Varieties of lever scissors and recommendations for use

Selection principles

When choosing a working tool, it is necessary to pay attention to a number of factors, on which its capabilities will depend:

1. Drive power.
2. Lever size for hand scissors.
3. Blade material.
4. Dimensions of cutting parts.
5. Allowable thickness of processed metal sheets.
6. Equipment dimensions, weight.
7. Control type.

When choosing, you need to check the integrity of individual items of equipment, the presence of fasteners, the stability of the tool.

Advantages and disadvantages

Any instrument, both manual and electric, has a number of strengths and weaknesses. Advantages:

1. High precision of cuts.
2. Low energy consumption when working with electric shears.
3. You can cut workpieces of different thicknesses.
4. Compact dimensions of powerful equipment.

Disadvantages:

1. The impossibility of making curved cuts.
2. Thick sheets are deformed near the cut.

To process workpieces of different thicknesses, you need to purchase electrical or hydraulic models.

Manufacturers and cost

The price of the equipment depends on different criteria:

1. Maximum thickness of the cut metal.
2. Brand celebrity.
3. The dimensions of the blades, the material from which they are made.
4. Machine dimensions.

The following stand out from domestic manufacturers:

1. JET.
2. Blacksmith.
3. Proma.

Limitations of the lever scissors and the ability 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 separation surface. When lengthening the drive, you have to sacrifice the overall dimensions of the equipment. In addition, the lengthening of the shoulder always worsens the control over the quality of the workpiece clamping, and requires the use of more powerful clamps that hold the cut metal from displacement. At the same time, there is also no possibility for high-quality cutting of profile rolled products: bars, corners, etc.

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

Cutting rules

In the first case, mainly kinematic schemes with two levers are used. An additional one is added to the main lever (each of the parts of which is connected to another part using a common axis), and an additional one is added, 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;
• screw pair connecting the rail with the intermediate rod.

This method, although it provides a higher quality of metal cutting, significantly complicates the scheme of the lever scissors. It is very difficult to make such an option at home, in addition, the effort of the worker will remain quite high.

If, instead of a rack and pinion, a mechanical amplifier is placed in the intermediate rod, then 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 retainer;
• 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 to separate workpieces with a greater thickness or cross-sectional area. However, the shock nature of the load application makes the worker tired (especially during prolonged work), and the vibration amplitude 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 most modern is the three-link scheme.In this case, the required compromise is achieved between the applied force and the length of travel of the movable tool.

How to choose?

In order for the blank of sheet iron to really turn out to be of high quality, you need to understand the nuances of operating a particular cutting device. Metal workpieces are stiff. However, profiled and sheet products do not have to be processed with professional elements.

The approach to work related to metal processing is characterized by the use of hot or cold cutting. If the workpiece is cold worked, there is no structural change. A functional device for this work is selected with increased strength. It should be more durable than a regular blank.

With the hot processing method, the material is exposed to temperature. This work involves the use of machines of classic dimensions with autogenous. Household operation of such tools is impossible. But there are equipment options that are equipped with a laser for cutting, which also have a temperature effect.

It is better to choose household lever scissors with plastic attachments on the handles. Ribbed handles provide a more grippy grip. If the processing operation is critical, it is better to choose a tool equipped with an electric drive. The motors of such products are on average about 500 watts. The performance of the variants is high and the accuracy is better.

If metal workpieces are of increased hardness, it is better to choose machine equipment for processing them. The design of the equipment can easily handle workpieces of about 100 mm. In this case, the machine processes parts at an increased speed. A power tool will also save sheet material, since the consumption of chips will turn out to be small.

Usage Tips

Lever shears can be useful if you need to periodically cut sheet metal and cut wire. Their use is relevant in the presence of sheets with a thickness of over 0.5 mm. Among the masters, this tool is called power scissors, as they are "stronger" than ordinary ones.

For successful operations, the lever scissors must be properly secured to a serviceable surface. The steel base should be positioned strictly perpendicular to the cutting part. The movable part descends smoothly, without jerking. It is imperative to hold it by the handle.

The main advice for using the tool is to observe safety precautions. Even experienced locksmiths experience cuts on their fingers due to forgetting to wear protective gloves. Sheet metal, especially when cut, is usually very sharp. Therefore, if the leaf accidentally falls on its edge, it may even cut off the limbs. The work requires exceptional accuracy.

It is necessary to monitor the good condition of the scissors, as well as the health of the working table, which should not wobble, but be well fixed. The device itself must be kept clean, and work on a faulty device is completely prohibited.

Since the operation of the equipment carries risks, it is important for the craftsman to choose the right clothes, which should not be with bulging parts. Long sleeves, pockets, other parts can be pulled into the device

It is best to keep a distance from moving parts.

Do not use lever devices for unsuitable tasks. For example, for cutting wood or plastic surfaces.

For the best performance of parts, moving parts must be lubricated periodically. This will eliminate premature corrosion, and the scissor blades need to be sharpened periodically. When cleaning, do not use solvents or varnishes, as these substances damage the painted parts of the scissors.

