The Speed ​​Square is arguably one of the most useful tools when it comes to construction. Originally designed for use in the framing of houses, and sometimes referred to as a rafter square, it facilitates layout operations. It features markings that help speed up common repetitive procedures when framing walls or cutting rafters. Although originally developed by the Swanson Tool Company, there are now dozens of companies that manufacture similar rafter squares. However, Swanson Speed ​​Squares generally come with more features than others.

If you get the Speed ​​Square Pro, like I did, it comes with Swanson’s Blue Book, which has instructions and explanations for the geometry, calculation and layout of virtually any rafter configuration. . If you’re not a craft builder, framing every day, this is a fantastic resource. Aside from framing, the Speed ​​Square is used on just about every woodworking project I do – it’s one of my most used tools. Build sheds, shelves, firewood racks, picnic tables, Adirondack chairs, workbenches, sawhorses. You name it, and a speed square will come in handy for doing so.

While some people find all of the markings on the Speed ​​Square a little intimidating at first, they’re not hard to understand once you see how they’re used. Below we will explain the eight most common uses of the tool.

Marking of right angles

Bradley Ford

Mark any angle

Serve as a saw guide

use a speed square as a saw guide
By holding the lip of the speed square against the bottom edge and pressing down on the top, you can use it as a saw guide to get perfectly straight cuts. You can also flip it over to cut at a 45 degree angle or rotate it on the pivot point to cut at any angle.

Bradley Ford

Square the joints

check square with speed square
The Speed ​​Square’s flat base allows you to easily check that studs or joints are square.

Bradley Ford

Marking a line parallel to an edge

Arrangement of top and bottom plates for a wall

Arrangement of plumb cuts on the top and tail of the rafters

mark a rafter plumb cut
Plumb cuts are the angled cuts on the rafters where they meet the ridge beam, and sometimes on the tail that overhangs the exterior wall. These are called plumb cuts because when the rafter is installed, the face of the cut will be perpendicular to the level (straight from top to bottom). You mark plumb cut lines by turning the square over the pivot point and lining up the “common” number with the edge of the rafter. These numbers represent the pitch of the roof, which will be referred to as “X” over 12, where “X” is the number of inches the roof rises over 12 horizontal inches. (This is also known as “rise” over “run”.) A 45 degree angle would be 12 by 12. Here I’m using 6, for a 6 by 12 pitch.

Bradley Ford

Marking of Birdsmouth cuts on the rafters

This is just a sampling of what you can do with Swanson’s Speed ​​Square. For more complex setups, check out the brand’s Blue Book I mentioned.