The hacksaw (saw) on a tree is practically in any house. It is one of the most common tools. Already in childhood, anyone meets her. The question immediately arises how to sharpen a hacksaw on wood.
Hardened teeth hacksaws are not subject to sharpening.
In various operations with wooden products, a hacksaw is actively used. Over time, the cutting surface becomes blunt and the tree becomes harder to cut. Even a very simple sawing board requires a long time and considerable effort. In this case, there is no other way out how to sharpen a hacksaw on a tree.
Features of a hacksaw
The shape of the teeth of the saw for cutting wood.
The wood saw is a saw made in the form of a steel blade, one of the edges of which performs the function of cutting. A cutting element of any hacksaw is a series of teeth cut on the edge of the blade at a certain angle. In size distinguish large, medium and small teeth. They have the following parameters: large - cut in the amount of 3-6 pieces per 1 inch with a step of 4-8 mm; small - with a pitch of 2-2.5 mm; medium - with a pitch of 3-3.5 mm.
Depending on the purpose of the hacksaw, the shape of the teeth may be different. When sawing wood across the grain (cross-saw), the cutting elements should be in the form of an isosceles triangle with an apex angle of about 40º for soft wood and 50-60º for hard wood. The teeth in this case are arranged vertically. For sawing wood in the longitudinal direction, a hacksaw with inclined cutting elements (hacksaw) is used. The angle of deviation from the perpendicular is 10-20º. When sawing wood in both directions, you can use a hacksaw of a mixed type with an inclination of the cutting elements of not more than 10º.
To eliminate the effect of jamming of the blade during sawing, wiring is performed on the cutting edge. It is achieved by alternately tilting the teeth in different directions. The width of the wiring (the width of the hacksaw on the outer surface of the divorced teeth) should be 1.5–2 times the thickness of the steel sheet. All the teeth on the side edges sharpened one-sided. The sharpening angle is 60-75º. The top is pointed.Back to table of contents
The need to sharpen a hacksaw
Scheme sharpening transverse saw.
During operation of the hacksaw, the cutting edge of the blade is subject to wear. First, the pointed tip of the tooth is rounded. Secondly, the side cutting edges of the teeth become dull and partially lose their function. Wear may be even and manifest on all teeth, but local damage is possible, affecting only some of the teeth. In addition, the toothing parameters change over time. Some of them can increase the angle of inclination and thus inhibit sawing. More often, a reduction in the width of the wiring is observed, which leads to wedging of the web during sawing.
The moment when it is necessary to sharpen a hacksaw on a tree is determined in a practical way. First of all, sawing becomes a difficult process that requires great effort. It is difficult to cut wood perpendicularly. When sawing, the blade is difficult to hold along the line - it starts walking in different directions. Feels frequent jamming of the blade. An experienced worker can determine the wear of the cutting edge by changing the color of the teeth and the sound that occurs when sawing. All this suggests that it is time to sharpen the hacksaw.Back to table of contents
Hacking teeth wiring requirements
Wiring and a template to check the correctness of sawing: a - wiring; b - template: 1 - protrusion; 2 - Nut of the adjusting screw; 3 - Saw blade; 4 - Plate; 5 - Spring.
Hacksawing sets the overall width of the cutting part, determining the width of the cut. In turn, the wider the cut, the easier it is (without undue friction) moving the web during sawing, but this increases the labor intensity of sawing, due to the larger amount of wood sampling. On the basis of practical considerations, it has been established that the optimal width of the wiring should be 1.5–2 times the thickness of the hacksaw blade when sawing hard wood and 2-3 times for soft breeds. With a common web thickness of 1 mm, the wiring of the teeth in one direction should be 0.25-0.5 mm in the first case and 0.5-1 mm in the second.
The quality of the wiring significantly affects the cutting process. All the teeth should be alternately bent in different directions by an equal amount. If some of them are bent at a greater angle than others, they will impede the movement of the canvas and wear out faster. When reducing the width of the wiring, the width of the cut will not allow the fabric to move freely, which also complicates the cutting.
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Important: bending the teeth in the direction of their base is impossible, since this can lead to their destruction, the tooth is bent in its middle part.
So that the tooth does not break during wiring, do not bend it completely.
Before sharpening the cutting element it is necessary to check and correct the setting of the teeth. The quality of the wiring is checked visually and by measuring the width of the wiring.
