The main resources made use of in frame construction are lumber and hardware. This article includes brief information on the types and sizes of lumber in addition to a description of several metallic fasteners.
Lumber or timber varies widely in structural characteristics. A carpenter or woodworker must have an understanding of lumber to ensure that he is able to select the most suitable material for every project. This article covers the kinds, usual sizes, and uses of lumber for construction carpentry. In addition it covers the ways of measuring lumber quantities with regard to board feet, which is the unit in which it is usually ordered.
Lumber, the way it is obtained from the sawmill, is split into three main classes: yard lumber, structural material, and factory and shop lumber. Having said that, we will restrict this article to only yard lumber. It is classified according to quality. The carpenter must decide on a quality which is appropriate for the intended purpose. Nevertheless, he or she must exercise economy by not selecting a better (and therefore more expensive) grade than is required.
Lumber is subdivided into classifications of select lumber and common lumber.
Select lumber is of a good physical appearance and finish. It is identified from the following grade names to compare and contrast quality:
Grade A is correct for natural finishes and is practically clear.
Grade B is correct for natural finishes, is of high quality, and is generally clear.
Grade C is correct for high-quality paint finishes.
Grade D is correct for paint finishes between high-finishing grades and common grades and possesses to a degree the character of both.
Common Lumber. Common lumber is suitable for general construction and utility purposes. It is identified from the following grade names to compare and contrast quality:
No. 1 common is suitable for use without waste, you’ll find it sound and tight knotted, and also it is actually regarded as watertight lumber.
No. 2 common is less restricted in quality than No. 1, but of similar general quality. It is usually utilized for framing, sheathing, along with other structural forms in which the stress or strain is actually not too great.
No. 3 common permits some waste, and it’s also lower in quality than No. 2. It is useful for rough work as footing, guardrails, and rough flooring.
No. 4 common permits waste, is of poor quality, and could have coarse features for example decay and holes. It is used for sheathing, subfloors, and roof boards within the lower priced types of construction, but its most prominent industrial outlet is for boxes and crates.
No. 5 common is not manufactured in certain varieties of lumber. It is used for boxes, crates, and dunnage, for which the quality requirement can be extremely low.
In frame construction, lumber is employed mainly for the frame and walls.
Frames. Building frames are the wood forms constructed to support the finished members of a structure.
These include posts, girders (beams), scabs, joists, subfloors, sole plates, knee braces, top plates, and rafters. Softwoods are frequently used for wood framing quite a few other construction purposes.
No. 2 common lumber is utilized for framing. Heavy frame components, for example beams and girders, are manufactured by combining several components of framing material.
Walls. The outside wall of a frame structure normally has three layers: sheathing, building paper, and siding. Sheathing and siding lumber are typically grade No. 2 common softwood, which can be with solid knots, no voids.
Siding is either vertically or horizontally applied. Theater construction may limit available material to lap siding for both vertical and horizontal surfaces. For local purchase, there are a number of types of drop and bevel siding, that can be applied horizontally.
Lumber is generally sawn into standard dimensions (length, width, and thickness). This provides uniformity in planning structures as well as in ordering materials. Standards have been established for dimension differences relating to the cited dimensions of lumber and its standard sizes when dressed. Quoted size denotes dimensions before surfacing. These dimension differences has to be taken into account. An illustration of the dimension difference is the common 2 x 4. The customary quoted size 2 x 4 will be the rough or nominal dimension, however the true dressed size is 1 1/2 x 3 1/2 inches. Lumber is sawn in standard sizes intended for light framing
Thickness: 1, 2, and 4 inches.
Width: 2, 4, 6, 8, 10, and 12 inches.
Length: 8, 10, 12, 14, 16, 18, and 20 feet.
The exact dimensions of dressed lumber are less than the sawn dimensions due to drying and planing (or finishing).
Plywood is usually 4 x 8 feet and varies from 1/8 to 1 inch in thickness.
