Before looking at the different size of plotters available in the market let us see the standard size of the plotter available, these sizes show the maximum size paper that can be used in them.
The actual plotter size may be a little bigger then the paper size that can be used on these plotters.
Some common paper size and the name used for these sizes are given in the next table.
For business applications such as plotting of graph for the business presentation, etc., the A size plotter provides very good quality output.
For architectural or engineering application one would require a minimum D or E size plotter.
Types Of Plotters
Plotters can be divided into different types based on the number of pen divided into different types based on the way pen and paper movement takes place, it can also divided into different types based on the printing method used by the plotter.
Cost and different capability of the plotter such as number of colors, maximum paper size, printing speed etc. very much depend on the type of the plotter.
Single Pen & Multiple Pen Plotters
Plotter are available as single pen plotter and multiple pen plotter, it is not differentiated as single color and multiple color plotter, as on can get multiple color image using a single pen plotter as well.
Although the multiple pen plotter are better than the single pen plotters, the cost advantage of single pen plotters keep it alive in the market.
If you have a single pen plotter you can plot multiple colors by makiing the plotter pause after drawing all the image of one color and allow you to substitute the pen with a new color pen.
This method is quite frustrating if you are require to frequently change the pen, for example, when printing on overhead transparencies.
If most of the time your requirement is multicolor printing then it is better to go for a multi pen plotter, which will automatically change the pen, whenever required. Into a single-pen plotter
In a single-pen plotter, you manually insert the pen into a pen holder. In a multiple-pen plotter, you load the pens into the pen-changing assembly and the main pen holder.
Pen holder
Pen holder holds the pen that is drawing and collects different pens as they are needed. Main pen holder acts on the instructions supplied by the computer.
On some plotters, the pen are placed in a circular arrangement that is called a carousel, on others, the pen are placed in a straight line arrangement.
Once image of one color is drawn, the pen is put back at the pen-changing assembly and a new color pen is taken by the plotting mechanism.
Most of the drawing software that require plotters for output, such as the CAD software have inbuilt optimization method where they print all of the one color image first then go for the second color pen and draw all the image with the second color, this save the plotter from frequently changing the pen.
Some plotter in the market are available as single pen unit which can later on be upgraded to multiple pen model.
This is a good option if you want to start with single pen plotter and later on want have the facility to use multiple pen.
Smaller plotters have more requirements for the multiple pen then bigger plotters because most of the small plotters are used to draw business presentation which requires multiple colors, whereas most the bigger plotters are used to draw architectural and engineering drawing where single color output is more common.
Advantage of Multiple Pen Plotter
Multiple pen plotters have one big advantage over the single pen plotters that one can automate the complete plotting process using these plotters.
Once all the required color pens are loaded into the plotters and the paper is provided, the user need to only give the command to plot the required image.
The plotter will complete the entire plot without any assistance from the user.
Same process with a single pen plotter may require a number of pen change by the user, user will need to sit and keep watch waiting for the pen replacement.
Drawback of Multiple Pen Plotter
The advantage of the multiple pen is also disadvantage, as one need to keep all the pen ready with ink filled and exposed nib. This makes the chance of pen tip drying a very common problem.
If one uses an ink that does not dry fast enough, to save to tip from drying, then the image on the paper may get smeared when the pen makes multiple move over the printed image.
One needs an ink that must dry quickly enough on the media so that lines are not subsequently smeared by the pen tip, yet the ink should not dry on the tip when the pen is waiting to be used.
To reduce this problem of ink drying on the pen tip, one can buy plotters which will have option to cap the pen when the pen is sitting in the pen-changing assembly. this cap will be automatically removed when the pen holder takes the pen for drawing.
Flatbed and Drum Plotters
Based on the way pen and pen interact on a plotter the plotter can be divided into two types.
- Flatbed and
- Drum Plotter
On the Flatbed plotter as the name suggests the paper lies on a flat bed i.e. a flat surface and the pen is moved on this paper to produce the required image, on the drum type plotter the paper is hold on a drum like construction and both paper and pen are moved to plot the required image.
Flatbed Plotter
As shown in the Figure, flatbed plotters are flat rectangle shaped surface. These plotters are made bigger then the largest size paper that they can accommodate.
The extra space is required for plotting mechanism to move around.
On this flat surface a pen is moved left, right , up and down to plot any requited image. On a flatbed plotter and the pen is moved.
As the paper does not move, one can produce image with very high accuracy on these plotters. This mechanical movement produces very high accuracy than 0.001 inch).
The fixing of the paper provided another advantage with these plotters i.e. one can plot image of maximum size limited to the plotter size but one can plot image of any minimum size required by the user, which is not possible on drum plotters, the drum plotters have some fixed minimum size where one can not only plot any image smaller than that.
These flatbed plotters are more suited in smaller sizes of A and B size, on bigger size the space requirement to keep them makes it unsuitable, for higher size drum plotters are better option.
The flatbed plotters plots the image as given in the figure. As shown in this figure, to plot any image the pen holder moves in the horizontal position from left to right and according to the image to be drawn the pen moves vertically up or down.
The pen will touch the paper to draw the image or lift up from the paper where no drawing is required.
This vertical and horizontal movement can be used to plot any image on the paper.
Drum Plotter
On a drum plotter the paper and pen both are moved on plot the required image.
drum plotter is placed between a drum and a platen and this drum-platen assembly bolds and moves the paper up and down vertically, meanwhile the pen is moved left an right horizontally.
This vertical motion of paper and horizontal motion of the pen together is used to plot any required shape on the paper.
The accuracy of the drum plotter is also to the accuracy of the flatbed (better than 0.001 inch), but as the paper is moved up and down multiple times during the plotting process the effective accuracy is less then the flatbed plotters.
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