Compressor from a refrigerator

For high-quality and fast painting with airbrushes and spray guns, for many other jobs in a home workshop, a desktop mini-compressor that can be assembled from a refrigerator compressor unit is suitable. Moreover, it is not at all necessary to use a new unit: one with clogged pump valves will do just fine. The main thing is that the electric motor should be in working order. And it’s easy to check it even before disassembly — by measuring with an ohmmeter the resistances of the starting and working windings (5 and 20 Ohms respectively).

To extract the electric motor with the pump from the housing, it will be necessary to make two circular cuts at the ends of the housing. Then, by unscrewing four mounting bolts M6, pull out the stator from one side, and from the other — the rotor with the pump, mounted on a disc-shaped base.

To restore the operability of the valves, it is sufficient to wash them in gasoline or acetone (when assembling, their petals should be installed strictly in their original place). The pump’s operability is checked after assembly by rotating the motor rotor with the outlet tube closed.

The assembly of the unit (already without the housing) consists of connecting the motor stator to the pump base using four M6 bolts and distance tubes 40 mm long. By evenly tightening the bolts, we carefully center the stator so that the rotor can rotate freely.

Changing the lubrication system of the electric motor and pump bearings comes down to replacing the oil intake with a simple oiler. For its manufacture, a film box 2X8 mm is suitable, into the bottom of which a copper tube Ø 4 mm is soldered, with its other end soldered to a flange of appropriate dimensions. Before long work, the oiler must be refilled. Recommended oil grades are AC-8, DS-11 or any automotive motor oils with a viscosity of at least 8 cSt.

As an air receiver, it is convenient to use an empty cylinder from tourist gas stoves. After removing the valve, a tee is installed in its threaded hole to connect the pump outlet tube with the pressure gauge and the receiver outlet tube.

Since the pump is capable of creating pressure over 10 kg/cm², the required reduction is carried out by a simple spring valve that bleeds excess air into the atmosphere.

The compressor base is a rectangular steel frame used in the refrigerator to suspend the unit. In its central part, a duralumin angle 45X45 mm is fixed on two bolts, on which the compressor unit is mounted.

The front panel, bent from a duralumin plate 1.5 — 2.5 mm thick, is bolted to the base frame. It houses the contact terminals, the working winding switch and the start button. Through a hole in its front panel, the outlet tube is brought out.

A hose for supplying compressed air can be made by yourself from a polyvinyl chloride tube. For it to withstand air pressure, a metal braid removed from a shielded wire should be put on it. The ends of the braid are sealed with threads or copper wire. Such a hose is strong enough and at the same time soft and convenient to work with.

Two years of compressor operation have shown the reliability and efficiency of the design. The compressed air practically does not contain oil. However, over time, some amount of it condenses in the receiver, so it is advisable to install a plug in the lower part of the cylinder to drain the condensate. It is not recommended to carry out painting work in cold weather if the compressor itself is installed indoors. In this case, moisture will collect in the hose, which can get into the paint.

The installation’s capacity is sufficient not only for work with an airbrush: its pump will quickly inflate a bicycle tube, a ball, inflatable toys. And even a completely deflated Zhiguli tire will take no more than 10 minutes. For those who need a compressor for working with a paint sprayer, a more powerful version of several pump sections mounted on a common base can be recommended. They can be driven by a chain drive from one electric motor.

A. VOYNICH