A framing square or a steel square is very simple yet versatile tool used by carpenters. It is essential for the carpenter who needs to do wooden frame construction. It is like a flat aluminum or steel made single piece which has two arms- a short narrower arm called as tongue set at 90 degrees to a larger arm called blade hat is 24 inches long. In this article you will learn how to use framing square.
Before going into the use of a framing square let us have a look at the features of a framing square.
Framing square has printed edges that are used to measure up to a level of accuracy of 1/32 inch.
It has a diagonal scale too, along with a board foot scale and an octagonal scale.
Most of the framing squares have rafter tables that are inscribed on the face. This table provides rafter details for different roof pitches.
The steel square is necessary tool for assembling and cutting roof of a wooden frame house. It is also helpful for lying out and cutting stair stringers.
Framing square or steel square is usually made up of aluminum or steel that is light weight materials. The arm is 2 inch wide called blade and one and a half inch narrow arm known as the tongue.
Framing squares are employed to cut rafters, stairs or any other project that requires several angled and square cuts.
Once you have learnt some simple measurement techniques, using a steel square is easy. And it does not matter if you are a math lover or not, sooner or later you will be taking help of a framing square for all complex framing requirements.
Laying a Common Rafter
This article will explain you the fundamentals of how to cut a roof rafter with the help of framing square in four simple steps. For this you will be requiring a framing square, rafter boards, pencil and 2 sawhorses.
1. Determine the Roof Pitch
The pitch or slope of a roof is measured in the units of inches of vertical (rise) per foot of (horizontal) run. A roof is said to have a 6 inch pitch if the roof has as vertical slope of 6 inch for every 12 inch horizontal measurement. Once the roof pitch selection is done, you are free to layout and cut a rafter pattern out of which other rafters can be traced and then cut.
2. Layout The Rafter Tail
You have to begin with laying out rafter tail. After the rafter is installed on the roof, bottom degree cut now becomes horizontal and in the end “plumb” cut now becomes vertical. All degree cuts are now parallel and all the plumb cuts are parallel too. Lay down a framing square flat on to the board to be used as a rafter near one end. The horizontal blade must align with the lower edge of the board at twelve inches and the vertical tongue must align at the roof pitch. Take the layout of the plumb cut and level the cut for the rafter tail. The length of plumb cut is fixed by width of dashboard.
3. Layout the Bird’s Mouth
Now it is required that you slide the framing square along the edge of the dashboard and layout the plumb cut and also level cut for the notch or as it is said bird’s mouth. The breadth of the projection is the horizontal distance that lies between the two plumb cuts. The level cut for bird’s mouth is a minimum three and a half inches and bears directly on top plate of exterior wall.
4. Find the Overall Length of Rafter
Proceed to slide Framing Square along the dashboard. Keep the blade at twelve inches and the tongue at roof pitch until the horizontal (run, total cover of the rafter) is stepped off in horizontal one foot increment. After you are done with measurement of the net span of the rafter, mark a line on the plumb cut where the rafter joins to the ridge board on the vertical tongue.
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