If there are drive belts in the design of the machine, they require special attention, as they usually wear out quickly.Parts should be monitored for wear and tension and, if necessary, periodically renewed.

If the equipment is purchased for personal use, its adjustment, adjustment and maintenance are the sole responsibility of the buyer.

See below for an overview of the lever cutter.

Maintenance and operation

The main routine maintenance of the equipment consists in the periodic sharpening of the tooling (during the first operation, the knives can simply be turned 180 °). Sharpening can be carried out on a grinding machine using a carborundum wheel, after which it is necessary to grind the resulting surface. After repeated regrinds, the stability of the gap must be maintained by installing steel shims. Their thickness is established empirically.

The clearances in the joints are periodically checked and lubricated with Industrial-20 oil or similar.

It is strongly discouraged to dwell on the sector version, which will require welding, when making equipment. In this case, the accuracy of cutting metal will inevitably deteriorate.

To improve the reliability of mounting desktop manual scissors with a lever mechanism on a locksmith's workbench, it should be reinforced from the opposite side using a steel angle, channel or thick strip.

DIY making

If you want to place such a tool in your workshop, you can save money, make it yourself. To do this, you first need to find a drawing on the Internet. Next, you need to prepare tools, consumables for work:

1. Welding machine.
2. Electric drill with a set of drills for metal.
3. Grinder with discs.
4. Metal channels, corners, plate (about 4 mm), blades.
5. Bearings, arm tube, shaft.
6. Bolts, nuts.

Assembling a homemade machine:

1. Make a bed from metal corners.
2. Fasten the fixed knife to the metal plate with bolts. Reinforce it with a welding seam.
3. In one of the edges of the lower knife, where there is no sharpening, make a hole, fix the shaft with bearings in it.
4. Attach a movable knife to the shaft.
5. Weld up the lever to control the tool. The longer it is, the less effort will be required to separate the parts.
6. Additionally, you can install a vice, with which it will be possible to hold the parts while cutting.

Check how the knife moves. If difficulties arise, the design needs to be revised, sorted out.

Exploitation

For safe use, you need to learn the rules for working with the equipment:

1. Work using protective gloves, goggles.
2. Secure the workpiece with an additional vice so that it does not move during work.
3. Lubricate moving mechanisms with engine oil 1-2 times a month.
4. If metal chewing occurs on the electric shears, you need to disconnect them from the mains, try to pull out the material yourself, without turning on the electric motor.
5. Lower the lever smoothly, slow down towards the end of the cuts.
6. Keep your hand no closer than 10 cm from the sharp edge.
7. Check how securely the separable parts are held.
8. Start electric models with an additional pedal, keep your hands away from the blade.

The operating rules apply to both purchased and home-made machines.

Lever shears are used to separate various metal parts. Depending on how thick the workpiece needs to be divided, a tool drive must be selected. If you wish, you can assemble them yourself, use them to help during construction, home improvement, and plot.

Peculiarities

Lever shears are simple and compact products equipped with a manual or electric drive. The equipment is considered universal, but belongs to the forging and stamping type.Such scissors are placed in private workshops, used in enterprises that process high-quality iron.

The design features of the lever shears are hidden in the rotational direction of the cutting knife. There are also guillotine shears, the action of which is often progressive. The main servo drive of the lever scissors is a crank-slider element. Lever scissors for metal are subdivided into locksmith and chair.

Manual single-arm products are designed for cutting sheets of 0.7-0.8 mm, the second copies are usually longer, and also provide for the possibility of using an additional gear transmission. It affects the trajectory of the moving part, increasing it

However, more effort is required to work, which is especially important if the tool is equipped with a hand drive.

The length of the qualified blades is an important feature of the lever cutter. Depending on this parameter, there are three main types:

• short;
• long;
• combined.

The first ones are the smallest in size, so they can only perform through cutting of metal.

The second fixtures can provide cutting. In this case, a minimum amount of time is spent on processing.

Combined products can be used in various ways. This tool can cut sheets, profiles and rods, and you can also make contour cuts.

Views

Lever shears are not limited to types for cutting bulky sheet bases. Filigree work with the preparation of patterned edges and decoration can be done by hand, rather than table-top scissors for metal. The creation of parts with this device is not an easy job, and tabletop versions equipped with a double gear are unacceptable for shape cutting purposes.

The types of portable lever scissors are divided into:

• knife;
• carved.

The knife scissors are equipped with two single-edged knives. Cutting metal with the device is possible only along the edge of the sheet.

These products are conventionally subdivided into two more groups:

• along the incision (left / right);
• by the shape of the cut (rounded / straight).

Straight scissors can be used to prepare semi-finished products with straight edges. With curly products, you can get a beautifully crafted detail that can be used for decoration. Manual scissors for metal are more widespread than stationary ones, and they also come in several additional subspecies.

For example, there are modifications for roofing iron that attach to a locksmith's workbench. This allows the owner to spend less effort. The tool is compatible both with profiled metal of regular shape, and with shaped bases, which differ in complex shapes.

The die-cut tool works according to the gouging theory of the base to be cut. The products are suitable for processing profiled or corrugated iron. Blanks can be cut into any options.

