The origins of chisel they date back to the days of primitive man, who used crude hand tools made of stone. Later, with the arrival of the age of metals, the chisels they evolved into pieces of copper, bronze or gold and once iron was discovered they were built with this material.
History records applications of the chisel in the carving of stone, bone, leather and other rigid animal material, wood and metal. However, the materials used until then in the chisels they were malleable and therefore did not possess the hardness required to do the job without deforming. Only when wrought iron began to be used, at the advent of the Christian Era, the chisel acquired the necessary robustness to evolve into today’s tools, built mainly in tempered steel, a much harder and non-deformable material.
The chisel It is only used cold with the help of a support tool as a hammer or one mace and its general functions are two:
to. split a material
b. Extract chips from a material
Based on these two functions, a variety of applications emerge, ranging, among others, from the opening holes and gutters in walls and breaking cement and concrete to the slot cutting, profiling, roughing, planing, grooving, carving and finishing parts. Therefore, the use of chisel extends to a multiplicity of areas, from the construction until the goldsmith, and the shape of the tool varies according to those applications.
However, although there are a variety of models, basically a chisel consists of four parts:
1. The head, which is the end that receives the impact of the support tool.
2. The mango, stem or body, through which this impact spreads.
3. The cradle, formed by the lateral parts where the cutting areas meet.
4. The cutting edge, which delivers the impact to the workpiece.
Thus, depending on the application, the design of the chisel can be in the form of bar, of rectangular, hexagonal, square or round section, sharpened at one end and chamfered at the opposite end. The materials that can be worked with a chisel span masonry, stone, marble, granite, metal and also wood, although wood chisels are known as chisels or chisels and therefore we will not address them in this article.
How the chisel works and choosing the right type
The diversity of models chisel It raises the question of which tool to choose according to the application and the material used. Therefore, the characteristics of the parts described in the figure above are of great importance at the time of decision.
To begin with, the mango of chisel It should be long enough to hold in your hand. If this were not the case, the head of the tool would be just above the hand, which could cause injury. The chisels Too long they tend to flex, are difficult to maneuver and break easily, so it is important to find a balance in the dimensions of the handle.
The application that we are going to give to the chisel is related to the position in which we will use the tool. If it is kept in a 90 degree angle relative to the surface of the workpiece, the chisel fulfills the function of separation of the piece into two halves (Figure 1). If it stays in a angle less than 90 degrees, then fulfills the function of chip removal (Figure 2).
The size of the support tool that hits the chisel and the speed at which it strikes determine the energy of motion that does the work of separation. It is important, therefore, that there is a ratio between the mass of the chisel and the mass of support tool and the ideal is that the latter is at least twice that of the chisel.
In turn, the cutting areas formed by the cradle of a chisel They are the ones that determine the cutting angle or edge, which is decisive for the effect of separation of the tool. Thus, the smaller the cutting angle, the tool will have a greater penetration and spreading effect on the workpiece, while large cutting angles will have a small spreading effect, as shown in Figure 3.
The material hardness must also be taken into account in the selection of the chisel suitable for separation. So, for example, if you work with metals, soft materials like aluminum will need a chisel with a small cutting angle, while hard materials, such as steel, will require a tool with a larger cutting angle.
Finally, how long should the cutting edge adequate? This will depend on the work piece thickness. If we have very thick sections, it is convenient to choose a chisel with a small cutting edge, since it has better penetration (Figure 4). If, on the other hand, we must section, for example, thin sheets, a chisel with a long cutting edge will save us a great deal of time.
types of chisels
The chisel most common is the one with the end flat and smooth, like the one in Figure 1, used extensively in both masonry and metal applications. If the cutting edge is extremely thin and sharp, the tool is called a chiller or iron cutters and is particularly used for opening small holes as well as cutting bricks and tiles.
For the mechanical parts In particular, other types of chisel, for example:
one. Cold chisel or iron chisel: For chiselling flat surfaces and cutting thin sheets and rods.
two. sharp pointed chisel: For grooving thin sheets and making small keyways and notches.
3. round nose chisel: to start holes to drill or carve grooves and grooves.
Four. Chisel for oil grooves: used to make lubrication channels in bearings and small grooves.
5. diamond point chisel: to cut “V” grooves and chisel corners.
In the works in goldsmith and jewelry are used chisels more specialized, such as:
Embossing chisel: Gives relief to different parts of the design, creating a three-dimensional effect.
flat chisel: with a flat and smooth tip, it allows flattening the surfaces to distinguish them from those with relief. Textured, rather than smooth, tips give rise to chisels known as money.
scribe chisel: Allows you to outline the main parts of a design by making a fine incision along the drawing on the metal.
opener chisel: widens the profile made by the tracer chisel.
textured chisel: it is used for the final finish to give greater naturalness or effects to the different forms of the design.
Precautions for handling chisels
The chisel must be handled with great care, ensuring that the support tool (hammer or mallet) does not slip off the end of the chisel and injure the operator’s hand. The hands and face should be protected with gloves and safety goggles to absorb shock and particle impact. If necessary, an annular protection of rubber sponge will be placed on the head of the chisel.
It should be noted that repeated hammering ends up flattening the head of chisel, which takes on a mushroom shape. When this happens, a grind will return the tool to its original shape, as shown in the following image. It is very dangerous to use chisels with flattened heads because of the projections of metallic particles that can be produced by the force of a bullet.
Advances in technology have made available a whole range of chisels for masonry and masonry that changes the concept we have of the traditional use of this tool. The chipping hammers are electric machines similar to a rotary hammer, capable of admitting a variety of chisels built in SDS-steel, in various ways of cradle designed for each particular need, as shown below:
one. cement chisel: to remove and clean joints in masonry and cement
two. tile chisel: to lift or remove tiles
3. fin chisel: for mortising and drilling channels and grooves with a depth limit
Four. serrated chisel: to sanitize masonry and joints
5. Carbide joint chisel: to remove and clean joints and masonry, with an extra long life
6. hollow chisel: for making small channels in masonry and concrete
7.Cribbed incel: to gouge and practice grooves and channels
8. spade chisel: for the demolition of large amounts of material
9. flat chisel: for selective cutting and all chiseling, demolition and breaching work
10 and 11. Pointing chisel: for laying ducts and all chiseling, demolition and breaching jobs.
The following video shows one of the multiple applications of this type of tool.