Homemade manual lever shears for metal. Lever scissors - how hard do they cut? Metal scissors drawing

Simple and easy-to-use scissors for cutting thin sheet metal easy to make in any workshop. They can cut strips of the same width without marking a cutting line, identical workpieces at right angles, and trim the flanges of squares to a given width. Performing these operations with simple metal scissors requires marking, takes a lot of time, and the cut line is not always smooth, especially if the workpiece is long.

The scissors frame is made of two squares with a cross-section of 75x75 mm, a length of 200 mm, fastened together with M6 screws.
Two identical knives 120 mm long are made from old flat files with a cross-section of 8x35 mm or from tool steel U7A or U8A.
The fixed knife is attached to the frame, the movable knife is attached to the lever with No. 6 screws.
Files should be annealed at a temperature of 750-800° to a dark cherry-red color and slowly cooled in air. Then cut to length and drill two holes in each of them for fastening. After the holes are drilled, a notch is ground on adjacent planes of the files. grindstone. Then the knives are heated to a temperature of 830-900° (to a light red color) and quickly cooled in water or mineral oil. To prevent them from warping during hardening, they should be lowered into water vertically. After hardening, the cutting edges of the knives are sharpened and tucked on a block. The lifting angle of the lever is adjusted with a limiter so that the planes of the knives do not come out of contact.

1 - base; 2 - screws securing the frame to the base: 3 - screws connecting the angles of the frame; 4 - screws for fastening Noshes; 5 - lever fastening nuts; 6 - washer; 7 - gasket; 8 - limiter screw; 9 - limiter; 10 - guide ruler; 11 - retractable bar; 12 - clamping screw of the strip; 13 - holes for screws for fastening the corner cover; 14 - guide ruler stopper; 15 - knives; 16 - bed angles; 17 - lever; 18 - screws for fastening the corner cover; 19 - corner pad for attaching the trimmed square.

The lever is made of steel 8-10 mm thick and 30 mm wide. It must be rigid enough to ensure that the working planes of the knives fit snugly against each other.
The frame is equipped with a guide ruler made of steel 6-8 mm thick. It moves in the grooves parallel to the plane of the knives.
The working planes of the ruler are cut or filed strictly under the ruler and square. The position of the ruler on the frame is fixed with two M6 wing stoppers. In the lower plane of the ruler, a groove is cut or milled at a right angle to the front edge, in which a retractable bar with a cross-section of 20x2 mm moves, allowing workpieces to be cut at an angle of 90°. The position of the bar is secured with an M5 clamping screw and washer.
To prevent the square from bending when cutting the shelf allowance using lever scissors, a removable pressure corner pad is made from sheet steel 0.8-1 mm thick. It has the cross section of a non-equilateral square. One shelf should be 1-1.2 mm less than the thickness of the guide ruler on which the square is installed; the other is 15 mm wide. IN larger shelf The corner trim and holes for the screws are sawn into elliptical shapes with a round file.
If, when cutting thin material, it bends, then the planes of the knives are poorly adjusted. If the width of the flange of the square being cut is not the same, the corner pad is installed with a large gap.
Depending on the quality of the knives, lever shears can cut sheet material up to 1 mm thick. It is not recommended to cut steel or other thick wire so that the blades of the scissors do not become jagged.
Finished scissors are painted oil paint, except for working planes, which are lubricated with machine oil.
The bed is attached to the work table with screws, bolts or a clamp. The scissors will be portable if they are mounted on a base made of a 30 mm thick board measuring 500x200 mm.

Among all types of separating equipment designed for cutting metal, lever shears are considered the simplest and most compact. They can be manually driven or driven by an electric motor. The versatility of this type of forging and stamping equipment makes it possible to install such shears in almost any household workshop, and even more so in small private enterprises working with long or sheet metal.

Operating principle and design features

Unlike sheet metal shears with an inclined knife (guillotine), the movement of the knife in lever shears most often occurs not along a translational path, but along a rotational path. In addition, the main actuator is not a crank-slider, but a lever.