Device and principle of operation

The principle of operation of the lever unit is simple, however, beginners will be interested to know what elements this tool consists of:

1. Cast frame, which ensures the stability of the shears when working with workpieces.
2. Clamping mechanisms that allow you to fix the structure on any surface, transfer them from place to place. This makes the cutting process easy.
3. Support frame. It is made of channels, corners.
4. Swing arm with handle.
5. The axles on which the plain bearings are mounted.

The working part of the tool deserves a separate consideration. It consists of two blades - movable and fixed. They must be made of high-strength metal in order to be able to cut different materials.

Three-bar lever shears

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

Such scissors consist of the following units:

1. Bed, for the manufacture of which you will need two equal corners with a shelf thickness of at least 7 mm.
2. The lower support to which the working tool is attached.
3. The upper support, which is installed in the seat, and has a bevel in order to reduce the gap between the knives at the time of the start of cutting.
4. Housings, the mounting holes for the knives in which it is worth making a slightly oval shape to compensate for possible errors in the installation of the tool.
5. Earrings.
6. Connecting axis.
7. Fasteners.

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

The length of the support frame is determined by the maximum dimensions of the cut metal: the size of the hand shears will be approximately twice the width of the workpiece. Nevertheless, the design turns out to be quite compact, and allows you to use ordinary locksmith's vice and a workbench of an appropriate size for its installation.

The fastening scheme of the working tool is as follows. In the tooling, made of high-strength tool steel of grades U10 or U12, bore holes with a countersunk conical part are made in order for the fastening to be flush-mounted. The kit should include options for cutting profile metal. To facilitate maintenance, the tooling should be made double-sided. Further, heat treatment is carried out to a hardness of at least 54 ... 56 HRC, and grinding in order to eliminate the possible warping of the working blade. The finished tooling is installed in the lower and upper seating parts, and fit one another in such a way that the actual gap between the movable and stationary parts does not exceed 5 ... 8% of the thickness of the cut metal.

Operating principle

The use of lever scissors is wide, especially common in plumbing. Cutting and notching metal, other than a tool, requires some skill. The sheet must be correctly positioned between the tip of the scissors

Correct pressure of the upper knife is important. Even the sharpness of the blade matters

For example, the harder the sheet, the better it should be sharpened. The taper angle should be calculated by the following parameters:

• for a soft sheet - 65 degrees;
• medium sheets - 70-75 degrees;
• hard sheets - 80-85 degrees.

The average size is 56 * 18 * 45 cm, and the weight is about 30 kg. The sharp edges not only of the scissors themselves, but also of the cut metal sheet, can cut. Therefore, it is imperative to use protective gloves when working. The principle of operation assumes:

• fixing the tool on the edge of the desktop;
• placing the base perpendicular to the blades;
• holding with one hand;
• smooth and precise pressing on the tool with a movement from top to bottom.

The described principle is one of the simplest hand cutters that you need to manipulate with your own hands. Less muscle tension is needed for an electric tool. The load in this type of scissors is carried by the electric motor. The accuracy of the cut is higher, and there are less distortions in the work.

Modern lever-operated shears, equipped with an electric motor, are powered both from the battery and from the mains. The scissors have a start lock against unintended activation. Among the battery and network options, the former are more often chosen for home use, and the latter for installation in workshops, at construction sites.

For large scale construction, a hydraulic lever cutter is the best option. The principle of the tool is similar to the previous versions. The difference lies in the voltage applied to the tip from the hydraulic cylinder or pump. The weight of such a tool of modern samples varies from 4 kg, and the pressure on the metal is about a ton. The scissors provide the best cutting quality.It is safer to work with the tool, and they have the best mobility.

Principle of operation and design features

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

The most widespread are lever scissors, assembled according to the single-arm lever scheme. When cutting thin metal, with a thickness of no more than 0.7 ... 0.8 mm, hand locksmith scissors are used, and for thicker ones - chair scissors, the lever of which is much longer. In addition, in the diagrams of chair scissors, the possibility of embedding an intermediate gear transmission is provided.

This increases the length of the trajectory of movement of the movable knife, but reduces the resulting force, which is important if the unit has a manual drive.

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

Hand operated chair arm scissors are designed so that the drive arm is in the shape of a saber. This makes it possible to bring the trajectory of movement closer to the work of guillotine shears: the introduction of the movable part of the working tool into the cut metal also occurs gradually. As a result, the current value of the cutting force decreases. Non-powered (manual) chair-type scissors can cut steel up to 2 ... 2.5 mm thick.

A typical design of table-top lever scissors is a combination of the following units:

1. bed;
2. eccentric or screw clamps, by means of which the equipment can be permanently attached to the locksmith's workbench;
3. the lower support frame, on which the fixed part of the equipment is installed;
4. saber swing arm with handle (for manual models). the movable part of the equipment is installed on it;
5. axles with plain bearing.

In the drive lever shears, in addition to the above units, there is also an electric motor, a V-belt transmission, as well as a crank mechanism that converts the rotational movement of the motor shaft into a swinging movement of the lever. Sometimes such equipment is equipped with an engaging 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 balance bar that compensates for the inertia of massive parts.