Glues, Screws and Hardware for Home Maintenance DIY Projects

 

Glues and Adhesives

It’s not always possible to rely on glue alone to hold pieces of wood together, especially if the parts are in large sections or you’re working with something substantial such as a cabinet or bed frame.

Nevertheless, glues, adhesives, and cements have their place in all kinds of wood construction, and can often be used alone or with the mechanical fasteners described further on in this section.

There are differences among the three kinds of bonding agents other than their names. Good old-fashioned glue is made from natural materials — animal by-products that have certain advantages over the newer ingredients used for the most part today. One of these, liquid hide glue, remains popular because it fills gaps easily, has a high initial tack, and has good strength characteristics as long as moisture isn’t present. The other, casein glue, is processed from milk curd and mixed with water in the shop. It, like the liquid hide, dries slowly, so it’s good for projects that take time to assemble. Unlike the hide glue, though, it’s water resistant so can be used in more applications.

Glues, Screws and Hardware Adhesives are made from synthetics. The best all-around wood adhesive is aliphatic resin, a creamy yellow goo that comes already mixed in a bottle and is often referred to as “carpenters’ glue.” A variant of that is Type II adhesive, which is waterproof and specifically made for outdoor projects. Both these materials set up in 10 minutes or less, which means you have to work quickly with them. By the same token, their clamp time — the moments spent under pressure — can be as little as 60 minutes, though full-strength hardening takes about 24 hours.

Another adhesive often used for veneers and overlays, or when laminating (gluing together in layers), is urea formaldehyde, which comes as a powder then mixed with water, or in liquid form to which a dry powder hardener is added. It can be left open, or undamped, for up to 30 minutes, but needs to stay under pressure for 6 to 12 hours while curing.

Cements are made from rubber suspended in a liquid vehicle.

Contact cement is the most well known, and mainly used for holding veneers and plastic laminates in place on a wooden surface. It’s spread with a brush or roller on both surfaces and allowed to dry, then clamped precisely in place. Full curing occurs in a matter of hours, but the water-resistant bond takes place on contact.

It’s worth taking the time to read the label on the product you’re planning to use. Look for the set-up, or “open,” time, for this will tell you how many minutes you have available to fiddle with fit and placement before the glue begins to set. The clamp time mentioned previously also affects your work because you’ll want to know how long you’ll need to keep your clamps in place before they can be used elsewhere. Be aware that curing time can be affected by temperature, which speeds up the drying process; most agents require ambient temperatures to be over 65 or 70 degrees Fahrenheit in order to bond properly. To be on the safe side, glue joints should be allowed to dry 24 hours before attempting to cut or rout them.

For the best glue joint, the stock should be joined as soon as possible after it’s cut, and the parts should fit well together, without showing any large gaps. Grease, oil, and wax diminish the strength of a joint, so the wood surfaces need to be free of any film from saw blades or finishes. A slightly rough surface makes for a good bond.

When clamping, do not over-tighten the joint because it will force adhesive from the union. This will weaken the bond and probably cause some leakage which can stain the wood or pose a problem in finishing. Any excess adhesive should be wiped immediately from the outside surface of the wood with a damp cloth (contact cement can be removed with solvent, but it tends to “string” rather than run, so it’s not really a problem to work with).

 

Screws and Fasteners

Glues, Screws and Hardware Fasteners are used to join wooden parts and attach hardware such as knobs and hinges. They include nails, brads, screws, and lag bolts.

Nails vary in length and thickness. As the nail increases in length, so does its diameter. Penny sizes — indicated by the letter “d”  —  are a traditional unit of English measurement based on weight, which has evolved today into a standard based on length. Hence, all nails of a particular penny size are the same length, but the diameters vary from one type of nail to another. Penny sizes range from 2d (1″) to 60d (6″) in length.

Casing and finish nails have set heads designed to hold the wood from beneath the surface, allowing the hole to be covered if needed. The casing nail is similar to a finish nail, but with a more conical-shaped head to allow it to grip the wood with more effect. Both these nails are driven the last blow or two with a nail set, or a pointed punch described further in the section on tools. They can be used to secure panels and trim on most furnture projects.

Brads, or wire nails, are smaller and most often used to hold strips and trim. These finer nails have diameters measured by wire gauge, ranging from a 19g to 12g. In “gauge talk,” the higher number indicates a thinner nail, a 19-gauge brad having only a .042″ diameter. Brads and wire nails are measured by actual length in inches rather than by the penny size.

Wood screws come in a variety of styles, finishes, and materials, but only a few need to be mentioned here. Flathead Phillips-drive screws or the popular taper-headed cabinet screws are common and easy to work with. Some are pointed and coated for self-boring and others are designed with tiny cutting edges to countersink themselves. Square-drive screws with four-sided drive sockets can be bought in lots, but you’ll need a special — and fortunately not costly — drive bit to install and remove them. These are positive-grip heads that won’t slip even under tough conditions.

The traditional slotted flathead screw has almost been replaced by these newer styles, but maybe for good reason. They don’t hold a screwdriver blade well and for the most part must be hand-driven. Save them for those special occasions when you need that old-fashioned look.

