Best Practices for Typography in Technical CAD Drawings

Technical CAD drawings are the main communication tool between designers and stakeholders like clients, manufacturers, and customers. Given this importance, draftspersons take great care to ensure that the drawings are visually pleasing. This care is clearly evident in choices related to typography, line thickness, spacing, and many other aspects. After all, these elements greatly influence how the parties perceive the quality of work, attention to detail, and ability to produce drawings of high standards. 

While geometric elements clearly affect a drawing’s appearance, typography’s role in aesthetics is often overlooked. So, why not join us as we discuss typography in technical drawings (font types and the popular fonts), the best practices for font usage in drawings, the criteria for choosing the best CAD fonts, and the importance of fonts in CAD drawings? 

Typography in Technical Drawings

The Merriam Webster dictionary defines typography as the appearance, arrangement, or style of alphanumeric characters and symbols (collectively known as type). By definition, therefore, typography entails arranging type in a way that makes it visually appealing and legible and, based on the chosen style, helps readers interpret information in CAD drawings. 

Today, there are thousands of fonts, with some better suited for use in CAD drawings than others. The suitability of the best CAD fonts is tied to the four main aspects of typography:

1. Font style: There are several font styles, including Serif, Sans-Serif, Script, and Decorative
2. Font color
3. Font size
4. Font structure: This aspect relates to characteristics such as single- or double-stroke fonts.

The best CAD fonts are Sans-Serif, meaning they do not have extending features at the end of the stroke (called Serifs). They feature a single stroke, scale well when you zoom in or out, and are legible.

Font Types

There are four main categories of fonts:

1. TrueType fonts
2. Shape file fonts
3. PostScript fonts
4. OpenType fonts

TrueType Fonts (TTF)

Designed by Apple and widely adopted by other companies, including Microsoft in their operating systems, TrueType fonts are known to guarantee the highest quality possible on printers and computer screens. Some examples of TTFsinclude Helvetica, Times, Arial, Century Gothic, and more. 

Shape File Fonts (SHX)

Autodesk developed the Shape File font during the formative years of CAD in the 1980s, when computers lacked the power to process advanced graphics. The company designed it as a simpler font that featured few lines, and could, therefore, display faster on slow computers. 

As a result, Shape File fonts cannot accurately represent curved letters like O or Q. The letters instead have a boxy design as shown in the image below. Some examples of Shape File fonts include Simplex, txt, Monotxt, Romanc, Romand, Romans, and Romant, just to mention a few. 

Letter Q as Defined by the Original Shape File Font (source)

PostScript Font

Adobe developed PostScript fonts as scalable fonts that could be printed and/or displayed on a computer screen. There are two types of PostScript fonts: Type 1 fonts, which use a simple command language, and Type 3 fonts, which use the PostScript language to form complicated designs. Some examples of PostScript fonts include Numbus Mono, Palladio, URW, Antique Olive, Garamond, and more. 

AutoCAD does not directly support the Type 1 PostScript font. The font must first compile into a shape file before the software can use it. BricsCAD and Revit do not support PostScript fonts. 

OpenType Fonts (OTF)

OpenType fonts use a font technology that combines PostScript Type 1 and TrueType fonts into a single format. Microsoft developed the OTF and introduced it in 1996. AutoCAD and BricsCAD do not support the OpenType fonts. Revit works with OTFs that use TrueType outlines.

Common Fonts Used in Technical Drawings

Designers and draftspersons prefer a few fonts, some of which are the default fonts in certain CAD software. These common fonts can thus be considered the best CAD fonts. They include:

1. Arial
2. Simplex
3. txt

Why Fonts Matter in Technical Drawings

In marketing, web, and app design, fonts play a symbolic and functional role. Many scholars and observers have written articles and research papers on the make-or-break nature of the decision to go with a particular font over another. And the reasons are quite extensive, ranging from fonts’ ability to evoke emotion, capture and direct attention, and enable companies to create a brand identity to their role in facilitating a better user experience. These reasons are better described by the term ‘font psychology.’

And just as fonts matter to companies and brands, so too do they matter in technical drawings. For instance, fonts help companies create a unique identity. Similarly, fonts can help people identify drawings from a particular design firm. This is especially true if the firm is known to use a specific font. Of course, other factors, such as those captured in the firm’s in-house CAD standards manual, may also help create an identity. 

Generally, fonts matter in technical drawings because they:

1. Influence identity
2. Contribute to the aesthetics of the CAD drawings
3. Help users interpret the information contained in the drawings
4. Direct attention to a particular section of the drawing, particularly based on the font color

Best Practices for Font Usage in Drawings

The following best practices can guide designers, engineers, architects, and draftspersons on how to use fonts in technical CAD drawings:

1. Use unambiguous numbers, letters, and symbols regardless of whether they are slanted or vertical.
2. Avoid using different font styles in the same CAD drawing.
3. Ensure legibility of the fonts. For instance, if you use slanted lettering, make sure that the slope to the right from the horizontal is at 75°, according to ISO 3098-1:2015 standard. This angle ensures the text remains legible.
4. Avoid using single stroke characters that feature decorations and serifs. For instance, use ‘Z’ instead of ‘Z’ or ‘Z’.
5. Do not underline the lettering because this affects legibility. If the text has to be underlined, the ISO 3098-1:2015 standard recommends that you interrupt the underlining in places where the lower-case letter has a tail, as in the letters g, p, q, and y.
6. Ensure adequate spacing around each character.
7. Use capital letters instead of lower-case letters because the former are easier to read if the size of the CAD drawing is reduced. Only use lower-case letters in cases where they are part of abbreviations, codes, or symbols. The ASME Y14.2 standard specifically requires designers to use upper-case letters unless lower-case letters are required.
8. Use fonts whose strokes have a consistent density.
9. Choose fonts that do not touch spacing lines in instances where information is to be tabulated.

