plotstyles to become your industry standard of classification for design objects, where you can set up special plotstyle tables for localized applications.

8. Use only 1 to 3 standard textstyles that are coded only by the font and the width factor, with all of the text heights set to zero. Having codes of this nature makes it possible to convert them and makes the textstyles easier to use in programs for automated text entry.

9. Use standard dimstyles coded only by its general application and the type of arrowhead used, with the scales (dimscale) and linear scale factors (dimlfac) set to 1.0. This simplifies the variety of dimstyles for conversion and makes the dimstyles easier to use in programs for automated dimensioning. For example, you need only one dimstyle with your standard arrowhead or tick mark for regular dimensioning, maybe one that displays alternate units, and one that displays tolerances. Define the dimvar settings in the drawing unit that you use most. Additional sets of the same standard can be created for different drawing units, but you should use the overrides for all the settings that vary with the insert, such as scale, extension line suppression, and the linear scale factor for insertions in paper space. Make some toggle buttons to turn the dimse1 var ON and OFF if you do not like using the command prompt. With the productivity tools available today, there is no need to have separate drawings for different drawing units and scales.

B. Maintaining the "Current Operating Standard" and automating conversions. 

Create synergy through the exchange of drawings that will foster greater uniformity and keep your standards up to date. 

When converting to new classifications that are MORE GENERIC, use a name that retains the more specific classification by adding a descriptor following the new generic name, and then automate the changes with a conversion utility. The "re-user" of the drawing can then consider adding a more specific category to their standard, or automate a further change to the generic name. 

When converting to a new classification that is MORE SPECIFIC, identify (flag) the code that differs in classification using the name of the most widely used equivalent with a prefix in front, and automate such changes with a conversion utility. In this way, the receiver of the drawing can make a decision on whether they need the more specific classification. If they do, they can easily select the desired objects from within the group of objects identified the flagged code (name) and change them to the new code manually, or automate a further change to some other name. 

To develop true industry standards and to maintain those standards to accommodate new technology you must be able to,

a) identify and communicate the differences on a day to day basis between other professionals in the your industry, and

b) be in a position to make informed decisions to modify and upgrade your operating standards. 

Because design objects don't vary in practice, the object code gives you a common denominator for mapping existing properties to new properties. Your use of linetype names and colors is changed from pattern codes and lineweight codes to variables with definitions that you can freely define to suit local requirements. The desired plotting characteristics are applied by loading your own linetype library and by using an alternate plotstyle table.

For your own standards, ensure that no color or linetype name is used to represent more than one major object class. Of 255 colors available, there are 24 major groups in the various hues, 2 sub-groups of 5 (one light and one dark) within each major group, 5 colors available in each sub-group, and 15 random colors that can be used as codes. Linetype names are unlimited. Either of these object coding systems can be converted to a pattern and lineweight code if that is desired. 

Object IDs will become incorporated internally in the software for the most consistent and major object classes the software is designed for. But at the application level, you will continue to need specialization to deal with interaction between multi-disciplines and other fine tuning. User defined coding systems for localized requirements are still needed as well. Billions of dollars are lost each month in terms of production, stress, and frustration from having to deal with non-conforming cad drawings. While it takes considerable planning to organize your cad resources in the best manner for your operation, the results well worth the investment. In my opinion, the benefits outweigh the investment tenfold, not only in terms of increased wealth for your own company, but for the economy in general. 

Originally published in S-MAN E-NEWS by Softco Engineering Systems. Re-published by permission.

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