The volume of lumber required is measured in board feet. A board foot is one measure representing an area of 1 foot by 1 foot, 1 inch thick. Thus, a board that is 1 inch thick, 1 foot wide, and 1 foot long measures 1 board foot. A board that is 1 inch thick, 1 foot wide, and 12 feet long measures 12 board feet.
To ascertain the number of board feet in one or maybe more pieces of lumber, use the following formula:
Board feet = N x T(in) x W(in) x L(ft) or N x T(in) x W(in) x L(in)
where:- N = number of lumber pieces, T = thickness, W = width, L= length
A wide variety of fasteners are used for frame construction. These fasteners are all made of metal. They are classified as nails, screws, bolts, driftpins, corrugated fasteners, and timber connectors.
Nails, the most common type of metal fasteners, are available in a wide range of types and sizes. The common nail is designed for rough framing. The box nail is used for toenailing and light work in frame construction. The casing nail is used in finished carpentry work to fasten doors and window casings and other wood trim. The finishing nail and brad are used for light, wood-trim material and are easy to drive below the surface of lumber with a nail set.
Nails are typically considered the least expensive and least difficult fasteners to be applied. Some nails are specially coated with zinc, cement, or resin materials. Quite a few have threading for extra holding power. Nails are manufactured from a large number of materials, including iron, steel, copper, bronze, aluminum, and stainless steel.
The size of a nail is measured in a unit known as a penny. Penny is abbreviated with the lowercase letter d. It indicates the length of the nail. A 6d nail is 2 inches long; a 10d nail is 3 inches long. These measurements apply to common, box, casing, and finish nails only.
In former practice, the size of nails was specified according to the number of pounds that one thousand of any variety would weigh. Thus the term sixpenny and eight-penny referred to varieties which would weigh six and eight pounds per thousand, respectively, penny being a corruption of pound. Even in current practice, certain sizes are still roughly specified as three, four, six, eight, ten, twenty and thirty-penny.
Brads and small box nails are identified by their actual length and gauge number.
A nail, regardless of the type, should be a minimum of three times as long as the thickness of the wood it is expected to hold. Two thirds of the length of the nail is driven right into the other piece of wood for proper anchorage. The remaining one-third of the length affords the called for anchorage of the piece being fastened.
Protruding nails ought to be bent over to prevent damage to materials and injury to people.
In all but in rough work, the nail should not be driven entirely in with the hammer or the wood will be marred. A nailset or punch should be used to set the head of the nail slightly below the surface of the wood-about one thirty-second of an inch. A finger placed against the side of the nailset and allowed to rest on the piece, of wood aids greatly in guiding the set, which otherwise might jump off the nail head when the blow is struck and indent the wood.
Withdrawing Nails. Should it be necessary to withdraw a nail, place a block of wood under the head of the hammer, to prevent marring the surface of the wood. If the nail is a long one, the size of the block used should be increased as the nail comes out, so that the nail will not be bent.
There are some general rules that must be followed in the using of nails in building. Nails ought to be driven at an angle slightly toward one another to improve their retaining power. You need to be careful in placing nails to produce the maximum holding power. Nails driven with the grain usually do not hold as well as nails driven across the grain. Just a few nails of proper size and type, effectively positioned and properly driven, will hold considerably better than a large number driven close together.
Annular and spiral nails are threaded for greater holding power. These are generally suitable for fastening paneling or plywood flooring. The drywall nail is utilized for hanging drywall and it has a particular coating in order to avoid rust. Roofing nails normally are not specified by the penny system; they are referenced by length. They come in lengths from 3/4 to 2 inches and possess large heads. The double-headed nail, or duplex-head nail, is employed for temporary construction, including form work or scaffolding. The double exactly this nail makes it easy to remove when forms or scaffolding are taken down. Nails for power nailing may be found in rolls or clips for easy loading into a nailgun. These are generally coated for easier driving and greater gripping power.
