Hole saws
A hole saw for cutting metal works in conjunction with a hand drill or drilling machine and functions as a grinder.
Bimetallic hole saws have many varieties: they have different diameters, as well as different elements for metal processing: a knife, a drill, etc.
Hole saws are of two types: bimetallic and carbide models can be found.
Hole saw is a versatile tool. Bimetallic tools are necessary for sawing holes, suitable for working with wood, plastic, drywall, ferrous and non-ferrous metals.
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The bimetallic blades, from which the tools are made, are welded onto a strip made of spring steel.
The saw teeth are re-milled. Bimetallic tools have lower vibration and shock loading compared to other models due to the 4/6 variable tooth pitch.
Such ring bimetallic models have a long service life, since the cutting edge of the tool teeth is equipped with elements of high-quality high-speed steel.
Bimetallic saws are equipped with special cutting parts (this can be a knife, drill, etc.) that are capable of processing materials such as concrete, ceramics and other materials with high abrasiveness.
Bimetallic tools are often used in construction work, in this case, a special carbide knife and other cutting elements are used to process the material.
If the hole saw has a thin blade, then such devices are used only for processing wood.
There are also carbide hole saws.
They differ in characteristics that bimetallic models do not have.
This hole saw is used for drilling holes in more difficult materials: these tools are suitable for working with bricks, tiles, laminate, composites, etc., that is, materials that have abrasive and other difficult-to-cut properties. Video:
The teeth of such saws are made from carbide plates, which, after manufacturing, are soldered into the blade. The correct shape of the teeth is given using a grinding machine.
The teeth are made in increments of 4, so this type of hole saw is suitable for such difficult materials.
To work with metal, an annular bimetallic, or an assembly saw or a grinder is most often used.
In general, today there is a huge selection of saws designed for working with metal, which can be used both in professional construction and in private repair work.
You can make repairs with your own hands using any saw, the main thing is to understand what functions this or that model performs and choose a tool in accordance with them.
Concrete saw HRS from HYCON
The rigging at work with concrete also has its own characteristics. They are clearly expressed in the saw design introduced to the economic market by HYCON. It's complicated hole saw, but a hydraulic ring cutter, which is also used in the formation of holes in reinforced concrete, brick and stone slabs. Such a high technical and operational ability is justified by the fact that diamond spraying is used as part of the nozzles. By its features, this saw belongs to a special sector even within the industrial sphere. Suffice it to say that only a specially trained team can operate the rig. To ensure safety, the hole saw in the HRS modification is supplemented with an automatic shutdown.This function is triggered when it gets stuck in a solid niche, which also happens with the use of units of this type.
Articulating hole saw: diamond version
A diamond hole saw could be called versatile if it really handled all kinds of materials. But this is not the case - it is designed exclusively for cutting steel and concrete. Wood, drywall and many other soft materials clog the edges of diamonds, as a result of which they lose their ability to cut even metal with concrete - a paradox, but the same thing happens when diamond core bits are used to cut holes in asbestos, slate and aerated concrete. Diamond core bits are sold in stores in sets - exactly the same as hole saws for wood and drywall. That is, a large washer with a drill in the middle (the drill in such crowns has a victorious soldering) and about seven or eight interchangeable hole saws.
Hole saw set photo
In work, the diamond hole saw also has some features.
- First of all, these are all the same average revolutions - a high rotational speed of the hole saw leads to rapid wear of the diamond edge. To be more precise, it is better to cut with such crowns at low speeds.
- The second point concerns working with concrete. A diamond does its job better if the surface to be cut is moistened with water. For metal, this moment is not relevant.
- Often times, diamond-cut bits are used to drill holes in ceramic tiles - by and large, this is the only normal tool with which you can arrange neat round holes in tiles. When working with this material, it is necessary to take into account its fragility - so that the tile is not split, it must be drilled from both sides. First, from the front side, and then, when the enamel is cut through, it is necessary to go to the wrong side.
By and large, when cutting each material with a diamond hole saw, there are subtleties and nuances. For example, if we talk about concrete, or rather about reinforced concrete, then here we can note such a moment that, with proper cutting, the reinforcement of such structures for the saw is not a problem. It passes easily if you increase the speed a little and stop using water during the drilling process. As soon as the reinforcement is passed, it will be possible to add water again to the work process.
And in conclusion of the topic of what a hole saw is, there is only one thing to add - an infinitely deep hole cannot be drilled with this tool. As a rule, the drilling depth is limited by the length of the bit, which is the disadvantage of this tool - it is not intended for equipment through holes in walls
If you need to punch through a thick wall, then it is better to turn your attention towards the tubular drill.
The author of the article is Alexander Kulikov
List of sources
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- stroisovety.org
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Varieties
Hole saws are often used for tough materials. For example, a bimetallic hole saw can easily drill not only wood or drywall, but also non-ferrous metals and even steel workpieces. This saw is constructed from high quality hardened high speed steel and flexible carbon steel.
A hole saw with a carbide tip is used to cut round holes in tiles, stone, cement slabs and similar materials. This saw is often used when installing tiles around water faucets and pipes.
Carbide-tipped hole saws such as Bahco Carbide (CT) are used to create clean, precise holes in difficult to cut and abrasive materials. It will be used to work with foam concrete, brick, ceramic tiles, laminate, plywood, reinforced plastic, composites and other abrasive non-metallic materials.
The ring saw for wood is intended for use as attachments for hand or electric drills. It allows, without special preparation, to create a hole in diameter from 60 to 95 mm in wood, chipboard, fiberboard. This saw is made of hardened steel. Has side slots for quick removal of sawdust.
Homemade metal saws
It is also possible to make a band saw for metal with your own hands. A homemade device has its own advantages and disadvantages.
The advantages of such a device include the low cost of manufacturing and using the created tool.
The process of creating a tape apparatus includes several stages. First you need to make a frame that will hold the entire structure on itself. It can be made of any material, but, in terms of cost, the cheapest option is a wooden frame.
The next part of the tool is the upper pulley block, which, when moved vertically, will provide tension on the blade.
The saw table is mainly made of plywood. For more convenient use, the table can be rotated.
Blades and sharpening of the device
There are several types of saw blades for making a saw at home:
- Bimetallic blade, which is mainly used for cutting very strong metals and alloys.
- Diamond is used for processing granite, quartz, marble, and other hard materials.
- For small workshops that work with fragile materials, a tool steel blade is best suited.
So that the made tool does not become blunt and always be a faithful assistant to the master, it must be properly prepared for work. Sharpening band saws for metal is one of the most important stages of working with a tool. Depending on the teeth, wheels of different materials and different shapes are used for sharpening.
In order for the sharpening to be of high quality, it is necessary to carry out the procedure on the front surface of the tooth or using the back and front surfaces at once.
Carefully considering the choice of the tool, as well as with its correct use and timely sharpening, the device will serve its owner for a long time.
Types of bimetal band saws
Bimetallic metal saws are divided into three main types: for cutting carbon and low-carbon steels, for cutting high-carbon steels and alloys, for cutting heat-resistant, heat-resistant, wear-resistant and "exotic" alloys.
The first type is a universal high performance band saw with a cutting edge with teeth made of tool steel (designated as HSS) with a content of 10% molybdenum, 8% cobalt and a hardness of 68 HRCe, which makes it possible to use the saw for cutting structural and medium alloy steels with a hardness index of up to 45 HRCe.
High wear resistance of the cutting edge is achieved by adding cobalt to the alloy, and the accuracy and cleanliness of the cut are ensured by the unique technology of extremely accurate tooth setting.
They are used for cutting workpieces from a wide range of materials - from stainless steels to structural steels.
The second type is a special band saw with a cutting edge also made of tool steel (HSS), but not M42, but M51 (10% tungsten and cobalt each), due to which it has higher wear resistance and productivity. The index of the hardness of the teeth is 69 HRCe. Therefore, these saws are capable of cutting both special stainless steel and tool and high-alloy steel.
However, the saws of the second type are contraindicated for cutting thin-walled profiles and pipes, since its fragile teeth do not tolerate shock loads very well.
Therefore, the saws of the second type have only two forms of teeth:
- standard with a rake angle of 10 degrees for cutting thick-walled products and solid round billets of small and medium diameters;
- standard with a rake angle of 10 degrees and a hardened back of the tooth - used in mass production for cutting solid workpieces with a diameter of medium and above.
The third type is also a special band saw, which features an optimized tooth geometry and a specially developed backing material that provides this type of saw with the longest service life and high cutting accuracy. They are made with teeth of only one shape - with a rake angle of 10 degrees and a reinforced tooth back. By the combination of these features, the use of saws of the third type is most beneficial when cutting blanks from nickel and chromium alloys, as well as from "exotic" alloys like Hastelloy, Nimonic or Inconel.