The basics on Speed Square (Hand Tools DIY)

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Speed Square (also called Rafter Squares) are the most basic tools required for wood-based constructions. The tool was originally invented by Albert J Swanson in 1925. Since then, this tool has become an indispensable part of woodworking.

This tool comes in handy if you want to make shelves, doorways, and other construction purposes. Knowing its basics helps you to easily work and create your desired piece at home without any professional help. People who are novel to woodworking often find it difficult to get an idea about the tools that they necessarily need. This article seeks to guide you through the basics of working with a speed square.

Different types

There are different types of speed squares available out there. Some have an open area in the middle with scribe marks for measurement purposes, some are closed.

On a general basis, speed squares are usually made of cast aluminum, but some like the “larger Swanson speed square 12″ might be made of a composite material like polystyrene.

Another variant of a speed square is the Husky expandable speed square. It is made of cast aluminum and is painted with white lettering on its surface for better vision. The Husky speed square can be expanded up to 12”.

The basics on Speed Square (Hand Tools DIY)

Things you can do with a Speed Square

  • Speed Squares are essentially used to layout lines on the material in a quick and efficient manner.
  • This tool has a protractor reading of 90°. You can primarily use it to make lines marking a 90° cut. Apart from tracing 90° lines on your board, you can also draw lines for different angles. Most of the squares have all the angles on the diagonal.
  • To make an angle, the pivot point at the base of the square comes into use. You can set the square at the pivot point on your board and then rock it to your desired angle. Let’s say you need to draw a 30° line, take your square to the edge of the material, find your line to the desired angle, make a mark, and stretch your line.
  • Another great usage of a speed square is to mark reference points on your material. Along the 90° side of the square, there are measurements. These measurements can be used as reference points for making doorways, laying out something on a wall plate.

Features of Speed Square

  • The square, along its 90° side, has a raised portion. This is often referred to as the lip of the square. The lip can be hooked on to your material, and then you can swiftly glide your square across your wooden board without lifting it. Gliding it on your material provides you with accurate measurements to effectively cut out your wooden boards. Thus, errors while working are minimized. A simple trick can be employed here to gain precision. While hooking the lip, most people run the square on the board on the side facing them. You can rather fixate it on the side opposite to you, this way, it’s easier to keep it locked into a particular position. This shall help you derive a perfect square cut.
  • In certain squares inside them, there are spaces marking an inch and a half reference. This makes your work easier since you now don’t have to turn your squares to the edge of the material every time.

Making inch and a half references

  • Rafters are structural components that are used as key components of various types of roof design. They are usually laid in series, side by side, providing a base to support roof decks and roof coverings. Speed Square is a very important tool for cutting rafters. Most squares have conversion charts from pitch to degrees inscribed in them, which are very convenient in construction.

A pitch to degree conversion chart

  • For example, a 6:12 pitch means that for every 12” inches of run, there is a 6” rise. This pitch correlates to the angle on the rafter that meets the ridge. According to the table, a 6:12 pitch translates to 26 and a half degrees. And once that is known, the cut can be made accurately as described above.

Measure it

  • Often, different variants of speed squares come with spaces in the middle where there are grooves termed as scribing points. These points come in handy for drawing one or two-inch lines down your material.
  • These squares also help you find out whether your saw is cutting perpendicular to your board/material or not. To know this, simply set your square on the base plate of your saw and then check whether your blade is perpendicular to the base plate of your saw.
  • Let’s say that you want a certain level on a wall surface to hang murals, photos. These squares help you define that level. For this, you need a Plumb Bob. A plumb bob has a string attached to it. Suspend your Plumb Bob on the surface. Now take your square and bring the string of your Plumb Bob right into your pivot line. Rotate your square right until the string unites with the 45° mark. This gives you a perfect leveled line.
  • Have you ever used a square to make a circle? Well, a speed square can help you do that. Mark on the material, a center mark for your circle, and hammer a nail into that mark. Let’s say you need a 6-inch circle for a passage for a pipe coming out from a wall. Using the square, you can mark your 3 inches from the nail; this is the radius for your circle. Set your square into the nail, then put your pencil inside the required inch groove and rotate your square. Ensure that your pencil is sharp enough for this process. It’s better than finding something circular like bottle caps around you to make a quick, perfect circle.


Thus, speed squares help you make refined cuts on your wooden bases, helping you mold the material whichever way you like. With grooves for scribing lines, spaces in between to mark reference points, the tool offers unmatched precision and accuracy.

Bonus video: The basics on a Speed square

Thank you for reading!

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