Screws will be more expensive than nails both in time and cash, but are sometimes necessary for better results. They offer far more holding power than nails and can be easily tightened to draw material securely together. Screws are neater in looks and may also be withdrawn without damaging the material. The common wood screw is normally manufactured from unhardened steel, stainless steel, aluminum, or brass. The steel might be bright-finished or blue, or it could be zinc, cadmium, or chrome plated. Wood screws are threaded for roughly 2/3 of the length of the screw from a gimlet point and also have a slotted head. Screws vary in length and size of shaft. Each length is manufactured in a number of shaft sizes recognised by way of a number that shows relative differences in the diameter of the screws. Proper screw size number indicates the wire gauge of the body, the drill or bit size for the body hold, and also the drill or bit size for the starter hole.
Both slotted and cross headed flathead and oval-head screws are countersunk enough to permit a covering material to be employed. Slotted roundhead and cross headed roundhead screws are definitely not countersunk, however they are driven firmly flush with the surface.
Screws, like nails, are made entirely by machinery. They are packed in pasteboard boxes and sold (usually) by the gross. The size of a screw is designated by the length in inches and the size of the wire from which it is made;:thus, 1 inch No. 10 flathead bright screw.
Flathead screws are used for ordinary work. Roundhead screws are used because they are more ornamental. Either kind may be made of steel or brass.
Steel screws are often blued by treating them with heat or an acid.
Fastening with Screws.
Where two pieces of hard wood are to be fastened with screws, a hole just large enough to take in the shank of the screw must be bored in the upper part. In the lower part, a hole should be bored just large enough to take in the core of the screw snugly. For flathead screws, the hole should be countersunk so that the head may be flush or sunk slightly below the surface of the wood.
Wood screws are designated based on head style. The most commonly encountered forms are flathead, oval head, and roundhead with either slotted or cross heads.
Their sizes range between 1/4 to 6 inches. Screw sizes up to 1 inch increase by eighths, screws from 1 to 3 inches increase by quarters, and screws from 3 to 6 inches increase by half inches.
To prepare wood for accepting the screws a pilot hole the diameter of the screw is bored into the piece of wood being fastened. A smaller starter hole will then be bored into the piece of wood that is to act as anchor or to hold the threads of the screws. The starter hole has got a diameter less than that of the screw threads and is drilled to a depth of 1/2 or 2/3 the length of the threads to be anchored. This technique assures accuracy in placing the screws, reduces the possibility of splitting the wood, and cuts down on the time required.
Lag Screws. (Sometimes called Lag Bolts)
Wood-screw type. These are generally longer and heavier compared to the common wood screw and possess coarser threads, which extend from a cone or gimlet point a little more than half the length of the screw. Square-head and hexagon-head lag screws are often positioned by using a wrench. They are utilized when ordinary wood screws might be too short or too light and spikes would not be sufficiently strong. Put together with expansion anchors, lag screws are widely used to frame timbers to existing masonry.
Sheet-metal screws can be used for the assembly of metal parts. These screws are steel or brass with four varieties of heads: flat, round, oval, and McAllister.
Bolts are used when great strength is needed or when the work has to be taken apart often. Nuts usually are used for fastening bolts. The use of washers between the nut and wood surfaces, or between both the nut and the head and their opposing surfaces, will avoid damaging the surfaces and definitely will allow even more torque in tightening. Bolts are selected by length, diameter, threads, design of head, and type.
Carriage bolts are available in three types: square neck, finned neck, and ribbed neck.
In every type of carriage bolt, the part of the shank immediately below the head grips the materials into which the bolt is inserted. This prevents the bolt from turning every time a nut is tightened down on it or removed.
The finned carriage bolt has two or more fins extending from the head to the shank. The ribbed type has longitudinal ribs, splines, or serrations on all or part of a shoulder, located immediately below the head.