Breeding teeth hacksaw produced using a special tool - wiring. Elementary wiring is a small metal plate with a handle. A slit is made in the plate, with a width slightly greater than the thickness of the hacksaw blade. To improve the quality of breeding, use a wiring with a stop, which is set at the desired distance with the help of a wing nut and screw and thus controls the amount of bending.
The teeth themselves are diluted in the following sequence. The saw is clamped in a vice, so that only the teeth are above the jaws of the vice. They are alternately captured into the slot wiring and bent in the middle part at a given angle in the right direction. When using wiring with an emphasis, the teeth are first bent in one direction. Then the emphasis is rearranged, and the other group is bent in the opposite direction. Bending of the tooth is a smooth movement.
The quality of the wiring of the teeth is checked visually and by measuring with a caliper. To verify the absence of excessive bending of individual elements, a simple test is recommended. The saw after wiring is stretched between the jaws of the vice, which are separated by a width equal to the width of the wiring. Excessive bending of the tooth will not allow to move the canvas.Back to table of contents
Alignment height links
If the teeth of the hacksaw have different heights, then when sawing, they perceive the load unevenly. This increases the wear of higher elements and reduces the functional capacity of the hacksaw, since the low teeth do not practically participate in the cutting process.
Check and straighten the height of the cutting elements, it is advisable to sharpen a hacksaw. The easiest way to check is as follows. The saw is pressed tightly against a sheet of paper laid on a flat, smooth surface. The profile is imprinted on the paper, and a visible arrangement appears, over which the tooth sizes can be compared. If the teeth are detected with an increased height compared to the others, the saw is clamped in a vice, and they are shortened with a flat file.Back to table of contents
General requirements for sharpening
For sharpening longitudinal saw teeth, files or rhombic files are used.
The sharpening of a hacksaw is made using a tool that allows you to securely fix the saw at an angle of 45 and 90º to the table surface. The device itself should be well secured to the desktop. The workplace requires good lighting.
We can recommend the following design homemade device. On a wooden base with a size of 20x55 cm and a thickness of at least 20 mm, two right-angled triangles (with an angle of 45 °) of metal strip (for example, 20x3 mm) are fixed. A supporting wooden plate with a size of 15x40 cm and a thickness of at least 15 mm is installed on the triangles. A clamping wooden plate of the same size joins the bottom plate through the hinges. The fixing of the support plate while clamping the saw is done with the help of bolts with sheep. When the angle is set at 45º, the base plate is attached to the inclined strip of the triangle, and when the angle is set at 90º, it is attached to the vertical one.
As sharpening used files of different shapes and with different notches. Files should have a clear relief notches. When sharpening the movement of the file should be smooth. Metal removal is performed when moving the file only from itself.Back to table of contents
Sharpening teeth for wood saws
Diagram of the device for sharpening the saw.
When sharpening the teeth, the hacksaw blade is fastened between the plates of the device so that the teeth protrude above the plate to a height of 15-20 mm. The sharpening rules for different types of saws are different.
When sharpening a crosscut saw, the blade is set at an angle of 45º. Sharpening is done with a three-sided file with a peak angle of 60º. The file is sent to the tooth at an angle of 60-75º. First, the left edges of the distant teeth (odd ones) are sharpened with a few file movements. Then the hacksaw is turned over, and the left sides of the even cutting elements are sharpened. Sharpening should produce sharp side edges and a sharp tip.
When sharpening a longitudinal hacksaw for wood or a hacksaw of a mixed type, the blade is mounted vertically. In this case, it is recommended to use a file of rhombic type with a small notch or file. File is sent parallel to the table. The sharpening process is similar to sharpening a transverse saw.
On the edges of the teeth, the reverse sharpened, there are burrs that need to be removed with a file with a velvet notch or emery bar. The quality of sharpening is checked by touch and color. Good sharpened edges do not shine with light.Back to table of contents
For sharpening a wood saw, special attention should be paid to the preparation of files. The following file types are required:
- rhombic and flat with a middle notch;
- triangular with velvet notch;
- files with a small and large notch.
In addition, you must prepare:
- emery block;
- emery sandpaper;
A hacksaw can serve for a long time and efficiently, if it is timely to decide how to sharpen. The process of sharpening saws is not complicated, but requires accuracy and care.