Lever scissors, assembled according to the single-arm lever design, have become most widespread. When cutting thin metal, with a thickness of no more than 0.7...0.8 mm, hand-held shears are used, and when cutting thicker metal, chair scissors are used, the lever of which is much longer. In addition, the chair scissor designs provide for the possibility of integrating an intermediate gear transmission. This increases the length of the moving knife path, but reduces the resulting force, which is important if the unit is manually driven.

The largest versions of chair scissors allow cutting rolled steel sheets with a thickness of up to 8...10 mm, and long products with a diameter of no more than 22 mm.

Manually operated chair lever scissors are designed so that the driving arm is shaped like a saber. This makes it possible to bring the trajectory of movement closer to the operation of guillotine shears: the introduction of the moving part of the working tool into the metal being cut also occurs gradually. As a result, the current cutting force value is reduced. Non-powered (manual) chair-type scissors can cut steel up to 2…2.5 mm thick.

The typical design of desktop lever scissors is a combination of the following components:

beds;
eccentric or screw clamps, by means of which equipment can be permanently attached to a bench;
lower support frame on which the fixed part of the equipment is installed;
saber-shaped rotary lever with handle (for manual models). a movable part of the equipment is installed on it;
axles with plain bearings.

In addition to the above components, drive lever shears also have an electric motor, V-belt drive, as well as a crank mechanism, which converts the rotational movement of the engine shaft into the rocking movement of the lever. Sometimes such equipment is equipped with an activation mechanism (clutch and brake), and in this form they are not much different from stationary alligator-type scissors. Their only advantage in this case is the absence of a balancer to compensate for the inertia of massive parts.

Limitations of lever shears and how to overcome them

The main disadvantage of lever shears that do not have a mechanical drive is the need to make very long movements in order to reduce the force of cutting metal. In addition, with a manual drive it is impossible to ensure a constant cutting speed, which can deteriorate the quality of the metal cutting surface. By lengthening the drive, you have to sacrifice the overall dimensions of the equipment. In addition, lengthening the arm always worsens control over the quality of the workpiece clamp, and requires the use of more powerful clamps that hold the cut metal from moving. At the same time, there is also no possibility for high-quality cutting of profiled products: rods, angles, etc.

These limitations are overcome by designs with a multi-link cutting mechanism, as well as by the use of various methods of reinforcement without the participation of muscular force. In this case, a mechanical drive is not required.

Cutting Rules

In the first case, they are used mainly kinematic diagrams with two levers. An additional one is added to the main lever (each part of which is connected to the other part using a common axis), and its connection with the main pair is achieved by the presence of a cylindrical rod with a rack and pinion drive.

The rack and pinion mechanism consists of the following parts:

intermediate lever;
return springs;
swivel brackets;
a screw pair connecting the rail with the intermediate rod.

This method, although it provides higher quality metal cutting, but significantly complicates the design of lever shears. It is very difficult to make such an option at home; in addition, the worker’s effort will remain quite high.

If instead of a rack and pinion transmission a mechanical amplifier is placed in the intermediate rod, the resulting load will noticeably decrease. This type of manual lever scissors includes, in addition to the main working elements, also:

cylindrical hollow rod;
amplifier with self-braking thread;
connecting rod;
spring-loaded lock;
counterweight.

The presence of a load gives the metal cutting process an impact character, due to which it is possible to increase the cutting energy and separate workpieces with a larger thickness or area cross section. However, the shock nature of the load application tires the worker (especially during prolonged work), and the amplitude of vibration of the device on the frame increases. To install such scissors, you will need more reliable support and a flat floor surface. Metal cutting performance will also decrease.

The three-tier scheme is considered the most modern. In this case, the required compromise is achieved between the applied force and the length of movement of the movable tool.

