Rafter blocks are a great value. They are very cheap and very useful. In fact, any contractor worth their salt will have one on hand most of the time. The reason for this is that you can accomplish many different tasks. It offers straight edges, allows for quick scribing, and angles and spacing can be found quickly. If you feel like you're not getting the most out of your stuff, we've laid out the basics of how to use rafter blocks.
For reference, rafter blocks are sometimes called "velocity blocks", based on Swanson's original model.
How to Mark and Measure with Rafter Square
Rafter squares are used for quick scribing. It has a straight edge with a lip and is available in 90° and 45° angles. With the edge of the rafters against the boards, you can mark perfect vertical and 45° lines. You can do this job as quickly as sliding the rafters.
It also includes a scribe bar below its ruler. Scribe rods have notches every 1/4 inch. So let's say you need to trim 1-1/2 inches from the sides of the board. Simply place the pencil into the appropriate notch and run the edge of the Speed Square along the edge of the board.
How to Cut Straight with a Circular Saw
By the way, the lipped fence on the tool lets you use the rafter square as a guide. This helps you make straight cuts with your circular saw. No more clumsy freehand circular saw cutting, my friend. To hold the rafters in place, slide the circular saw down the edge. This results in perfect 90° and 45° cuts every time. We have a video showing you how it works!
How to Cutout with Diamonds
Although Swanson originally invented the "speed cube" rafter square, there are many other manufacturers of the tool that make something similar. An advantage over the original, however, is that Swanson included its patented diamond cutout, which allows the user to make squares from diagonal lines drawn from the board.
How to Use the Rafter Square for Stretch and Pitch
The bottom edge has all your angles marked so you can use the rafter squares to find and mark any angles you may need. Simply move the pivot point to the edge of the board so that the edge of the board is aligned with your desired angle.
You can use rafter blocks to find courts. In fact, finding the slope of a roof was the motivation behind the tool's original invention, hence the name. The rafter square has two dedicated protractor angle guides inside the tool, marked with common rafter angles and "hip valley" angles.
If you are working without a spirit level, you can also use this tool to find your spirit level. Basically, you'll rest the long side of the square against your surface, and hang the plumb bob from the pivot point. Gravity takes care of the rest, and you'll know your surface is level if the line hangs at 45°.
Admittedly, this article is more of a simplified overview of how to use rafter blocks. To purchase one of these handy multi-tools, visit our friends at AcmeTools.