1. Measuring and Layout Tools
Unit 9
Measuring and Layout Tools
Tapes and Rules • Leveling and Plumbing Tools • Squaring Tools • Marking and Scribing Tools

2. A tape measure is used for many measuring and layout jobs.
A tape measure, or pocket tape, is probably used more often than any other measuring tool on the job. See Figure 9‑1. Tape measures come in various lengths, with 12′, 16′, 20′, 25′, 30′, and 55′ lengths being the most popular sizes. The blade of a tape measure is usually 1/2″ or 3/4″ wide. Some 25′ tapes feature a 1″ blade, allowing the blade to remain rigid for an unsupported distance up to 7′. One edge of the blade of most tape measures is marked off in inches and the other edge in feet and inches. A special identifying mark is placed every 16″ on the blade for the 16″ OC (on-center) layout of studs and floor or ceiling joists. Many tape mea- sures also have an identifying mark every 19.2″ on the blade for the 19.2″ OC layout of trusses and engineered lumber joists.

3. Tape measures are available that show English measurement on one edge and metric measurement on the other edge.
Some tape measures have English (customary) mea-surement (feet, inches, and fractions) on one edge of the blade and metric measurement (meters and millimeters) on the other edge. See Figure 9-2.

4. A steel tape is used to measure long distances.
Steel tapes are used to measure long distances. See Figure 9-3. Carpenters typically use 50′ or 100′ steel tapes with blades incremented in feet, inches, and eighths of an inch. Most steel tapes have a steel ring with a fold-out hook. The hook can be placed over the edge of an object, or the ring can be placed over a nail when extending the blade.

5. A plumb (vertical) line is always at a 90° angle to a level (horizontal) line.
The term level refers to horizontal planes. A perfectly level surface is a flat horizontal plane without high and low points. The term plumb refers to a vertical position. A plumb line is always at a right angle (90°) to a level surface. See Figure 9-4.

6. Lightweight aluminum or magnesium carpenter’s levels are generally preferred over older wood types.
A carpenter’s level, or hand level, is a hand tool used to establish level and plumb lines. See Figure 9-5. Most carpenters prefer lightweight aluminum or magnesium levels to the older wood levels as they are more durable than wood levels.

7. The center vial of a carpenter’s level is used for leveling
The center vial of a carpenter’s level is used for leveling. The end vials are used for plumbing. To ensure an accurate level reading, look straight into the vial and not at an angle.
Three slightly curved vials are set in the frame of a carpenter’s level and are protected by glass or plastic covers. The vials are partially filled with spirit alcohol that contains an air bubble. The vials at each end of a level are used to plumb objects. When a level is held in the vertical position and the air bubbles are centered between the two lines marked on the end vials, the level is exactly plumb. The center vial of the level is used to level objects. The air bubble will be centered between the two lines when the level is exactly level. See Figure 9-6.

8. A carpenter’s level should be periodically checked for accuracy.
A carpenter’s level should be handled with care, since its vials and their protective covers are easily broken. The vials on most levels can be replaced if they are broken. A new level should always be checked for accuracy. Levels should be rechecked periodically since they can become inaccurate over a period of time. Figure 9-7 shows how to test a level for accuracy.

9. The arm of a plate level can be extended to plumb a wall from the bottom plate to the top plate.
A plate level is similar to a carpenter’s level, but has an extendable arm to provide a longer reach for the level. See Figure 9-8. Plate levels are commonly used to plumb walls or level across longer horizontal distances without setting up additional leveling instruments.

10. A straightedge consisting of a piece of 3/4″ plywood with blocks at the ends and a carpenter’s level is often used when leveling or plumbing over a long distance.
A carpenter’s level is accurate only up to its length. Use a straightedge and carpenter’s level when leveling or plumbing over long distances. A straightedge is usually a piece of lumber that is perfectly straight and is the same width from one end to the other. A piece of 3/4″ plywood with a block at each end is often used for this purpose. See Figure 9-9.