Three-link lever shears

It has been established that the scheme, which will be described below, can cut long and sheet metal with a cross-sectional size of up to 10 mm, which in most cases is sufficient not only for one’s own needs, but also for the manufacture of steel products in a small business.

These scissors consist of the following components:

A frame, for the manufacture of which you will need two equal-sized corners with a shelf thickness of at least 7 mm.
The lower support to which the working tool is attached.
The upper support, which is installed in the seat, and has a bevel in order to reduce the gap between the knives at the moment the cutting begins.
The housings in which the mounting holes for the knives should be made slightly oval in shape to compensate for possible errors in the installation of the tool.
Earrings.
Connecting axis.
Fasteners.

For the manufacture of all parts of the multi-link mechanism, medium alloy steel grade 35 or higher will be required.

The length of the support frame is determined maximum dimensions metal to be cut: the size of hand scissors will be approximately twice the width of the workpiece. However, the design turns out to be quite compact, and allows you to use a regular bench vice and a workbench of appropriate size for installation.

The working tool attachment scheme is as follows. In the equipment made from high-strength tool steel grades U10 or U12, mounting holes are made with a countersunk conical part so that the fastening is flush-mounted. The kit should include options for cutting profiled metal. To facilitate maintenance, the equipment should be made double-sided. Next is produced heat treatment to a hardness of at least 54...56 HRC, and grinding in order to eliminate possible warping of the working blade. The finished equipment is installed in the lower and upper landing parts, and is adjusted one after the other in such a way that the actual gap between the moving and stationary parts does not exceed 5...8% of the thickness of the metal being cut.

Maintenance and operation

The main routine maintenance of the equipment consists of periodic sharpening of the tooling (during first use, simply turn the knives 180°). Sharpening can be done at sanding machine using a carborundum wheel, after which it is necessary to grind the resulting surface. After repeated regrinding, the stability of the gap must be maintained by installing steel gaskets. Their thickness is determined experimentally.

Cutting sheet material into pieces is carried out using various instruments. Roller shears for sheet metal cutting are popular, a trend due to their simple design and high productivity. The device is used in industrial and small workshop environments.

Characteristics of scissors

The purpose of roller knives is to cut steel sheet up to 1 mm thick. They are necessary at the site for the production of ventilation ducts, when working with roofing metal, during the construction of a fence and arrangement of the roof.

The mechanism is used to produce semi-finished products for subsequent bending of profiles for various purposes. The equipment is installed in car body repair shops. In auxiliary production, blanks are prepared for the assembly of racks and cabinets.

Scissors with rollers will successfully replace manual option or guillotine due to a number of advantages:

Compact dimensions and light weight.
Simple device.
Convenient to use.
Just getting set up.
Suitable for working with sheets of different materials: aluminum, tin, steel, roofing iron.

The processed product is obtained with clean cut in the absence of burrs and bends. It is easy to cut sheet metal with such a device.

Scissors can be purchased at a specialized store or made independently. It all depends on the volumes performed and the economic component. With a daily cutting rate of 30–50 meters or more, an industrial design will be required.

Description of scissors

The task of dividing a sheet of metal into parts is solved by destroying the strength bonds on a local segment.

The power part consists of two cutting roller discs with multidirectional rotation. Their cutting edges lie in the same plane. When rotating, the rollers are pressed into the surface and cutting occurs due to shear deformation. The sheet metal is fed to the tool by friction of the knives against the metal.

The design of the cutting mechanism includes two rotating rollers located one above the other. Depending on the design of the cutting part, roller knives distinguish:

With one inclined edge for straight longitudinal cutting and cutting out round and ring workpieces.
With parallel position of knives, cutting material in strips with high quality. They occur most often.
With several inclined edges for convenient cutting of curved, round and ring-shaped workpieces with a small radius.

All types of scissors provide cutting of sheet material with high quality, without the need for subsequent cleaning of the cut edge.

To increase productivity and obtain an even cut, the housing with roller knives is installed on a stationary machine.

