Plotters: all you need to know

A simple guide to purchasing the right plotter for your business

Computer plotters are a type of output device commonly used for computer-aided design (CAD) applications. They draw images on paper after receiving a command from a computer.
They are designed to print large, hardcopy vector creations such as architectural blueprints, construction and surveyor maps, engineering drawings, and items such as big posters and billboards for advertising agencies and print shops.
A plotter differs from a traditional printer in that it uses pens to create the pictures. By allowing a pen to move mechanically, plotters are able to draw continuous line art onto the surface of the paper, imitating the vector graphics drawn on a computer.
Although ideal for printing large line art graphics, plotters are not able to reproduce raster graphics (such as is created in Photoshop). For this reason, wide-format inkjet and laser printers have become more popular for printing items such as banners and billboards.

Types of plotters
There are two main types of plotters for printing: flatbed plotters and drum plotters.

Flatbed plotters
Flatbed plotters, also known as table plotters, use a system where the paper is fixed and spread in a flat sheet, and the plotter moves a pen up and down, and left and right to draw the required marks on the paper.
This type of plotter consists of two drawing arms, each with its own set of coloured-ink pens or pencils. The drawing arms move over the stationary sheet of material and produce the desired image.
Typically, the plot size is equal to the area of a bed the paper lies on. This may be anywhere in the region of 6m by 15m.
Flatbed plotters are often used in the design of cars, ships, aircrafts, buildings, highways and so on.
A flatbed plotter operates at a very slow speed when drawing or printing graphs, due to the movement of the mechanical pieces. A large, complicated design may take several hours to print.

Drum plotters
Drum plotters, or roller plotters, move the pen up and down, and the paper left and right by rotating a drum back and forth to reproduce the image.
As a result, drum plotters to have a footprint smaller than the final paper size. Drum plotters can use more than one pen, allowing different coloured lines to be drawn.
The ink pens are held by the robotic drawing arm that moves side to side as the roller, which holds the paper or material, moves back and forth. This results in the production of high quality graphics and imaging.
In this way, a perfect graph or map is created on the paper. Drum plotters are used to produce continuous output, such as seismographs of earthquake activity.

Cutting plotters
Another type of plotter is the cutting plotter. In a cutting plotter, the pen or pencil is replaced with a sharp blade. This allows the plotter to cut vinyl and other thin materials to produce graphics for signs, vehicles and advertising. The plotter may have a pressure control to adjust how hard the knife presses down into the material, allowing designs to be fully or partly cut out.
Cutting plotters are often relied upon for precision contour-cutting of graphics produced by wide-format inkjet printers – for example, to produce window or car graphics, or shaped stickers.
Vinyl sign cutters are used by professional poster and billboard sign-making businesses to produce weather-resistant signs, posters and billboards.
These are made with self-coloured adhesive-backed vinyl film that has a removable paper backing material.
The vinyl can also be applied to car bodies and windows for large, bright company branding. A similar process is used to cut tinted vinyl for automotive windows.
The collection of vinyl on hand will determine the colours that are available.
The vinyl is stored in large rolls to prevent creasing of the material.
Vinyl rolls are typically available in 38cm, 60cm, 91cm and 122cm widths.
Typically, only the upper surface with the vinyl is cut, but the backing surface is not completely cut through.
Completely loose pieces cut out of the backing material may fall out, resulting in a jam in the plotter roll feed or the cutter-head.
The vinyl knife is usually shaped like a plotter pen and is also mounted in ball-bearings so that the knife edge rotates to face the correct direction as the plotter head moves.
Smaller, desktop-size cutting plotters are available for the home market and are used for crafts and other hobbyist applications. Although cutting plotters are still widely used, laser cutters are starting to replace them as unit prices fall. Laser cutters are faster and can cut through a wider range of materials.

Did you know?
Sign cutters are primarily used to produce single-colour line art. Several colours can be cut separately and then overlaid, but the process quickly becomes labour-intensive for more than a couple of hues.
Sign cutting plotters are in decline in some applications, such as general billboard design, where wide-format inkjet printers that use solvent-based inks are employed to print directly onto a variety of materials.
It is becoming more common for large-format wide-carriage inkjet printers to be used to print onto heat-shrink plastic sheeting, which is then applied to cover a vehicle surface with the material and shrunk to fit using a heat gun, known as a vehicle wrap.

Using plotters

In order to use a plotter printer, users need to have CAD software on their computers.
Plotters essentially have two categories: technical plotters and graphic plotters. Both cater for different sections of the market and print in different ways.
Graphics plotters generally use more ink than a technical plotters – largely due to the fact that a higher-quality image is needed for graphics. Multi-colour plotters use different-coloured pens to draw their lines.

Large-format plotters use two different types of inks: pigment inks and dye inks.
Pigment inks are more often used on graphics plotters, but can also be used on technical plotters. Generally speaking, you generally won’t find a graphics plotter with a dye-based system.
Dye-based systems are used on technical plotters because there is not such a high level of quality required.
Some types of plotters use a combination of dye and pigment ink systems.

Plotters are able to work on large sheets of paper, from 0,6m and larger, while maintaining high-quality resolution.
In addition, a plotter may print on a wide variety of materials and thus offer the user many print options.
Materials that a plotter can print on include sheet steel, plywood, aluminium, plastic, cardboard and almost any flat sheet material.
Efficiency, reproducibility, accuracy and speed are all attributes of a plotter.
Patterns and templates can be saved on disk, which eliminates the hassle of having to load the same patterns or templates over and over again.
Additionally, the same pattern can be drawn thousands of time without any degradation.

Although plotters offer many advantages, you may have a difficult time finding the right location for your plotter. They take up more space than regular printers and require a large area for ease of access and use. Furthermore, the price of a plotter may be much higher than the price of printer.

Modern plotter technology
Pen plotters have slow speeds and complex mechanisms, and are only capable of printing line art. Advances in printing technologies have made them somewhat redundant. Inkjet technology has been touted as an ideal replacement. Such technology has a small, self-contained print head that moves across the paper, allowing manufacturers to produce wide format plotters that can print on large paper sizes. Microchip and memory advances enable plotters to perform more processing on-board, allowing for faster printing at high resolutions, with high levels of accuracy.
One big advantage of inkjet technology is the ability to print photo quality graphics, increasing the versatility of the plotter.

Plotter printer checklist

Ask yourself the following key questions before purchasing a plotter:

  • What size do you need to print?
  • What type of quality do you need?
  • What type of volume will the plotter be printing?
  • Is your choice suitable if the business grows?
  • Will you need networking capability?
  • Will your operating system support your printer?
  • Do you need inks that are UV-stabilised and waterproof?
  • What is your budget?
  • Do you need good reporting tools to analyse our print costs?
  • Would long-term rental be more affordable?
  • Will you be purchasing an extended warranty?
  • Will your plotter be well-suited to your particular industry?
  • Is there enough space available for the plotter to be properly used?
  • Will you pay someone for set-up and installation?
  • Have you assessed the ongoing running costs (cost per print and total cost of ownership) of your plotter?
  • Do you have adequate after-sales support?


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