Over the years I have written a couple of items about line weights, plotstyles and the like, and somewhere in the depths of YouTube there is a video tutorial too, with terrible sound. I continue to get so many questions about line weights and plot styles, especially for AutoCAD.
So, I thought it was about time I re-addressed the issue, updated everything and tried to give more of a complete overview of why line weights are important in architectural drawing and how to achieve this in AutoCAD.
Why do we use line weights in architectural drawings?
A line weight is the strength or thickness of a line, achieved by using a variety of pens with different nibs, or applying different pressures onto the paper.
Line weights are used in architectural drawings to demonstrate relationships between elements, create depth, scale, to create a hierarchy in the drawing and to add clarity to allow the viewer to better understand the drawing.
Not only do we use line weights in architectural sketching, we also use them in all stages of architectural drawing, both hand drawings and computer generated drawings. In the following post we will look at how to achieve different line weights when working in AutoCAD.
Plot Styles in AutoCAD
When it comes to creating technical drawings in AutoCAD, understanding line weights and plot styles is essential for producing professional-looking prints and digital copies. In this post, we will explain what line weights are, how they work in AutoCAD, and how to work with plot styles to achieve the desired line weight for your drawing.
Line weights are a way to differentiate between different parts of a drawing by varying the thickness of the lines. In AutoCAD, line weights are measured in millimetres, with a thicker line weight indicating a heavier or more prominent object. For example, you might use a thicker line weight for the outline of a building, and a thinner line weight for the interior walls.
Plot styles are a way to control how AutoCAD prints or exports your drawing, including line weights, colours, and other attributes. There are two types of plot styles in AutoCAD: named plot styles and colour-dependent plot styles.
What is the difference between ctb and stb plot styles?
Colour dependent plot styles or ctb tables are predefined styles that specify line weights and other attributes for each colour in your drawing. They are assigned to objects based on their colour, with each colour corresponding to a specific line weight or other attribute. For example, you might assign the colour “red” to a line weight of 0.50mm, and “green” to a line weight of 0.25mm.
Named plot styles or stb tables are based on the actual colours used in your drawing, rather than predefined styles. This means that each object can have its own line weight, colour, and other attributes, regardless of its assigned colour. Rather than assign a colour to a layer which will then print an intended thickness, the stb allows you to set up a number of different styles which can then be assigned to layers, or objects. In some ways this gives you more freedom with your plot styles. However, this method can be more complicated to set up and may result in inconsistencies between different objects. The stb style does not tend to be used as often as the ctb styles.
Whether to use ctb or stb will often come down to personal choice, or indeed your office standards of the company that you work for.
To work with plot styles, you can access the “Plot Style Manager” from the “Page Setup” or “Plot” dialog boxes. From there, you can create and edit named plot styles, assign them to objects or layers, and adjust their attributes.
Switching from a .stb drawing to a .ctb drawing
Using the command CONVERTPSTYLES will convert the drawing from stb to ctb. When you use the command you will be asked to select the plotstyle you would like to use.
How to work with plotstyles in AutoCAD
In this post, I am going to go through line weights and plot styles the way I was taught, which is using ctb plotstyles. Remember, this is not the only way to do things, but this is the way that I know and use and it works well for me. This is generally how all of the offices I have worked in use plot styles and set up their CAD drawings. It is up to you whether you choose to set your drawings up like this or you could explore the stb option.
Once you have a set of layers that you like to use (read our layering standards guide here) – you can then go about assigning colours to the layers. The colours will be used to differentiate between the lines, but also identify the line weight of each line.
When we come to print, we assign the “CTB Plot Style” which tells the printer what colour and thickness each colour should be printed. For example, all cyan lines will be printed at a thickness of 0.35 in black, but all grey lines may be printed at a thickness of 0.18 in grey. You get the idea.
I would generally advise you don’t use more than the basic colours number 1 – 10 for general drawing. It can get overly complicated if you assign hundreds of colours different line weights, it just isn’t necessary.
These are my standard colour to line weight set ups:
Note that the last colours are printed as seen, ie printed as the colour rather than printed in black – this option in the plotstyle menu is ‘use object colour’.
My line weights are on the light side, so you may want to adjust them to suit your needs.
I feel like the best way to really explain line weights and plot styles it to show you!
The following video uses the FIA CAD template to demonstrate some of the key points of using line weights in autoCAD.
All of this line weight information is basically leading us to printing our cad drawings out as we wish to see them. This is a daunting process for a new CAD user, and can equally be quite complicated for people that have a good understanding of AutoCAD. The following outline shows the process going from cad drawing to printed drawing.
- Make sure you have set up your layers so that your lines are allocated correctly
- Make sure your layer colours correspond to the plot style you are planning to use to print
- Create layouts in your paper space so that you can easily allocate and save plot style and print layout and use publish shortcuts for printing
- Plot using the Plot command or publish command depending on your set up.
I recommend using a standard template file that you use every time you start a new drawing. I use the FIA Standard CAD Template, which you can purchase from the shop – however if you are looking for a free option, you can always download my free layer template and adjust it according to your needs.
Using a few standard plot styles
I tend to have between two and three plotstyles that I choose from. The first is my main style, which includes a few colours for site boundaries, hatch etc. I then have a completely monochrome option for black and white printing. Finally, I sometimes use an additional plot style for M&E drawings which have more colours available for demonstrating different electrical and drainage information. Rather than adjusting your main one, it is best to have a couple that you can go between as you need.
In summary, line weights are essential in architectural drawings because they help organise information, convey depth, and enhance the aesthetics of the design. By using line weights effectively, architects and designers can create clear, easy-to-read drawings that effectively communicate the intended design.
Plot styles are essential tools for creating professional-looking technical drawings in AutoCAD. By understanding how they work and how to use them effectively, you can ensure that your drawings are easy to read and communicate the necessary information to others. Whether you’re a beginner or an experienced user, taking the time to master these tools will pay off in the quality of your work.