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How to draw straight lines with a rule

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use a ruler to draw straight lines. Some rules are called straightedges Drawing a perfectly straight line freehand is very difficult. The long straight edges of rules can be used as a guide to draw straight lines, as long as the rule is in good condition and the edge is straight. A rule can also be used in this way with a cutting tool, to aid with cutting or scoring straight lines in a material.

For more information see: How to cut straight lines with a safety rule

Before you begin

If the ruler you use to draw a straight line isn't long enough your line might not be straight Make sure the rule you are using is long enough to cover the distance you need to draw. If you have to reposition the rule rather than making a continuous line, the line might not be completely straight.
To draw an accurate straight line it's best to use a sharp pencil The line you draw will probably be slightly displaced from the very edge of the rule. How much will depend on the thickness of the rule, the drawing implement and the position the drawing implement is held in against the edge of the rule.

To get the most accurate line, the drawing implement should have a thin point or nib which is held at a steady angle against the edge of the rule as it draws the line.

Ruler are3 commonly used to guide a pen or pencil to draw straight lines If you are drawing with ink, the line can be smudged by the rule touching the surface you’re drawing on. To prevent this, a rule with a bevelled edge can be turned upside down. This means the edge of the rule is raised slightly from the surface, which can make it more difficult to be accurate.

How to draw a single straight line with a rule

You might want to mark where you want the straight line to go before you draw it

Step 1 – Mark where to draw

If the line needs to be in a specific place or a certain distance long you might want to measure and mark where it is going. For example, if you wanted to draw a line for a margin on the left-hand side of a page you would measure the distance you want it to be from the edge of the paper.

You might want to measure and mark out the exact position for your line before you position the ruler To make sure the line is parallel to the paper’s side, you can measure the same distance at the top and bottom of the sheet. Mark these measurements and then draw a line joining these marks. If the marks are measured correctly, the line should be parallel from the edge.
Angle the pencil so the nib is close to the edge of the ruler to draw straight lines

Step 2 – Position rule

Place the rule in the position you want the line to be drawn. Hold the rule in the centre of where the line is going, as this should prevent the rule moving as you draw. Try to keep your fingers away from the edge you’re drawing. If you draw over your finger there will be a finger shaped bump in your line.

Using a rule can help you draw a perfect straight line

Step 3 – Draw line

Ensure the rule is in the correct place, hold it steady with one hand and use it to guide the drawing implement. Make sure the point or nib stays at the same angle against the edge of the rule. If the position changes while drawing the line won’t be straight.

How to draw parallel straight lines with a rule

A rule is a simple measuring device, rolling rulers can be used to draw parallel lines Rolling rules are specifically designed to easily draw parallel straight lines. The roller in the body of a rolling rule means it can be moved up and down while remaining parallel to its original position. Folding rules can also be folded in such a way that two straight edges are perpendicular to each other. This allows one edge to work as a guide for keeping the other edge parallel to its original position.

For more information see: What are the different types of rule?and What is a folding rule?

If there is a hook on the end of a rule it can be used to keep the edge of the ruler parallel as it's moved up and down a surface Standard rules can also be used to draw parallel lines, although you may need to take a little more care to ensure they are completely parallel to each other. Some rules have a hook or buttress on the end, which can be used to keep the rule in a parallel position to the edge of a surface.
Mark where you want the parallel lines to go

Step 1 – Mark where to draw

To draw lines that are parallel to each other it’s advisable to mark out where the lines will go before you draw them. Use the rule to measure the distance apart you want the lines to go. Mark down one side of the paper, or whatever you’re drawing the lines on to, the position you want each line to start.

Measure and mark where you want the parallel lines to be drawn To help the lines remain parallel the same distances should be marked on the other side, where the lines will end, with one or two other measured marks being placed where the lines will run through. As long as the measurements are accurate and consistent you’ll be able to use them to correctly position the rule to draw parallel lines.
Angle the pencil so the nib is close to the edge of the ruler to draw straight lines

Step 2 – Position rule

Line the rule up with the measured points and hold the rule in the centre, as this should make the rule less likely to move. Try to keep your fingers away from the edge you’re using as a guide.

Use a ruler to draw straight lines

Step 3 – Draw line

Hold the rule in place with one hand and use the edge to guide the drawing implement. Keep the nib or point of the drawing implement at the same angle against the edge of the rule as you draw. If the position changes while drawing the line won’t be straight.

Drawing parallel lines is easy with a ruler

Step 4 – Draw other lines

Once the first line has been drawn, move the rule down to the next mark and draw that line. Try to position the rule in the same way in relation to the marks each time, for consistency. So, if you are drawing the first line from the top of the measured marks all lines should be drawn from the top of the marks.

You can check the lines are parallel by measuring their distance apart across the length of the lines.

Wonkee Donkee says "If the edge of a rule is not straight, or there are dents or burrs on the edge, it's advisable to replace it."