Holes bored to receive carriage bolts are bored to a tight fit for the body of the bolt and counterbored to enable the head of the bolt to fit flush with or below the top of the material being fastened. The bolt will then be driven into the hole using a hammer. Carriage bolts are predominantlyfor wood-to-wood use, but could also be used for wood-to-metal. If put to use for wood-to-metal application, the bolt head should be fitted to the wooden item. Metal surfaces are occasionally predrilled and countersunk to allow for the use of carriage bolts for metal-to-metal fastening. Carriage bolts are obtainable from 1/4 to 1 inch in diameter and from 3/4 to 20 inches long. A common flat washer ought to be made use of between the nut and the wood surface with carriage bolts.
Machine bolts (or cap screws) are manufactured with cut national fine or national coarse threads. These threads extend from twice the diameter of the bolt plus 1/4 inch (for bolts less than 6 inches in length) to double the diameter of the bolt plus 1/2 inch (for bolts over 6 inches in length). Machine bolts are precision made and usually applied metal to metal where close tolerance is required. The head may be square, hexagon, double hexagon, rounded, or flat countersunk. The nut usually corresponds in shape to the head of the bolt with which it is used. (Machine bolts are externally driven only.)
A machine bolt is selected according to head style, length, diameter, and type of thread. The opening through which the bolt is to pass is bored to the same diameter as the bolt. Machine bolts come in diameters from 1/4 to 3 inches and may be obtained in any length desired.
Stove Bolts. Stove bolts are less accurately made than machine bolts. They may have either flat or round slotted heads and also have threads extending almost the full length of the body.
Stove bolts are typically used with square nuts and can be applied metal to metal, wood to wood, or wood to metal. If flat headed, they may be countersunk; if roundheaded, you can use them flush with the surface.
Expansion Bolts. An expansion bolt is really a bolt used combined with an expansion shield, and that is usually made of lead or plastic, to provide anchorage in substances in which a threaded fastener isunusable. The shield (or expansion anchor) is inserted in a predrilled hole and expands as soon as the bolt is driven into it. Wedged firmly within the hole, the shield behaves as a secure base for the grip of the fastener. The expansion shield can be utilized with a nail, screw, or bolt. The shield might be obtained separately or could include the nail, screw, or bolt.
Driftpins (called driftbolts for supply purposes) are long, heavy, threadless bolts utilized to hold heavy pieces of timber together. Driftpins have heads, and they also vary in diameter from 1/2 to 1 inch, and in length from 18 to 26 inches.
To use the driftpin, drillmake a hole in the timber slightly smaller than the diameter of the pin. Drive the pin into the hole. It is held in place by the compression action of the wood.
Corrugated fasteners are used to fasten joints and splices in small boards, particularly in miter joints and butt joints. Corrugated fasteners are made of 18- to 22-gauge sheet metal with alternate ridges and grooves; the ridges vary from 3/16 to 5/16 inch, center to center. One end is cut square; the other end is sharpened, with beveled edges.
There are two types of corrugated fasteners: one with ridges running parallel, the other with ridges running at a slight angle to one another. The latter type tends to compress the material, since the ridges and grooves are closer at the top than at the bottom.
Corrugated fasteners vary from 5/8 to 1 1/8 inches wide and from 1/4 to 3/4 inch long. Ridges on the fasteners range from three to six ridges per fastener.
Corrugated fasteners are a great advantage when used to fasten parallel boards together (as in fastening tabletops), to make any type of joint, and to substitute for nails where nails may split the lumber.
The fasteners have a greater holding power in small lumber than nails do.
Timber connectors are metal devices for increasing the joint strength in timber structures. Efficient connections for either timber-to-timber joints or timber-to-steel joints are provided by the several types of timber connectors. The correct type is determined by the type of joint to be produced as well as the load to be carried. The connectors:-
Do away with a great deal of the complicated framing of joints.
Make simpler the design of heavy construction.
Offer increased efficiency in the utilization of material.
Lessen the quantity of timber and hardware used.
Save your time and labor.
Another way to save time and make your woodwoking projects easier is to work from properly prepared plans. If you have a project in mind, click on the resource box below to check out the masses of downloadable plans available for almost any project you can imagine.
Source by Keith Wheeler