Featured image: [Image of a speed square being used to measure an angle]
The speed square is a versatile tool that can be used for a variety of tasks, from framing to roofing. It’s an essential tool for any carpenter or woodworker. In this article, we’ll show you how to use a speed square to perform some of the most common tasks. We’ll start with the basics, and then we’ll move on to some more advanced techniques.
The speed square is a triangular tool with two scales on the long edge and one scale on the short edge. The long scales are used for measuring angles, and the short scale is used for measuring distances. To use the speed square to measure an angle, simply place the square on the workpiece so that the two long edges are aligned with the sides of the angle. Then, read the angle measurement on the long scale.
To use the speed square to measure a distance, simply place the square on the workpiece so that the short edge is aligned with the distance to be measured. Then, read the distance measurement on the short scale. The speed square can also be used to find the center of a circle or to draw a perpendicular line. To find the center of a circle, simply place the square on the circle so that the two long edges are tangent to the circle. Then, mark the center of the circle with a pencil.
Understanding the Basics of a Speed Square
A speed square is a versatile tool widely used in construction and woodworking projects. It combines various scales and functions into a single, compact device. Understanding its basic components and how they work is crucial for effectively utilizing a speed square:
Body:
The body of the speed square is typically made of durable plastic, aluminum, or stainless steel. It features a right angle (90°) and two sides with different measurements and scales.
Hypothenuse and Tongue:
The hypotenuse is the longest side of the speed square, forming the 90° angle. It has various markings, including common rafter scales, which are necessary for calculating roof pitch and rafter lengths.
The tongue is the shorter side perpendicular to the hypotenuse. It has smaller scales, such as the 16″ and 18″ octagon scales, used for measuring and laying out octagonal shapes.
Common Rafter Scales:
Common rafter scales are essential for sizing rafters and calculating roof pitches. They are marked on both the hypotenuse and tongue of the speed square.
**To use the common rafter scale:**
- Identify the roof pitch or rise per foot on the appropriate scale.
- Align the hypotenuse (for rafters with a plumb cut) or the tongue (for rafters with a square cut) with the pitch mark.
- Read the measurement where the desired run meets the scale, providing the required rafter length.
| Side of Speed Square | Scale | Use |
|---|---|---|
| Tongue | 16″ Octagon | Laying out octagonal shapes |
| Hypotenuse | 24″ Common Rafter | Calculating roof pitch and rafter lengths |
| Hypotenuse | 16″ Common Rafter | Calculating rafters with a plumb cut |
| Tongue | 12″ Common Rafter | Calculating rafters with a square cut |
Measuring and Marking Angled Cuts
To mark angled cuts, turn the speed square so that its body is aligned with one edge of the material. Mark the desired length on the other edge using the appropriate graduation on the speed square.
For example, to mark a 45-degree cut on a 2×4, place the speed square on the 2×4 so that the 0-degree graduation is aligned with one edge and the 45-degree graduation is aligned with the other edge. Mark a line along the 45-degree graduation.
Using the Speed Square for Other Angled Cuts
The speed square can be used to mark angled cuts other than 45 degrees. To do this, use the following steps:
- Align the body of the speed square with one edge of the material.
- Find the graduation on the speed square that corresponds to the desired angle.
- Mark a line along the graduation.
The following table provides a list of common angled cuts and the corresponding graduations on the speed square:
| Angle | Graduation |
|---|---|
| 30 degrees | ½ inch mark |
| 45 degrees | 1 inch mark |
| 60 degrees | 1½ inch mark |
| 75 degrees | 2 inch mark |
| 90 degrees | 0-degree graduation |
Determining Rafter Cuts
One of the most common uses for a speed square is to determine rafter cuts. Here’s how to do it:
1. **Mark the rafter length on the tongue of the square.** This is the distance from the bottom of the rafter to the top of the roof.
2. **Align the tongue of the square with the edge of the rafter.** Make sure that the 0-inch mark on the square is aligned with the bottom of the rafter.
3. **Read the measurement at the rafter length you marked in step 1.** This is the amount of overhang you will have at the eaves.
For example, if you marked the rafter length as 12 feet and the measurement at that point is 6 inches, you will have a 6-inch overhang at the eaves.
4. **Use the square to mark the plumb cut on the rafter.** This is the cut that will be perpendicular to the rafter.
5. **Use the square to mark the seat cut on the rafter.** This is the cut that will rest on the top plate of the wall.
Here is a table to guide you:
| Roof Pitch | Common Rafter Cut | Hip/Valley Rafter Cut |
|---|---|---|
| 1/12 | 33.7° | 45° |
| 2/12 | 38.7° | 45° |
| 3/12 | 42.8° | 45° |
| 4/12 | 45° | 45° |
| 5/12 | 46.8° | 45° |
| 6/12 | 49.4° | 45° |
| 7/12 | 51.9° | 45° |
| 8/12 | 54.4° | 45° |
| 9/12 | 56.3° | 45° |
| 10/12 | 57.9° | 45° |
| 11/12 | 59.4° | 45° |
| 12/12 | 60° | 45° |
Finding Roof Pitch and Slope
Step 1: Mark the Roof’s Rise and Run
Measure the vertical rise (height) of the roof from the eaves to the ridge. Mark this distance on your speed square. Next, measure the horizontal run of the roof from the eaves to the ridge. Mark this distance on the square at a 90-degree angle to the rise measurement.
