All about hole saws

In the ordinary minds of people, a saw is in any case something direct. The next logical association is a gasoline saw with chains and all similar equipment. But there is another species that the general audience doesn't know much about.

A hole saw for wood is called an end mill by some specialists. And this second name is quite justified. The similarity extends both to the appearance of the tool and to the course of material processing. Typical tooling, despite the significant volume of chips, ensures that the holes are as clean as possible. The standard hole saw blade for wood is made in the form of a cutting crown.

The number of teeth and their profiles are selected according to how strong and damp the tree will have to be sawed. Important: almost all manufacturers supply crowns as part of sets. Thanks to this, by changing the working part, it will be possible to process drywall sheets. Moreover, there are special crowns for working on metal. Regardless of this, the saw blade is divided into a working and a tail section.

For the processing of metal surfaces and products, carbide elements are recommended. Tail blocks are manufactured using structural (quenched) steels. To make them firmly connected to the cutting parts, a brass alloy of increased resistance is used. Often, the opposite face of the shank is equipped with seats for electric drill chucks.

With the help of a special spring, chips are removed from the inside of the circular saw. The main properties of circular saws are:

• the height of the working parts of the crowns (determining the depth of the tool penetration);
• outer section of the cutting segment of the crown;
• tooth profiles.

In most cases, the height of the working lobe of the crown is 4 cm. The hardness and saturation of wood with fibers differs - therefore, the real depth can reach 3.5-3.8 cm. We are talking about maximum indicators, more accurate information can be found only for each specific type of workpiece. As for the outer diameters, typical sets contain crowns with a cross section of 3-15 cm. When selecting this indicator, one should not forget about the restrictions imposed by the total power of the motors and the number of revolutions they give out.

All this significantly complicates the matter and increases production costs. It should be noted that some of the circular saws are made in a reversible manner. For craftsmen, this is a very useful acquisition (it will be possible to hold the drive with one or the other hand). But it should be borne in mind that after a long work, the tool, instead of cutting wood, will begin to rip off the top layer.

A characteristic feature of the device is strong heating during operation. Therefore, you will have to take fairly frequent breaks. Violation of this rule threatens to break the hole saw. The only way to get around this limitation is with a dedicated air cooling system.Practical characteristics directly depend on how exactly the parts of the typesetting saw are connected.

If the shank and the cutting block are joined by flat soldering, the tool is not designed for significant shear effects. It can only be used for a short time. A very small amount of material can be removed per pass. The diameter of the installed nozzles is limited to 3 cm. If you install a larger element, it is unlikely to work stably.

In addition to fixing the crown in the seat block, the use of a support shoulder is practiced here. They put it on top. This solution allows you to increase the caliber of the cutter to 150 mm and more. Some companies have even mastered the production of tools with a cross section of over 200 mm (up to 21 cm). With this size, the inevitable thermal expansion of the material will not damage the tool.

It is not always possible to compensate for the shear force due to the large size of the hole saw. In addition, even this solution, while reducing the thermal load, does not exclude the loss of accuracy. Special technical devices used in individual models help to cope with this problem. These include the use of centering pins to prevent crowns from going astray.

It is very good if the ejector spring is included in the delivery. It makes it easier to drill blind holes in fiber-rich wood. After all, it is impossible to exclude in advance that you will have to process a pear, ash or hornbeam. When it is planned to punch blind holes larger than 7-7.5 cm, saws with auxiliary threaded nozzles will perform very well. They are attached to the lower parts of the glasses with at least three screws. It is undesirable to use very large (larger than 4.5 cm) nozzles, otherwise the inertia will grow too much, and the drill will not cope.

Hole saws are considered more modern and practical, where, instead of hexagonal holders, SDS + format keyless chucks are used. To ensure efficient processing even of hard, thick wood for a long time, a drive with a power of at least 1000 W must be used. This should be taken into account when choosing the tool itself, because it must be compatible with such drills. Crowns 16.8 and 21 cm are mainly used in the industrial segment. The situation is practically excluded when such a device may be needed at home.

The teeth of hole saws for metal and wood do not differ externally. All the difference between them is related only to the chemical composition of the material. It should be borne in mind that such saws are designed for processing only thin sheet metal. Attempts to cut through thick items will get you nowhere. You can process:

• metal siding;
• metal tiles;
• profiled steel deck;
• sheet galvanized steel.

But even these materials cannot be drilled at high speeds. Otherwise, the hole saw will be broken very quickly and irrevocably. But a very low rate is also unacceptable - few people like to punch every metal sheet for hours. The conclusion is simple: you need to choose medium operating modes. Combination hole saws (for plastics and wood) are usually equipped with non-replaceable carbide teeth.

When holes are being prepared in wooden walls, most often they have to be finished with an electric jigsaw.Therefore, if aesthetic considerations are in the first place, it is better, instead of a saw, to immediately take a jigsaw. The diamond hole saw only helps punch through concrete and steel. If you try it on softer materials, the cutting performance will quickly be lost.

For how to work with a hole saw, see the next video.