11. A laser hand level is used to transfer locations from one surface to another surface which is nearby.
A laser hand level can be used as a standard carpenter’s level or it can be switched on to emit a laser beam. See Figure Laser hand levels are mounted on a tripod or placed on a flat surface. A tripod mount allows the level to be easily rotated. A laser hand level accurately projects a laser beam 50′ to 100′ with minimum beam deflection.

12. A line level has hooks so that it can be attached to a tightly stretched string.
Another way to level long distances is to use a line level. See Figure A line level is hooked over a tightly stretched string. However, this is not always an accurate method since there may be some sag in the line from which the level is hung.

13. A water level is a convenient tool to use to determine a level location in another room or otherwise obstructed location. Water levels are based on the principle that water will find its own level in a system open to atmospheric pressure.
A water level is an accurate leveling tool that is based on the principle that water will find its own level in a system open to atmospheric pressure. See Figure While water levels have largely been replaced by laser levels and other leveling instruments, water levels are a convenient tool to use to determine a level location in another room or on the opposite side of a wall. Some water levels consist of a long section of clear plastic tubing with a clear reservoir on each end, while other water levels consist of a large water reservoir at one end that is connected to clear plastic tubing. Some models of water levels are equipped with a digital readout display.

14. When using a plumb bob to plumb a wall, the distance between the line and the top of the wall is equal to the distance between the point of the plumb bob and the bottom of the wall.
A plumb bob and line are used for plumbing greater heights than can be handled by a level and straightedge. Figure 9-13 shows how a plumb bob is used. The wall is plumb when the distance between the line and the top of the wall is the same as the distance between the point of the plumb bob and the bottom of the wall. Plumb bobs range in weight from 4 oz to 48 oz.

15. Square cuts are required when framing walls and ceilings.
A 90° (right) angle is used most often for cutting and fastening together construction materials. Wall framing members and joists have square cuts at their ends. See Figure 9-14.

16. Trim pieces, such as this casing, are typically mitered at 45°.
A 45° angle is commonly used when fitting finish ma-terials, such as the trim around a window or door open-ing. See Figure 9-15.

17. A combination square is used to lay out 90° and 45° angles.
A combination square is used to lay out 90° and 45° angles. See Figure The blades of most combi-nation squares are 12″ long and are marked off in inches and fractions.

18. Set the combination square to the desired position and guide the head along the edge of a board while holding a pencil along the end of the blade.
A combination square can also be used as a marking gauge, as shown in Figure 9‑17. The head of the com-bination square is locked in the desired position and placed flush against the edge of the surface to be marked. The tip of a pencil is held firmly against the blade while the combination square is pulled along the edge.

19. The face of a framing square may include rafter and octagon tables.
The inches on the outside edges of the face of a framing square are divided into 1/16″ graduations. The inches along the inside edges of the face are divided into 1/8″ graduations. The face of a framing square typically in-cludes the manufacturer name at the corner, rafter tables on the blade, and an octagon table on the tongue. See Figure 9-18.

20. The back of a framing square may include Essex board measure and brace measure tables.
The inches at the outside edges of the back of the square are divided into 1/12″ graduations, which is useful when making scale layouts of 1″=1′-0″. The inside edge of the blade of the back of the square is divided into 1/16″ graduations. However, the inside edge of the tongue is divided into 1/10″ graduations, which is also convenient for some types of layout. See Figure 9-19.

21. Framing square applications include squaring a line across a wide board, marking a 45° angle across a wide board, and checking an inside corner for squareness.
Framing squares are used to check or square lines across wider boards or when greater accuracy is re-quired than is possible with a combination square. A framing square is also used to mark 45° angles across wide boards and check inside corners for squareness. See Figure To mark a 45° angle across a wide board, line up a number on the blade with the edge of the board and then line up the same number on the tongue with the edge of the board.