The cutting equipment includes a bed with supporting surfaces, equipment for fixing the material and a roller knife. The latter contains a body made of steel gauge, an overhead handle, cutting rollers, and a mechanism for adjusting gaps in several planes.

Material for cutting discs serves as tool steel.

The manufacturer sets an average service life of 25 km to cut sheet metal with a thickness of 0.5 mm. With increasing thickness, the service life decreases proportionally. The cutting element is subject to regrinding, which significantly increases the service life.

How to make a roller knife

A purchased model of roller shears, even of the simplest design, is unprofitable for purchase in a small workshop or private household. It is not necessary to use it often, and the device is expensive. The optimal solution is making scissors with your own hands.

The design of the mechanism may be different, but the basis will always be cutting knife in the form of a roller. The selected material for making knives determines the performance of the device and the quality of the cut. Knives must be strong and reliable, with a surface hardness significantly greater than the hardness of the material being cut. Otherwise, you won’t get a high-quality cut; the edges will have to be processed additionally.

Homemade roller knives are made from bearings. To do this, the ends are sharpened to create a cutting edge. The drive roller is mounted on the handle. When working with it, the knife is pressed into the workpiece. The lower roller is installed permanently. During the cutting process, you need to press the handle with the roller with one hand and pull the sheet of metal with the other.

Selecting a larger bearing diameter will increase cutting speed.

For convenience and precise cutting, additional guides are installed.

Adjustment is carried out using oval holes, a set of spacers and special bolts.

If you are proficient in metalworking techniques, manufacturing a cutting device takes 7–10 days, including setup.

In a home workshop or small business for the manufacture of products from sheet metal Sheet metal shears, more simply - a guillotine - will never be superfluous. The driven version can be installed, for example, in a garage, and a manual guillotine will not take up much space at all. If there is enough large quantity manufacturing options (in drawings, videos or descriptions), as well as some adapted components from some decommissioned equipment, making homemade metal shears is an accessible reality.

The work of the simplest metal scissors

The principle of cutting with guillotine (sheet) shears is that the knife beam of the device, to which the movable part of the tool is attached, along the working end must have an angle of 1.5...3°, as a result of which metal cutting occurs non-simultaneously across the entire width. This reduces the cutting force, but requires a technique that would compensate for the shear of sheet metal (tin, thick cardboard, etc.) during cutting. Thus, a reliable clamp is required.

To drive a homemade guillotine, you can use a low-power electric motor, since the energy intensity of the process is low. But according to the results of calculating the maximum cutting force, it is often sufficient manual drive, For example, lever type(V homemade devices This is often what is suggested). You will also need reliable guidance of moving parts during the cutting process, as well as a rigid support surface for the bed. In this case, the parts of the homemade guillotine and the product itself will not be elastically deformed.

The drawings usually indicate the limits of the thickness and width of the sheet metal or tin for which the device is designed. If the entire process of obtaining sheet shears with your own hands is carried out independently, then the design begins with clarifying the power characteristics of cutting and choosing a mechanism diagram.

The initial data for choosing a design are:

the type of material with which operations will be performed;
maximum sheet dimensions in terms of thickness, length and width;
separation accuracy;
limit overall dimensions scissors;
drive type.

Mechanical guillotine shears

The manual device is the simplest in design. It includes:

support table on which the initial workpiece will be located;
two or four racks that will provide the scissors with strength and stability;
a rotary axis with plain bearings (rolling bearings are unsuitable, since the clearances during operation of such a guillotine will change significantly, which will quickly lead to jamming);
a knife beam, which provides seats for fastening replaceable knives;
fixed knives, which are mounted on the front end surface of the work table;
a rotating lever that will forcefully move the beam during cutting;
clamps for fixing metal.