Wood screws are sized by gauge number, which indicates their diameter in inches at the body, just below the head. They come in lengths from 3/8″ to 3-1/2″, though extended lengths of up to 6″ are available for special purposes. For example, a No. 8 x 1-1/2″ screw is one that’s 5/32″ in diameter and 1-1/2″ long (see the chart below for a full range of dimensions).

A screw’s thread design is worth considering, though it’s not necessarily a critical factor. Manufacturers may offer screws made with a fine pitch (or less distance between the threads)  —  to secure hardwoods  —  or a coarse one to grip softwoods.

Standard wood screws will usually work with particleboard and fiberboard, but straight-shank (non tapered) screws with widely spaced threads and a narrow core diameter have been specially developed for these manufactured sheet materials.

Lag screws are large-diameter square or hex-head steel fasteners with shank sizes from 1/4″ to 1/2″. Lengths range from 1″ – 6″ or 8″. These are largely decorative, or used when a screw larger than No 12 is needed. For more positive holding power, a machine screw or carriage bolt is a better choice because it uses a nut and washer to secure the joint from both sides.

Finally, there are the odds-and-ends fasteners for specific purposes: screw hooks, cup hangers, shoulder hooks, and screw eyes. These are usually brass plated and under 3″ in length, with diameters measured in the wire-gauge scale. For heavier jobs, longer, bright-plated hooks and hangers are available. Shoulder hooks and cup hangers have a shoulder or stop where the threads meet the shank.

 

Hardware

Hardware includes the miscellaneous metal fixtures used in finishing a project — hinges, brackets, latches, drawer slides, handles, and knobs (even wooden ones).

Hinge hardware can be a bit confusing because of the terminology. Butt hinge is the generic term for the two-leaf square or rectangular fixture joined in the middle by knuckles that pivot on a pin. More recently, the concealed hinge — a European-style piece of hardware that mounts from the inside — has been replacing the butt hinge, especially on cabinets that don’t use face frames or wide borders around the doors.

Glues, Screws and Hardware It’s important, however, to look a bit further. There is a full-mortise hinge (made to be set into recesses, or mortises, cut into the surface of the wood); a half-mortise hinge (one leaf is mortised into the door and the other is simply screwed to the jamb surface); a full-surface hinge (both hinge leaves are fixed to the surface); and a half-surface hinge (one leaf is attached to the door’s surface and the other is mortised into the jamb).

And the European hinges offer other choices to think about: Because they use extended arms in addition to simple knuckles, they can be designed to swing clear of an opening, or open up to 270° for unobstructed access. They can also be self-closing.

The design of the project makes a difference too. With a cabinet, the doors can be full overlay, where they completely cover the face edge of a cabinet’s side or carcase; half overlay, in which two doors share and cover a common jamb (as in the middle of a row of cabinets); or inset, where the door is recessed into the cabinet carcase to create a flush surface, and the cabinet’s face edge is exposed.

It’s also common to have 3/4″ thick doors that are lipped at the perimeter by incorporating a 3/8″ x 3/8″ rabbet, or relief, into the back edges. These doors use hinges with leaves that are bent at multiple right angles to conform to the relief in the wood. These hinges are usually described as inset because the butt or “hanging” leaf is bent to the inside; offset hinges are those in which the leaves are formed away from the center of the pin.

Brackets are used to help support shelves and reinforce corners. In the days when furniture construction used wood almost exclusively, corner braces — made of triangular blocks of wood —provided this support. Today, it’s quicker and easier to let shaped metal do the job.

Corner braces come in a variety of styles — in metal and nylon — to secure corners from the inside. Corner plates, in the shape of an “L,” hold corners from the edge of the wood or on a flush surface when pieces are perpendicular.

Latches and catches can be mechanical or magnetic. Externally mounted turn catches and bolts are obvious in that they hook or slip into a socket or retainer mounted on the framework. Internal catches are usually smaller, less conspicuous, and often quite clever in their function. Besides the common bullet and double-roller or spring catch, there are touch-latch types that release when the door is pressed in, and flush-mounted ring-pull styles that unlatch by lifting a central ring.

Drawer slides are ready-made tracks that fit between the cabinet carcase and the sides of the drawers themselves. The rail section mounts to the cabinet and the slide arm fastens to the drawer. Nylon or steel ball bearings allow the arm to glide in and out.

Most small or lightweight drawers don’t need slides at all, because they can be fit loosely enough to function without binding. But when a drawer gets heavy, or wide and awkward, it needs positive guidance. The two things most important in selecting drawer slides are length (they can’t be any longer in closed position than the drawer itself) and weight capacity (a 25 to 150–pound range is common).

Handles and knobs are a matter of design and cost, unless they’re part of the latch. Most knobs and pulls are surface-mounted from the front, or blind-mounted from the rear using screws passed through holes in the door and drawer faces.

 

07. December 2010 by admin
Categories: Hand Tools, Home Maintenance, Woodworking | Tags: , , , , | Comments Off on Glues, Screws and Hardware for Home Maintenance DIY Projects

Follow

Get every new post delivered to your Inbox

Join other followers: