Checking, repairing and replacing the anchor of the grinder with your own hands

The anchor of the grinder is subjected to the most thermal, mechanical and electromagnetic loads. Therefore, it is a common cause of failure of the tool, and as a result, often in need of repair. How to check the anchor for performance and fix the element with your own hands - in our article.

The device anchors grinders

The anchor of the engine of the grinder is a conductive winding and a magnetic conductor into which the rotation shaft is pressed. It has a pinion gear at one end and a lamella collector at the other. The magnetic core consists of grooves and soft plates coated with varnish for isolation from each other.

Anchor patternScheme anchors grinders

In the grooves according to a special scheme laid on the two conductors of the anchor winding. Each conductor is half a coil, the ends of which are connected in pairs on the lamellae. The beginning of the first turn and the end of the last are in the same slot, so they are closed on one lamella.

Collector lamellaeCollector lamellae

How to check the anchor of the grinder for serviceability

Types of anchor faults:

  1. Open conductor break.
  2. Interturn closure.

  3. The breakdown of insulation by mass is the closure of the winding on the metal casing of the rotor. Occurs due to the destruction of the insulation.
  4. Wiring collector pins.
  5. Uneven wear collector.

If the anchor is defective, the engine overheats, the winding insulation is melted, the turns short-circuited. The contacts connecting the armature winding to the collector plates are sealed off. The current supply stops and the motor stops working.

Types of anchor diagnostics:

  • visually;
  • multimeter;
  • light bulb;
  • special devices.

Standard diagnostics

Before taking the device for diagnostics, inspect the anchor. It can be damaged. If the wiring has melted, the burnt insulating varnish will leave black marks or a peculiar smell. You can see bent and crumpled coils or conductive particles, such as solder residues. These particles cause a short circuit between the turns. Lamellas have curved edges, called cockerels, for connecting with the winding.

Cockerel LamellaCockerel Lamella

Due to the violation of these contacts, the lamellas burn out.

Burnout slatsBurnout slats

Other damage to the collector: raised, worn or burnt plates. Between the lamellae graphite from brushes may accumulate, which also indicates a short circuit.

Bent collector platesBent collector plates

How to check with a multimeter

  • Set the resistance to 200 ohms. Connect the gauges of the device with two adjacent lamellas. If the resistance is the same between all adjacent plates, then the winding is OK. If the resistance is less than 1 ohm and is very close to zero, there is a short circuit between the turns. If the resistance is above the average two or more times, then there is a break in the winding turns. Sometimes at a break, the resistance is so high that the device rolls over. On an analog multimeter, the arrow will go all the way to the right. And on the digital will not show anything.
    Diagnostics winding multimeterDiagnostics of armature winding with multimeter
  • Determination of breakdown on the mass is done in the absence of winding breakage. Put on the scale of the instrument maximum resistance. Depending on the tester, it can be from 2 MΩ to 200 MΩ. Connect one probe to the shaft and the other to each plate in turn. In the absence of faults, the resistance should be zero. Do the same with the rotor.Connect one probe to the iron body of the rotor, and the other move along the lamellae.

Video: how is the test

If you do not have a tester, use a light bulb with a voltage of 12 volts up to 40 watts.

How to check the rotor of the grinder with a light bulb

  • Take two wires and connect them to the lamp.
  • On the negative wire, make a break.
  • Apply voltage to the wires. