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Dealing with Drawings in Old Setup Standards

Part 2

Barrie Mathews

Part 1 of this series outlined two fundamental differences that cause problems when you need to convert old drawings to new setup standards namely...

Two kinds of coding systems used, one that represents the design objects, and the other that represents plotting characteristics only.

Varying extent in classification.

It also defined "3 General Rules" to make things easier when you encounter non-conforming codes:

X. If you are normally a sender of drawings, then tend to use more specific classification, or more generic if you are mostly the receiver.

Y. The definition of a cad property that is used as a code has to be unique. Use colors and linetypes to represent objects and ensure that no color or linetype name is used to represent more than one major object class.

Z. Add a more specific classification as a suffix to a more generic name, or flag the name with a unique prefix so the receiver of the drawing can consider adding a more specific category to their standard.

This part answers three questions that will help you to determine processes for dealing with problem drawings, and offer some special solutions for changing symbol blocks, linetypes, colors, layers, plotstyles, textstyles, and dimstyles:

1. What is essentially IMPORTANT, and what can be LEFT as it is?
2. What kind of system should your company use?
3. Are the new codes going to be more SPECIFIC or more GENERIC?

Symbol Names

a) Important: Symbols always represent the objects that you deal with in your field of practice and they tell the reader of the plan what the design objects are. It is important that the old symbols are compatible with the new symbols that will be used. You must either have both shapes listed in the symbol legend, or change the existing symbol blocks to match the ones that will be used for new work.

b) Make the classification of your objects and the symbol block names you use conform to General Rule "X". If you are a sender of drawings, then use more specific classification, or more generic if you are the receiver.

c) If the new symbol blocks are more generic, consider Rule "Z". Add more specific symbols, or identify the symbol blocks with a unique prefixes to the generic names so that the receiver of the drawing can consider adding more specific symbols to their standard.

Solutions:

(i) Automate the conversion of the existing block names to the new block names. If a new symbol block is more specific, automate the change to the name of your most widely used equivalent and add a prefix to identify it for more specific changes. You will have to manually select which insertions need to be changed and then replace those insertions with the more specific symbol block.

(ii) Redefine the block definitions by importing the new symbol blocks into the drawing. If the new symbol blocks have attributes, accept them as blank fields when you import them. Although the block's attributes are associated with each block insertion, they are stored as separate entities in the drawing. The existing block's attributes will remain regardless of whether the new symbol blocks have attributes or not.

Linetype Names and Colors

a) Important: The linetype patterns and colors identify what lines are and if you are using color dependent drawings, the color's lineweight conveys the importance of what is drawn. It is important that you change the linetype names and the colors.

b) Preferably, you need linetype definitions for the major object classes AND for patterns. Similarly, color definitions are needed for the major object classes AND for lineweights, densities, and text heights. Make the classification of objects and the kind of color codes and linetype names you use, conform to both General Rule "X" and General Rule "Y". If you are a sender of drawings, then use more specific classification, or more generic if you are the receiver. Use colors and linetype names to represent objects and ensure that no color or linetype name is used for more than one object class.

c) If the new codes are more generic, consider Rule "Z". For linetypes, add a more specific linetype, or flag the name with a unique prefix so that the receiver of the drawing can consider adding more specific linetypes to their standard. For colors, add a more specific color code or flag the object with an unused color.

Solutions:

Automate the conversion of the existing linetype names and colors. If a new linetype code is more specific, automate the change to the linetype name of your most widely used equivalent and add a prefix to identify it for more specific changes. You will have to manually select which objects need to be changed to more specific names, and then make those changes manually. If a new color code is more specific, automate the change to an unused color to identify it for more specific changes, or use one of the tints in the same hue as your most widely used equivalent.

Named Plotstyles

a) Important: Named Plotstyles represent each of the objects that you deal with in your field of practice. The named plotstyle is a variable that defines the linetype, color, lineweight, and screening properties for named objects and conveys what lines are on the printed output. It is important that you change the plotstyle names.

b) Make the classification of your objects and the plotstyle names you use conform to General Rule "X".

c) If the new codes are more generic, consider Rule "Z".

Solutions:

Automate the conversion of the plotstyle names. If a new plotstyle code is more specific, automate the change to the plotstyle name of your most widely used equivalent and add a prefix to identify it for more specific changes. You will have to manually select which objects need to be changed to more specific names, and then make those changes manually.

Layer Names

Importance depends upon whether layer names are also being used to define specialty of cad properties. That is, additional layers are being used to represent the same object, but with a different linetype or lineweight.

a) Assuming you do not use additional layer names to the define specialty of cad properties, pre-existing layer names can be left as they are because they can be made to plot correctly, and you do not have to use these layers for new drawing work. Layers NEED ONLY (my emphasis) affect plotting in cases where you want some, but not all of the objects on a layer to be plotted.

b) Make the classification of your objects and the layer names you use conform to General Rule "X".

If you avoid using additional layers to define specialty of cad properties, your layers will only represent objects, and the difficulty associated with using 2 kinds of coding systems does not arise. If you use layers to represent cad properties as well as objects, the difficulty is immense. There will be an enormous amount of work converting to and from other systems.

In my opinion, trying to use layers to represent cad properties is not a sensible practice, and it will frustrate the evolution of universal standards for layer names.

c) If you need all of the pre-existing layers to conform to your standard and the new layer codes are more generic, consider General Rule "Z". Add a more specific classification as a suffix, or flag the name with a prefix.

Solutions:

Automate the conversion of the layer names. Unless you need to turn off only some of the objects, the difficulties associated with varying extents in the classification of objects need not arise. Pre-existing layer names that are more generically classified can be left as they are, while your new work is placed on your more specific layers.

If you are using additional layer names to the define specialty of cad properties and the new layer code is more specific, automate the change to the layer name of your most widely used equivalent and add a prefix to identify it for more specific changes. You will have to manually select which objects need to be changed to more specific layer names, and then make those changes manually.

Textstyle and Dimstyle Names

Importance of textstyles and dimstyles depends upon whether there are non-conforming fonts, width factors, tick marks or arrowheads, or non-conforming placement of text relative to a dimension line. The level of difficulty in converting them depends upon whether text height has been defined in the textstyle rather than by the text object, and whether different combinations of dimvar settings have been defined in the dimstyle instead of using the dim overrides.

a) With the exception of the need for conforming fonts, width factors, tick marks or arrowheads, and placement of text relative to a dimension line, the existing textstyles and dimstyles can be left as they are. As with layers, these styles need not be used for any new work.

b) It is not necessary for your standard textstyles and dimstyles to be defined for any purpose other than for different fonts, and one or two kinds of arrowhead. In most cases you need only 1 or 2 standards for textstyles and about 3 standards for dimstyles. If this practice is followed, the difficulty with different kinds of systems will not arise. Changes can either be automated or done manually during work in progress. However, you must be careful that existing objects are not updated for settings such as scale, linear scale factor, extension line suppression, or any other setting that is specific to each insertion.

If textstyles are defined for each of your text heights and drawing scales, and if the combinations of dimvar settings are defined in the dimstyle, the level of difficulty associated with automated conversion of textstyles and dimstyles is severe.
c) Varying extents of classification do not apply to textstyles and dimstyles except as referred to in b) above.

Solutions:

If textstyles are classified only for the font and the width factor, and the dimstyles are classified only for the textstyle and arrowhead used, you can simply import the new textstyles and dimstyles. Then, use a conversion utility to automate changes from the old textstyles and dimstyles to the new ones for each of the objects in the drawing.

If existing textstyles are defined for each text height and drawing scale and existing dimstyles are defined for combinations of dimvar settings that vary by the inserted object (such as dimscale and extension line suppression), the problems associated with ridding the drawing of the existing styles make it impractical to do so. In this case, you will need to:

(i) Import the new textstyles and dimstyles for new work and retain the existing textstyle and dimstyle names in the drawing.

(ii) Use a text change utility to change the fonts and the width factors in the existing textstyles. Manually redefine each of the existing dimstyles for the textstyle (by changing the dimtxsty dimvar), the arrowheads (by changing the dimblk, dimblk1, and dimblk2 dimvars), and placement of text relative to the dimension line (by changing the dimtad and dimtvp dimvars). You will not be able to rid the drawing of all of the old textstyle and dimstyle names.

Part 3 will summarize my views and recommendations on the kind of cad system you need to  enable effective solutions to deal with all of the issues in non-conforming drawings, and, by evolution, define true industry standards that will that will reduce the number of times you have to deal with problem drawings.

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

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