Do-it-yourself production starts from the table. Its dimensions must be sufficient for convenient placement blanks, taking into account the places for fixing clamps: there must be at least two of them, on each side of the sheet. The thickness should prevent deflection under deformation forces. The easiest way is to use a steel plate, which you install on the channels yourself. The joints can be bolted flush with the top surface, or welding can be used. The front end must be ground to ensure evenness of the subsequent fit of the stationary knife to it.

The next stage is to obtain the support posts yourself. They must be made from a solid profile. Will fit square pipes made of high-quality medium-carbon steel, or channel. The cross-sectional size can be easily calculated from the maximum load on the racks, which is the sum of the self-weight of the components of manual guillotine shears for metal, and the cutting force P, kN.

The latter is calculated according to the dependence:
P = B∙s∙σ avg ∙k,
k – coefficient taking into account possible unevenness of the working gap, bluntness cutting edges, quality of the material being cut, etc. Typically k = 1.05…1.3;
IN - greatest width metal sheet, mm;
s – maximum metal thickness, mm;
σ ср – shear strength of the material, MPa.

For the most commonly used materials in everyday life this parameter is, MPa:

for low-carbon steel – 280…290;
for medium carbon steel – 300...400;
for high carbon and stainless steel – 400…500;
for sheet metal, aluminum – 65...80;
for copper, brass – 180…200.

When assembling the racks with your own hands, it is imperative to maintain the parallelism of the supporting surfaces and their perpendicularity to the axis of rotation of the knife beam. For these purposes it is better to use laser level. The floor where the scissors are installed must be made level and durable. Do-it-yourself installation of equipment on compacted soil, laminate and other options for coating concrete with polymers is not allowed.

A particularly important moment is making a knife beam with your own hands: its profile must be made such that during the turning process the movable knives gradually come into contact with the metal being cut. There are two options for this:

profiling along the contour of the saber, with a gradual increase in the radius of curvature as it approaches the lever handle;
pyramidal profile with a bevel angle of no more than 5...60 (at a larger angle, the metal will begin to deform and bend in the direction of the rotation axis).

The saber-shaped profile is more difficult to make, but it provides a smoother integration into the metal being cut.

For better direction of the body, it is placed either in a special groove on the table, or - with increased deformation forces - special guides are designed, which are attached to the racks with your own hands.

It is better to make the rotation axis from high-quality carbon steel, and then harden it to a hardness of at least 42...45 HRC. Bearing bushings are made of OF10-1 bronze, which has good wear resistance.

For the manufacture of tools, tool steels U10 or U12 are used, hardened to a hardness of 48...54 HRC. Hardened knives are carefully polished with your own hands, after which they are sharpened at an angle of 85...90°. The gap between the knives is taken within 3...6% of the thickness.

Lever metal shears are a popular tool that is used to perform various procedures for cutting materials - sheet metal, tin, profiles, wire. Although the market offers all sorts of hand tools of this type, there are often adventurers who prefer to make guillotine devices with their own hands.

Guillotine devices for cutting metal are based on the lever principle of operation;
The cutting process is carried out by a pair of cutting surfaces;
In this case, the length of a knife for metal can be about 20 centimeters;
One cutting surface is firmly fixed on the base of the machine and is subject to the full force of pressure during metal cutting;
The moving part is located on the bed, which facilitates high-precision cutting;
On a stationary blade, hand tools provide a special groove for the slide. It is designed to move the slider as needed. The groove carries out movements in one plane;
The moving part of the cutter is connected to the slider;
The working stroke of this slider is usually 15-30 millimeters;
The movable knife is firmly connected to the handle, the length of which is about 500 millimeters. Due to this, during the cutting process you can apply less force with your own hands in order to cut sheet metal of the required quality;
Guillotine devices have a metal body, which significantly extends the service life and increases the loads that the tool can handle when cutting sheet metal, profiles, and rods;
Cutting knives are made of high-strength tool steel. This allows you to cut sheet metal parts with minimal effort and without deformation of the cutting edges.

