The idea of converting an old one refrigeration compressor a jigsaw seems strange at first glance, but it has every right to live in the arsenal of a home craftsman. The main advantage of this solution lies in the enormous torque that the motor can develop even when removed from the refrigeration circuit. Unlike standard household jigsaws, which often suffer from low power when sawing hard wood or metal, a homemade unit based on a compressor is capable of coping with really serious loads.
However, the implementation of this project requires not only technical skills, but also a clear understanding of the principles of operation of AC electric motors. Asynchronous motor, used in refrigerators, is structurally different from commutator motors in conventional tools. This imposes certain restrictions on the ability to adjust the speed, but in return it gives incredible reliability and durability. You get a tool that is almost impossible to burn overload, and it will work for years without maintenance.
Before you start dismantling the components and welding the frame, you need to weigh all the pros and cons. Such a tool is not suitable for jewelry work, cutting out complex patterns on 3 mm thick plywood; its element is rough cutting, working with thick workpieces and materials where strength is needed, and not high cutting speed. If you are ready to sacrifice the ergonomics of a factory tool for the sake of unkillable power, then creating a jigsaw from a compressor will be an excellent experiment.
Design analysis and donor selection
The first step is always the search suitable compressor. Not all models are equally suitable for conversion. The best units are from Soviet refrigerators of the BK series or more modern analogues, where the engine has a pronounced cylindrical shape and is rigidly attached to the casing. It is important to understand that we need a serviceable motor that can start without the characteristic hum and vibration, indicating an interturn short circuit.
Particular attention should be paid to the type of starting equipment. Older models use a start relay and capacitor, which will need to be carefully integrated into the new control circuit. Modern compressors may have built-in electronics, which significantly complicates the task, since inverter motors they require specific frequency converters. For our project, classic single-phase motors with a starting winding are ideal.
⚠️ Attention: Before any dismantling work, make sure that the compressor is completely disconnected from the power supply and the refrigerant is safely released in a well-ventilated area. Residual pressure in the system can be dangerous.
When choosing a donor, also evaluate the condition of the shaft. It must be perfectly smooth, without traces of corrosion or wear, since it is to it that the rotation will be transmitted for conversion into reciprocating motion. If the shaft has play or damage, it is better not to start the project, since balancing the flywheel will be impossible.
Necessary materials and tools
To create a full-fledged machine or hand tool, you will need to assemble a certain set of components. The main consumable material is rolled metal for creating a frame or body. You can use a profile pipe, corner or thick plywood if you are planning a lightweight option. Metal is preferable, since vibrations from a working compressor will be significant.
The key element of the mechanical part will be the crank mechanism. You can make it yourself from steel or use ready-made solutions, for example, a connecting rod from a motorcycle or adapt parts from a car engine. You will also need a saw blade, which can be taken from a regular jigsaw or hacksaw for metal, having previously modified the shank.
- 🔧 Compressor from a refrigerator (power from 100 W).
- 🔩 Metal sheet or profile for the frame (thickness of at least 3 mm).
- ⚙️ Bearing units for the shaft (closed type).
- 🪚 Saw blades and clamping mechanism.
- 🔌 Starting relay and capacitor (if not on the compressor).
Don't forget about the fastening system files. Factory jigsaws use a complex pendulum mechanism, which in a homemade product is replaced with a simple rigid or hinged clamp. To implement a high-quality cut, you will need to create guides that prevent the blade from moving to the side. hardened steel or bronze bushings will help here.
Manufacturing a crank mechanism
The heart of your future jigsaw is the mechanism for converting shaft rotation into saw motion. The simplest and most reliable option is to use an eccentric. It is necessary to press a disk with an offset center onto the engine shaft or install a connecting rod with a pin located at a certain distance from the axis of rotation. This distance determines the stroke of the file..
The stroke of the file is a critical parameter. For a universal tool, a value in the range of 20–30 mm is considered optimal. A smaller stroke will not allow you to effectively remove chips from the cut, and a too large stroke will create excessive loads on the fastening points and can lead to breakage of thin blades. The calculation is made individually for each compressor, based on its power.
Stroke calculation formula: H = 2 * R_eccentricThe connecting rod is best made of duralumin or steel. Aluminum is preferred due to its lighter weight, which reduces inertial loads on the motor shaft bearings. A fork or collet clamp is installed at the bottom of the connecting rod to secure the saw blade. It is important to ensure the rigidity of the connection to prevent beating.
Why can’t you use a rigid rod?
Using a rigid rod without play at the bottom point can lead to jamming of the mechanism at dead points. Be sure to provide a hinge joint or an oval hole in the saw mount to compensate for horizontal displacements.