Step 2: Align with Common or Hip/Valley Tables
For pitched roofs, align the rise and run measurements with the "Common" tables on the square. For hipped or valley roofs, use the "Hip/Valley" tables instead. Ensure that the measurements align exactly with the grid lines on the square.
Step 3: Read the Pitch or Slope
The intersection of the rise and run measurements on the speed square indicates the roof’s pitch or slope. The pitch is typically expressed as a ratio of the rise to the run, for example, 4:12. The slope is a decimal representation of the pitch, in this case, 0.33 (4 divided by 12).
Step 4: Calculating Roof Area Using Pitch and Slope
To calculate the roof area using the pitch or slope:
- For pitched roofs: Area = 1/2 x run x rise
- For hipped or valley roofs: Area = 1/6 x circumference x rise
- Circumference = 2 x (length + width)
| Roof Type | Area Formula |
|---|---|
| Pitched | 1/2 x run x rise |
| Hipped or Valley | 1/6 x circumference x rise |
Once you have calculated the roof area, you can use this information for various roofing tasks, such as estimating material quantities and planning roof construction.
Squaring Up Corners
To square up a corner using a speed square, follow these steps:
- Lay the speed square along the edge of the first board, with the 0-inch mark aligned with the corner.
- Hold the speed square in place and rotate the second board until the edge aligns with the 90-degree mark on the speed square.
- Secure the second board in place with nails or screws.
Framing Walls
To frame walls using a speed square, follow these steps:
- Draw a perpendicular line on the floor or ceiling, where the wall will be placed.
- Place the speed square on the line, with the 0-inch mark at the corner and the 90-degree mark along the perpendicular line.
- Mark the location of the studs on the speed square.
- Transfer the stud marks to the floor or ceiling using a pencil or chalk line.
- Cut the studs to length and install them according to the stud marks.
Using the Tables
Speed squares often have tables printed on them for quick reference. These tables can be used for a variety of tasks, such as finding the rise and run of a roof, calculating the area of a triangle, or converting inches to feet and vice versa.
| Task | Use the Table |
|---|---|
| Find the Rise and Run of a Roof | Use the “Roof Pitch” table |
| Calculate the Area of a Triangle | Use the “Area of Triangle” table |
| Convert Inches to Feet and Vice Versa | Use the “Inch-Foot Conversion Table” |
Checking for Level and Plumb
### Using the Horizontal Level Bubble
Place the speed square on the surface you want to check for level. Align the horizontal edge of the square with the horizon or a reference line. The bubble in the level should center between the two lines marked on the square, indicating that the surface is level.
### Using the Vertical Plumb Bubble
Hang the speed square vertically with the plumb bubble centered in the rectangular window. Check if the bubble is aligned with the vertical line on the square. If the bubble is not centered, the surface is not plumb.
Advanced Usage: Using the 6″ End as a Plumb Line
Extend the 6″ end of the speed square over the edge of the surface. Hold the square firmly against the surface and release the plumb bob so that it hangs freely. The plumb bob will indicate the vertical plumb line.
This method is particularly useful when checking for plumb or transferring a plumb reference from one surface to another. The 6″ end of the speed square acts as an extended plumb line, allowing you to check for plumb over longer distances or in hard-to-reach areas.
Additional Notes:
| Feature | Usage |
|---|---|
| 45° and 90° Angles | Verifying squareness, marking miters, framing angles |
| Scribing Tool | Transferring measurements or marking parallel lines |
| Rafter Table | Calculating rafter lengths and cuts for roofs |
Laying Out Hip and Valley Rafters
When it comes to cutting hip and valley rafters, the speed square comes in handy as a powerful tool. Here’s a step-by-step guide to using it:
8. Determine the Common Rafter Length
To find the common rafter length, follow these steps:
- Place the square on the top plate with the “tongue” (the short arm) resting at the outside edge of the wall.
- Move the square along the top plate until the “body” (the long arm) touches the center of the ridge board.
- Read the measurement where the “heel” (the pointed end of the body) meets the top plate. This is the common rafter length.
For example, if the measurement is 12 inches, the common rafter will be 12 inches in length.
| Measurement on “Heel” | Common Rafter Length |
|---|---|
| 12 inches | 12 inches |
| 14 inches | 14 inches |
| 16 inches | 16 inches |
By following these steps, you can accurately determine the common rafter length, which is crucial for cutting hip and valley rafters.
