Wednesday, November 30, 2022

How to choose a saw according to the work to be done?

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When we are going to decide to buy a saw that is suitable for our purposes, we must take into account several factors that depend fundamentally on the material and the task to be carried out.

Every carpenter or expert in woodworking knows these factors perfectly, but the hobbyist, beginner or those who do not know what aspects to take into account, can be overwhelmed by the variety of saw models available in hardware stores, hypermarkets or stores. related.

Before considering a purchase, however, it is very important to be aware of the different elements that characterize a saw and be prepared for the great variety that a seller will offer us. To this end, in this article we can review an introduction to the saw to internalize some basic details that we should know.

What follows, therefore, is a small orientation guide based on the knowledge that we already have and structured in a series of questions that we must ask ourselves before buying this manual tool.

1) What kind of work am I going to do?

Resolving this issue is paramount, because there are various saws depending on the requirement that the work demands of the operator. This will be a first approximation to determine, therefore, the optimal length of the saw and the number of teeth per inch. The recommended in this case is:

  • High demand work: For a rough but effective cut, a saw long with large teeth will give better results, so the most robust saws of at least 7-8 DPI are suitable. Its length should be between 550 and 650 mm to obtain long and vigorous movements.
  • General work: we must choose saws with medium-sized teeth, arranged at a rate of 7-8 to 9-10 teeth per inch (DPP). The minimum length of the saw should be 450 to 550 mm to achieve powerful and thrusting movements.
  • Precision work: the saws with small size teeth from 9-10 to 15-16 DPP are the most suitable, for example, for a custom cut in a furniture repair. In precision work, the length of the saw is not a decisive factor.
  • Work on drywall or hard-to-reach places: the most suitable are saw hacksaw or a jigsaw, which can easily reach places that a tool electrical.

2) What type and direction of the cut do I want to make?

This question is also determinant not only of the number of teeth per inch, but also from teeth design. If we are to consider the type of cut first, the fundamental question is:

a) Am I going to make a cut perpendicular or parallel to the grain of the wood?

The requirements that a saw for a transverse cut, that is, one made across (or perpendicular to) the grain of the wood, they are not the same as for a cut made along (or parallel to) it. In both tasks, the number of teeth per inch and the shape of the teeth have a considerable effect on the effectiveness of the saw.

A crosscut saw (also known as “chopping saw”) has beveled teeth designed as a series of small knives to separate the fibers of the wood as it is cut. This type of tool it also has a large number of teeth per inch, usually over 10.

On the other hand, the longitudinal or parallel cut saw (also know as “spinning saw” or of “cut to the thread”) have less DPP, usually between 4 and 10, and their design is not beveled, which means that they work more like small chisels, scraping the wood instead of slicing it.

The following figure shows the tooth profiles of a saw cross-cut and another longitudinal cut.

teeth of a saw

Many manufacturers offer saws that can perform both types of cut and usually have between 8 and 12 teeth per inch.

The second big question we need to ask ourselves is:

b) Will I make a pull or push cut?

The way to cut a saw It has a big impact on your design. almost all tools made in the west cut by push, that is, in the start stroke of the tool. This action creates compression in the sheet. To compensate for this force that could cause the blade to buckle, two types of design are used: either the blades are made thicker, resulting in a wide notch, or a reinforcing rib is added (typically producing , rib saws) which can however reduce the depth of cut of the saw. Push cutting is the standard for boards, flooring lumber, and all types of general or high-intensity work.

Saw pull cutting

Saw pull cutting

The japanese saws, on the other hand, make the cut by traction, that is, on the return stroke of the tool. The action of pulling the blade from the wood automatically creates tension in the blade, thus allowing it to be much thinner than a push cut blade. A thinner blade, therefore, can produce a narrower notch and be much more suitable for precision work or work that requires a fine finish. It is worth saying that if we do works of carpentry fine, restoration, repair of musical instruments, old watches and delicate objects, for example, we must cut by traction and therefore, think about using Japanese saws, or cabinetmaker’s saws or those that can cut both ways.