Assembling the frame and guides
The engine is mounted on a rigid base. If you are making a tabletop version, then the compressor is fixed under the tabletop with the shaft facing up. The tabletop is made of metal or textolite with a slot for the file to exit. It is important to ensure vibration isolation using rubber gaskets between the motor and the frame so that vibration is not transferred to the table and workpiece.
Guides for the saw are what distinguishes a professional tool from a homemade craft. They should be located as close as possible to the surface being treated, but not interfere with the view. The design can be made in the form of two rollers with grooves or graphite bushings. The gap is adjusted with screws, which allows you to work with files of different thicknesses.
| Parameter | Recommended value | Impact on work |
|---|---|---|
| Saw blade stroke | 20-30 mm | Cutting speed and chip removal |
| Stroke frequency | 800-1000 per min | Cleanliness of cut (depending on the material) |
| Power motor | from 150 W | Ability to saw hard rocks |
| Structure weight | from 5 kg | Stability during operation |
For the desktop version you will also need a presser foot. It prevents the material from lifting when the saw moves upward. Homemade designs often use a spring-loaded lever with a rubber roller that presses the workpiece against the table. This is especially important when working with thin sheets that can be torn out of your hands.
Electrical circuit and starting the engine
Connection refrigeration compressor requires knowledge of its electrical circuit. Typically there are three or four wires coming from the motor. Two of them are the working and starting windings, the third is common, and the fourth (sometimes) leads to a thermal relay. To start, you need to briefly apply voltage to the starting winding through a capacitor or use a special starting relay.
The safest and most convenient option is to use a ready-made starting unit from the refrigerator itself, if it is preserved. It automatically turns off the starting winding after gaining speed. If there is no relay, it can be assembled manually using a loose button and a capacitor. The capacitor capacitance is selected experimentally, usually within the range of 4–10 uF for engines of this power.
⚠️ Attention: Never leave the starting winding on all the time! This will lead to rapid overheating and engine combustion. The starting winding should work only at the moment of start-up (1-3 seconds).
To control the shaft rotation speed asynchronous motor a conventional dimmer is not suitable. You will need a frequency converter or a complex triac circuit with current feedback. However, given the specifics of a jigsaw, it is often enough to simply use a motor with a suitable standard rotation speed, since adjusting the speed of asynchronous motors is a labor-intensive task.
Testing and operational safety
The first start-up of the assembled device should be carried out without a saw blade. This will allow you to assess the level of vibration, shaft runout and engine heating. Check all threaded connections - they tend to unscrew spontaneously due to vibration. Use groovers or thread locker during assembly.
When working with homemade tools, remember the risks. Exposed moving parts of the crank mechanism pose a serious danger. Be sure to install a protective cover over the connecting rod and flywheel. The operator's hands must be at a safe distance from the cutting area, and the saw itself must be covered with a transparent polycarbonate screen.
- 🛡️ Install a protective cover on the crank mechanism.
- 🔌 Use an RCD in the power circuit to protect against electric shock.
- 🧤 Wear safety glasses, as pieces of the fabric may fly out.
- 🌡️ Monitor the temperature of the motor housing (no more than 60°C).
If you hear a strong hum during operation or the engine hums but does not develop speed, immediately turn off the power. This may indicate a malfunction of the starting system or jamming of the mechanism. Regularly lubricate the rubbing components, since industrial sealed bearings are rarely used in the design of a homemade jigsaw.
☑️ Check before first use
Frequently asked questions (FAQ)
Is it possible to adjust the rotation speed compressor?
Speed adjustment asynchronous motor is possible only with the help of a frequency converter, which is expensive and difficult to set up. Conventional voltage regulators (dimmers) reduce power and torque, which will cause the engine to stall under load. It is easier to choose a compressor with the required standard speed.
What files are best to use for such a jigsaw?
Standard files for jigsaws with a T-shaped shank are best suited, since they are easiest to clamp into a homemade fork. For metal, use bimetallic blades, and for wood - with set teeth. The length of the file is limited by the stroke of your connecting rod.
Is it necessary to change the oil in the compressor when remodeling?
Yes, this is critically important. Refrigerators use special refrigeration oil, which is not suitable for operation in open conditions and at other temperature conditions. It is recommended to completely drain the old oil, flush the system and fill in with high-quality motor or transmission oil that meets the operating conditions of the bearings.
Why does my jigsaw vibrate a lot?
Vibration is the main enemy of homemade structures based on compressors. The main reasons: flywheel/eccentric imbalance, lack of vibration mounts under the engine or play in the connecting rod connections. Try increasing the weight of the frame and using rubber dampers.