Criteria for Choosing the Right Font

Legibility

A common thread through most of the best practices listed above is the emphasis on legibility. Legibility enhances the readability of notes and title blocks, enabling the recipients of the drawings to understand the information therein. 

Designers and draftspersons should avoid fonts that are illegible at first glance, forcing users to scrutinize the drawings further to discern the letters and numbers used. Not only do such fonts fail to convey the information clearly, but they also lead to time wastage as the users attempt to make sense of the notes. In addition, they should ensure adequate spacing, use upper-case letters, avoid underlining the letters, and use the recommended slope (for slanted letters).

Consistency

It is always a good idea to limit the number of fonts you use in your CAD drawing. Using too many fonts, even high-quality ones, can reduce the clarity of your drawing. In fact, even using several fonts from the best CAD fonts catalogue is somewhat disastrous because these fonts will make your drawing appear crowded. This, in turn, affects the next criterion: aesthetics.

Aesthetics

As we stated earlier, draftspersons strive to ensure their drawings are pleasing to the eye. And the typography does indeed make or break the appearance of a drawing. It is, therefore, advisable to choose and use fonts that accentuate the drawing’s appeal.

Scaling

Scaling is another criterion to consider when choosing a font for your technical CAD drawings. IThe best CAD fonts remain legible when zoomed in or out. At the same time, and given that there are instances that require you to use lower-case letters, it is good practice to use a font whose lower-case letters are still legible when you zoom out.

Compliance with Font Standards

CAD standards and regulatory standards guide practices in the world of CAD. CAD standards, in particular, are quite a number and touch on the different aspects of CAD, including fonts/lettering, layer management, file organization and management, version control, dimensioning, and more. 

On the font front, there are two main standards, the ISO 3098 and ASME Y14.2, that specify the requirements for lettering and fonts. In most cases, the best CAD fonts comply with the requirements set forth in these standards. The two main standards are:

1. ISO 3098 Standard

The ISO 3098 standard outlines the requirements for lettering that designers and draftspersons should use in technical drawings. It guides the application of lettering using drafting systems, such as CAD software, CNC systems, freehand lettering, templates, and dry transfer systems. 

The ISO 3098 consists of six parts, with the first part (ISO 3098-1:2015) specifying the general requirements. ISO 3098-2, the second part, specifies the Latin numerals, alphabets, and symbols for use in technical drawings. The third part, ISO 3098-3, specifies the use of Greek alphabets as symbols in technical drawings.

The British Standards Institution (BSI) has adopted this ISO standard, christening it the BS EN ISO 3098.

2. ASME Y14.2 Standard

The American Society of Mechanical Engineers (ASME) came up with the ASME Y14.2 standard. The Y14.2 standard, titled Line Conventions and Lettering, establishes best practices for, among others, the best CAD fonts. 

It notes that lettering, a term that encompasses both numbers and letters, should be well spaced, opaque, and single-stroke gothic. It permits either vertical or slanted lettering and specifies the minimum letter heights for various drawing sizes. The ASME Y14.2 specifies letter spacing and legibility requirements.

Customization and Font Management in CAD Software

AutoCAD, BricsCAD, SolidWorks, and numerous other CAD software products allow you to change the default font style. You can even install new fonts. It is worth pointing out that while most of these CAD software programs allow you to customize and manage fonts, they usually do so by letting you choose only the fonts installed in the operating system. 

This means that if you want to add a new custom font, you must install it on your computer or operating system. AutoCAD lets you install fonts within its interface, while Revit requires installation via the operating system. Nonetheless, you can customize the font, i.e., change the font styles by opening the requisite dialog box. 

You can access AutoCAD’s Text Style dialog box by clicking the Text Style icon in the Annotation ribbon panel within the Home ribbon tab. BricsCAD’s Text Style Explorer dialog box lets you change the default font as well as the font or orientation of the existing style. To access this dialog box, use the STYLE command or click Tools and choose the Text Styles option from the Drawing Explorer menu. ArchiCAD’s Test Style panel lets you change the font type, font height, alignment, text format (bold, italic, underline, and strikethrough), and font script.

Conclusion

Many players in the marketing world recognize the role of typography. Incidentally, the benefits that fonts confer to marketers are the same as what CAD designers experience when they use the best CAD fonts. Fonts help establish a company’s unique identity. Furthermore, fonts convey information, make drawings more appealing, and draw attention to particular sections of the drawings. Of course, the choice of the font matters; factors such as compliance with lettering standards, consistency, aesthetics, scaling, and legibility influence this choice. (For context, the best CAD fonts have the Sans-Serif structure, are single stroke, scale appropriately, and are legible.) And to help you choose the right font for your CAD needs, we have listed nine best practices. Refer back to them regularly for guidance.