22. The octagon table is used to shape squared lumber or timbers into an octagonal shape.
To lay out an octagonal shape on a piece of squared stock, first lay out the center of each side of the stock. See Figure In this example, the stock is 8″ along each side. Using the octagonal table and dividers, set the dividers to 8 units since the stock measures 8″ along each side. Transfer the 8-unit distance to the stock, laying out the distance on each side of the centerline. Using a pencil, connect these points to form an octagon.

23. The protractor scale of a Speed® Square is used to lay out angles ranging from 0° to 90°. The common, hip, and valley scales are used to lay out the plumb and seat cuts for common, hip, and valley roof rafters.
A Speed® Square, also referred to as a pocket square or rafter angle square, is used to lay out angles from 0° to 90° and to lay out the angled cuts for roof rafters. See Figure In addition, a Speed Square may also be used as a saw guide when crosscutting lumber. In recent years, the popularity of the Speed Square has increased due to its compact size and versatility. Additional in-formation on the use of Speed Squares is included in units 46 to 49.

24. A sliding T-bevel is used to transfer angles
A sliding T-bevel is used to transfer angles. The wing nut tightens the blade in place.
The sliding T-bevel, or bevel square, is used to transfer and test angles. The blade is adjusted to the desired angle and is locked into place with a wing nut. See Figure A sliding T-bevel is considered essential by experienced carpenters.

25. A try square is used to lay out 90° angles.
Another type of squaring tool used by carpenters is the try square. See Figure A try square has a short, fixed blade and is used to lay out 90° angles.

26. An angle divider is used to lay out miter cuts on molding for walls that meet at angles other than 90°. First, the angle divider is adjusted to fit the inside corner. Then it is used to mark the miter cut on the molding.
An angle divider is a layout tool used to lay out joints that meet at angles other than 90°. See Figure When laying out miter cuts on wall molding, an angle divider is first placed in the corner in which the molding will fit and locked into position using the thumbscrew. The angle divider is then positioned on the molding and the desired angle is marked along one of the legs.

27. A scriber is used to mark a line when a close fit is required between the edge of a piece of material and an irregular surface.
A scriber has two legs—one with a steel point and one holding a pencil. See Figure A scriber is used when a close fit is required between two pieces of ma-terial when one of the surfaces is irregular. The steel point is placed against the irregular surface and is pulled along the surface, transferring the irregularities to the mating surface.

28. Dividers are used to draw arcs and circles and can also be used as a scriber.
Dividers are used to draw arcs and circles or lay out equal spaces. One metal leg is easily replaced with a pencil if desired. See Figure Dividers can also be used when a close fit is required between two mating surfaces. When using dividers for this purpose, bend the point of the removable leg slightly outward.

29. A scratch awl is used to start holes for wood screws or mark lines on materials that will not show a pencil line.
A scratch awl is used to mark lines on materials that will not show a pencil line. Scratch awls are also used to start holes for wood screws, especially in hardwood lumber. See Figure 9-28.

30. A center punch is used to mark holes to be drilled in hard wood or metal.
A center punch is struck with a hammer to mark holes to be drilled in hard wood or metal. The indentation in the metal will prevent the drill bit from “skating” across the surface. See Figure 9-29.

31. Square gauges are attached to a framing square to lay out angle cuts for roof rafters as well as tread and riser cuts for stair stringers.
Square gauges, or stair gauges, are used with a framing square to lay out roof rafters and stair stringers. The square gauges are clamped to the blade and tongue of a framing square to ensure the same angle is laid out for the rafters and stringers. See Figure 9-30.

32. A chalk line reel is used to snap straight lines on flat surfaces.
A chalk line reel, also known as a chalk box, is used to snap straight lines on flat surfaces. See Figure The reel is filled with colored powdered chalk, which coats the line (string) wound up in it. A tapered ring at the end of the line can be hooked on a nail while the line is unwound. The line is stretched taut and then pulled straight up and released to snap a chalk line on the material beneath it. After snapping a few lines, the line will need to be rewound to recoat it.