Using guillotine hand tools for cutting metal, you can process it yourself:

Sheets of steel up to 5 millimeters thick;
Products made of sheet aluminum up to 6 mm thick;
Brass 6 mm thick;
Metal profiles with a section of 6 by 80 mm;
Steel rod No. 13.

Species

To purchase manual cutting tools or make guillotine devices with your own hands, you will first need to become familiar with the types of these devices.

Structurally, lever scissors are almost no different from each other. Therefore, the main difference lies in the type of drive used. Hence the classification, dividing devices into three main categories.

Hand cutters. These are the most simple devices cutting applications that require you to manipulate the blade with your hands to get the job done.
Electrical. They are distinguished by high productivity and speed of work. To cut profiles, sheet metal, rods, you do not need to apply any physical effort.
Hydraulic. Most powerful species equipment whose operation depends on a hydraulic drive. Widely used in cutting the thickest and most durable materials. They are used extremely rarely in everyday life.

When choosing lever tools for cutting sheet metal, rods, profiles, you should pay attention to one more important parameter— length of the actuator. The capabilities of the scissors directly depend on the length of the blades.

There are three main types of scissors according to length:

Short. Are different small in size, allow for through cutting of material;
Long. These guillotine devices provide straight cutting, minimizing the effort and time required to process workpieces;
Combined. Can cut sheet metal, metal profiles, rods in different ways. Distinctive feature- ability to carry out contour cutting.

It is impossible to use lever scissors for processing small items. Their main purpose is cutting and cutting large workpieces and parts.

All factory lever shears on the market and homemade devices can be divided into two large groups:

Stationary. They are securely fixed on the desktop or workbench with special devices provided for by the design of the machine;
Portable. Also designed for fixing to work surface. But in this case, fastening is carried out with bolts or clamps. If necessary, they can be easily removed and moved to another area to perform the assigned tasks.

Hand scissors

Manual guillotine devices are the most often preferred choice for home use. Their simple drawings allow you to make simple desktop units with your own hands. They do an excellent job cutting thin sheet metal.

But before you choose these hand tools, you need to know what varieties they come in. Such knowledge allows you to make homemade metal scissors if you wish. Although desktop factory models do not cost much, they will not require you to make significant financial outlays to purchase a tool for use at home with your own hands.

Manual guillotine devices are divided into several types:

With a straight blade. These guillotine devices allow cutting sheet metal and other workpieces only in straight lines;
With curved blades. If you need to make sheet metal complex elements, make holes on the workpieces, it is recommended to choose just such devices;
Chairs. Useful thing for those who need to cut a thick layer of paper or a large stack of sheets at once. Saves time, requires relatively little physical effort;
Finger. Due to their thinnest incisors, these hand scissors are able to make the required neat holes;
Lever. These are desktop devices that need to be firmly fixed to a table or workbench.

Manual lever units are designed for through and straight cutting along straight lines. Often found in workshops, they are often used at home due to their capabilities and functionality.

Guillotine, lever, manual, electric, hydraulic types of scissors found wide application in the fields of metal processing.

Once you have lever shears at your disposal, you should familiarize yourself with the basic rules for using them. This will not only allow you to cut metal workpieces correctly, but also preserve own hands in integrity.

Wear strong protective gloves before you begin. This way you will protect yourself from sharp metal sheets. They themselves can cause injuries, unpleasant cuts, if you simply pick them up to place them on a cutting machine.
Securely secure your lever attachments according to the manufacturer's instructions. For different models scissors may have their own installation features on the desktop. Therefore, first of all, study the factory instruction manual.
Place the sheet of metal you are cutting perpendicular to the blades of your lever shears. Hold the base with your right or left hand, depending on whether you are right- or left-handed.
Gently and gradually press the handle of the scissors from top to bottom.
Remember to wear closed shoes to avoid being injured by falling metal scraps.
For a desktop, choose designs with a strong and stable base.

Working with lever shears for metal is not difficult, but it requires compliance with certain safety measures.