A cleco, also spelled generically cleko, is a temporary fastener developed by the Cleveland Pneumatic Tool Company. [1] Widely used in the manufacture and repair of aluminum-skinned aircraft, it is used to temporarily fasten sheets of material together, or to hold parts such as stiffeners, frames etc together, before they are permanently joined. [2]
Clecos are installed in holes drilled through the workpieces (usually holes intended for permanent fasteners installed later). They expand on the far side of the workpieces and then draw and clamp them together while maintaining the desired alignment and preventing distortion of the pieces. Clecos should fit snugly in their holes to prevent shifting of the workpieces and maintain the alignment of fastener holes which do not have Clecos in them. They are blind fasteners; so they can be installed in assemblies where the worker does not have access to the other side. If permanent fasteners are installed in Cleco holes, a Cleco will be removed when its hole is needed. If the workpieces are bonded or welded, then the Cleco holes may need to be filled later.
The basic type consists of a steel cylinder body, a plunger on the top, a spring, a pair of step-cut locks, and a spreader bar. A special type of pliers are used to push in the spring-loaded plunger. This pushes down on the step-cut locks, which pushes them away from the spreader bars and allows them to come together. This allows the user to slip the locking jaws through a hole made through multiple sheets of material. When the plunger is released the spring pulls the locking jaws back towards the spreader bar, which separates the two jaws. The material sheets are then squeezed in between the step-cut area and the steel cylinder. This keeps the holes in the separate sheets aligned. [3]
Cleco-type fasteners are also available with a threaded mechanism to draw the spreader bar up. Clecos of this type take more time to install and remove, but can pull parts together more tightly than the spring-type Clecos. They are commonly available with a wingnut for hand tightening, or with a simple hex nut so that they may be spaced more closely together. In either case they will usually have a hexagonal body that may be better gripped to tighten or release the spreader bar.
Regardless of their form, they are typically color-coded for ready identification of their size.
| Color | Size inches (mm) |
|---|---|
| Silver (zinc) | 3⁄32 (2.4) |
| Copper | 1⁄8 (3.2) |
| Black | 5⁄32 (4.0) |
| Gold (brass) | 3⁄16 (4.8) |
A screwdriver is a tool, manual or powered, used for turning screws. A typical simple screwdriver has a handle and a shaft, ending in a tip the user puts into the screw head before turning the handle. This form of the screwdriver has been replaced in many workplaces and homes with a more modern and versatile tool, a power drill, as they are quicker, easier, and can also drill holes. The shaft is usually made of tough steel to resist bending or twisting. The tip may be hardened to resist wear, treated with a dark tip coating for improved visual contrast between tip and screw—or ridged or treated for additional 'grip'. Handles are typically wood, metal, or plastic and usually hexagonal, square, or oval in cross-section to improve grip and prevent the tool from rolling when set down. Some manual screwdrivers have interchangeable tips that fit into a socket on the end of the shaft and are held in mechanically or magnetically. These often have a hollow handle that contains various types and sizes of tips, and a reversible ratchet action that allows multiple full turns without repositioning the tip or the user's hand.
Drill bits are cutting tools used in a drill to remove material to create holes, almost always of circular cross-section. Drill bits come in many sizes and shapes and can create different kinds of holes in many different materials. In order to create holes drill bits are usually attached to a drill, which powers them to cut through the workpiece, typically by rotation. The drill will grasp the upper end of a bit called the shank in the chuck.
A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the tail. On installation, the rivet is placed in a punched or drilled hole, and the tail is upset or bucked, so that it expands to about 1.5 times the original shaft diameter, holding the rivet in place. In other words, the pounding or pulling creates a new "head" on the tail end by smashing the "tail" material flatter, resulting in a rivet that is roughly a dumbbell shape. To distinguish between the two ends of the rivet, the original head is called the factory head and the deformed end is called the shop head or buck-tail.
A die is a specialized machine tool used in manufacturing industries to cut and/or form material to a desired shape or profile. Stamping dies are used with a press, as opposed to drawing dies and casting dies which are not. Like molds, dies are generally customized to the item they are used to create.
A fastener or fastening is a hardware device that mechanically joins or affixes two or more objects together. In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or dismantled without damaging the joining components. Welding is an example of creating permanent joints. Steel fasteners are usually made of stainless steel, carbon steel, or alloy steel.
A reamer is a type of rotary cutting tool used in metalworking. Precision reamers are designed to enlarge the size of a previously formed hole by a small amount but with a high degree of accuracy to leave smooth sides. There are also non-precision reamers which are used for more basic enlargement of holes or for removing burrs. The process of enlarging the hole is called reaming. There are many different types of reamer and they may be designed for use as a hand tool or in a machine tool, such as a milling machine or drill press.
Sheet metal is metal formed into thin, flat pieces, usually by an industrial process. Sheet metal is one of the fundamental forms used in metalworking, and it can be cut and bent into a variety of shapes.
A collet is a segmented sleeve, band or collar. One of the two radial surfaces of a collet is usually tapered and the other is cylindrical. The term collet commonly refers to a type of chuck that uses collets to hold either a workpiece or a tool but has other mechanical applications.
A countersink is a conical hole cut into a manufactured object, or the cutter used to cut such a hole. A common use is to allow the head of a countersunk bolt, screw or rivet, when placed in the hole, to sit flush with or below the surface of the surrounding material. A countersink may also be used to remove the burr left from a drilling or tapping operation thereby improving the finish of the product and removing any hazardous sharp edges.
A chuck is a specialized type of clamp used to hold an object with radial symmetry, especially a cylinder. In a drill, a mill and a transmission, a chuck holds the rotating tool; in a lathe, it holds the rotating workpiece.
A split pin, also known in the United States of America as a cotter pin or cotter key, is a metal fastener with two tines that are bent during installation, similar to a staple or rivet. Typically made of thick wire with a half-circular cross section, split pins come in multiple sizes and types.
A punch press is a type of machine press used to cut holes in material. It can be small and manually operated and hold one simple die set, or be very large, CNC operated, with a multi-station turret and hold a much larger and complex die set.
Safety wire or locking-wire is a type of positive locking device that prevents fasteners from falling out due to vibration and other forces. The presence of safety wiring may also serve to indicate that the fasteners have been properly tightened.
A lathe center, often shortened to center, is a tool that has been ground to a point to accurately position a workpiece on an axis. They usually have an included angle of 60°, but in heavy machining situations an angle of 75° is used.
A butt joint is a technique in which two pieces of material are joined by simply placing their ends together without any special shaping. The name "butt joint" comes from the way the material is joined. The butt joint is the simplest joint to make since it merely involves cutting the material to the appropriate length and butting them together. It is also the weakest because unless some form of reinforcement is used, it relies upon glue or welding alone to hold it together. Because the orientation of the material usually presents only one end to a long gluing or welding surface, the resulting joint is inherently weak.
A speed nut, aka sheet metal nut or Tinnerman nut, is a type of locknut with two sheet metal prongs that act as one thread. They are made from spring steel.
A swage nut or self-clinching nut is a type of nut or threaded insert that is used on sheet metal.
A screw and a bolt are similar types of fastener typically made of metal and characterized by a helical ridge, called a male thread. Screws and bolts are used to fasten materials by the engagement of the screw thread with a similar female thread in a matching part.
A plastic cord lock attaches to drawstrings and tightens without the use of knots. Cord locks allow mountaineers to fasten clothing and camping equipment quickly in cold conditions when the fingers are encased in heavy gloves. They consist generally of three parts: a barrel, a toggle (plunger), and a spring. Squeezed together, tension is released and the cord lock can move freely up and down the cords. Released, the tension is engaged and the cord lock stays in place. They come in many sizes and shapes to suit to any purpose, including plastic cord lock, mini size cord lock, no spring cord lock, with spring cord lock, with rim cord lock.
A spring pin is a mechanical fastener that secures the position of two or more parts of a machine relative to each other. Spring pins have a body diameter which is larger than the hole diameter, and a chamfer on either one or both ends to facilitate starting the pin into the hole. The spring action of the pin allows it to compress as it assumes the diameter of the hole. The force exerted by the pin against the hole wall retains it in the hole, therefore a spring pin is considered a self retaining fastener.