If we now take into account the direction of the cut, it is important to note the following:

  • Straight cut: are indicated the universal saws, which can cut logs, manufactured boards and general wood.
  • Straight or curved interior cuts: As we already stated, a saw A hacksaw or jigsaw is ideal for cutting grooves across the grain of the wood and for working in hard-to-reach places.
  • Angle cuts: here we should use a saw of rib and support us with miter boxes to make a perfect cut at 45 degrees.

3) What kind of wood do I need to cut?

The nature of the wood notably influences the type of saw to choose, particularly in the number of teeth per inch, which will give an indication of the fineness with which it will cut the tool. When cutting softwood, it is possible for high TPI saws to clog due to the large amount of debris produced.

  • Therefore, for soft woods (for example, pine, spruce, birch) we must choose a saw with a low number of teeth per inch say, 4 to 6 TPI for a ring saw or 10 to 14 TPI for a chopping saw.
  • Hardwoods, such as oak, beech, or mahogany, produce finer scrap during cutting, so we have to choose saws with a higher number of teeth per inch, for example, 8 to 10 TPI for cuts parallel to the grain and 15 TPI or more for cross cutting. Let us further bear in mind that the greater the number of teeth per inch of a saw, the slower the cut.
  • On the other hand, if the wood is presented in large and thick boards, both solid wood and plywood, it is convenient to use a universal handsaw.
  • If, on the other hand, we have to work on moldings, skirting boards and other elements that require precision, a rib saw will be the right one.
  • Finally, if we deal with wood or wet and tanned wood, the ideal would be to use a saw long (500 to 550 mm) and not more than 7 DPI, in order to achieve a coarse cut.

4) Will the work to be done be short or extensive?

This question is useful to decide on the details of comfort and performance that we will obtain from our saw. It is convenient that we review, therefore, some or all of these characteristics:

a) Handle type

Both the shape and material of the handle are important considerations. There are three basic types of shape:

  • Gun: was the traditional open handle, today almost in disuse, except for the saws small in size, such as pointed ones or those designed for dovetails.
  • Closed: confers better resistance and better handling of the cut. It is the current standard and can be made of (traditional) wood or plastic.
  • Straight: used exclusively in saws very fine cut or Japanese saws.
Saw handle type

Saw handle type

The type of material with which the handle is made is a factor that impacts the comfort of use, depending on whether the work will be prolonged or simply for a short time. To this end, we will find mangoes of saw of the following materials:

  • Plastic: They are lighter and cheaper. They are not recommended for intense and/or prolonged work, although many users prefer those that are designed in such a way that they can be used, together with the blade, as heel squares.
  • Wood: They offer a more natural touch, which makes them more suitable for work of medium duration or intensity.
  • Ergonomics: They are generally made of bi-component plastic material that provide an optimal grip, as they prevent the hand from slipping and significantly reduce operator fatigue. Recommended for heavy or prolonged work.
  • Ergonomic screwed: some manufacturers offer saws whose handle is screwed to the blade by means of a patented mechanism (see figures below). In this way, the blade can be easily changed for another of the same series, but with a different size and/or number of teeth, which provides great versatility to the user.
Saw handle material

Saw handle material

b) Type of blade and teeth

Another quality to consider is whether or not the blade is coated. Although many blades are oxide coated to protect against scratches and rust, some users find that uncoated blades tend to work better, as there is nothing between the blade and the material, and no chance of the coating coming off. wear, provide much less friction and easier cutting. However, many manufacturers have already addressed these drawbacks, developing special lines of saws Provided with low friction coating.

The type of tooth is also an interesting detail. Generally, the teeth of saws They are offered with a hardening (tempered) treatment that allows them to keep them much sharper for longer. However, once the teeth become dull, they cannot be sharpened again and the saw must be discarded. On the other hand, there are also saws whose teeth can be sharpened several times, and although they cost much more than those with hardened teeth, they have a very long useful life.

As we have just seen, there are several considerations. However, once we solved all these questions, we are going to check that the correct decision by the saw that we actually need will be much easier and we will be able to make the purchase with much more confidence.

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