Troubleshooting Common Speed Square Problems
1. The speed square is not accurate
There are a few reasons why your speed square might not be accurate. First, make sure that the square is clean and free of debris. Any dirt or sawdust can interfere with the square’s accuracy. Second, check the square for any damage. If the square is bent or cracked, it will not be accurate. Finally, make sure that you are using the square correctly. The square should be held against the workpiece with the square’s edge parallel to the edge of the workpiece.
2. The speed square is difficult to read
If you are having difficulty reading the speed square, there are a few things you can do. First, try using the square in a well-lit area. Second, clean the square with a damp cloth. Any dirt or sawdust can make the square difficult to read. Finally, you can try using a magnifying glass to help you read the square.
3. The speed square is not durable
If your speed square is not durable, there are a few things you can do. First, make sure that you are storing the square in a dry place. Second, avoid exposing the square to extreme temperatures. Third, do not use the square as a hammer or pry bar.
4. The speed square is too small
If your speed square is too small, you can purchase a larger square. Speed squares are available in a variety of sizes, so you can find one that is the right size for your needs.
5. The speed square is too large
If your speed square is too large, you can cut it down to a smaller size. To do this, use a hacksaw to cut the square to the desired size. Be sure to wear safety glasses when cutting the square.
6. The speed square is not square
If your speed square is not square, you can adjust it using a try square. To do this, place the speed square on the try square and adjust the speed square until it is square. Once the speed square is square, tighten the screws to hold it in place.
7. The speed square is not level
If your speed square is not level, you can adjust it using a level. To do this, place the speed square on the level and adjust the speed square until it is level. Once the speed square is level, tighten the screws to hold it in place.
8. The speed square is not plumb
If your speed square is not plumb, you can adjust it using a plumb bob. To do this, tie a plumb bob to the speed square and adjust the speed square until the plumb bob is centered. Once the speed square is plumb, tighten the screws to hold it in place.
9. The speed square is not parallel
If your speed square is not parallel, you can adjust it using a parallel ruler. To do this, place the speed square on the parallel ruler and adjust the speed square until it is parallel. Once the speed square is parallel, tighten the screws to hold it in place.
10. The speed square is not perpendicular
If your speed square is not perpendicular, you can adjust it using a framing square. To do this, place the speed square on the framing square and adjust the speed square until it is perpendicular. Once the speed square is perpendicular, tighten the screws to hold it in place.
| Problem | Cause | Solution |
|---|---|---|
| The speed square is not accurate | The square is dirty, damaged, or not being used correctly | Clean the square, check for damage, and use the square correctly |
| The speed square is difficult to read | The square is in a poorly lit area, dirty, or too small | Use the square in a well-lit area, clean the square, or use a magnifying glass |
| The speed square is not durable | The square is stored in a damp place, exposed to extreme temperatures, or used as a hammer or pry bar | Store the square in a dry place, avoid exposing it to extreme temperatures, and do not use it as a hammer or pry bar |
| The speed square is too small | The square is not the right size for the job | Purchase a larger square |
| The speed square is too large | The square is not the right size for the job | Cut the square down to a smaller size using a hacksaw |
| The speed square is not square | The square is not adjusted correctly | Adjust the square using a try square |
| The speed square is not level | The square is not adjusted correctly | Adjust the square using a level |
| The speed square is not plumb | The square is not adjusted correctly | Adjust the square using a plumb bob |
| The speed square is not parallel | The square is not adjusted correctly | Adjust the square using a parallel ruler |
| The speed square is not perpendicular | The square is not adjusted correctly | Adjust the square using a framing square |
How to Use a Speed Square
A speed square is a versatile tool that can be used for a variety of tasks, including measuring angles, finding rafter lengths, and laying out stairs. It is an essential tool for any carpenter or woodworker.
To use a speed square, first place it on the surface you are measuring. Align the edge of the square with the edge of the surface, and then read the angle measurement on the scale. The scale is usually marked in degrees, but it can also be marked in inches, feet, or other units.
To find the rafter length, first measure the span of the roof. Then, use the speed square to find the rafter length corresponding to the span and the desired roof pitch. The roof pitch is the angle of the roof, and it is usually expressed as a ratio of the height of the roof to the span of the roof.
To lay out stairs, first measure the rise and run of the stairs. The rise is the height of each step, and the run is the depth of each step. Then, use the speed square to mark the location of each step on the stringer board. The stringer board is the board that supports the treads and risers of the stairs.
People Also Ask
What is a speed square used for?
A speed square is a versatile tool that can be used for a variety of tasks, including measuring angles, finding rafter lengths, and laying out stairs.
How do I use a speed square to find the rafter length?
To find the rafter length, first measure the span of the roof. Then, use the speed square to find the rafter length corresponding to the span and the desired roof pitch.
How do I use a speed square to lay out stairs?
To lay out stairs, first measure the rise and run of the stairs. Then, use the speed square to mark the location of each step on the stringer board.
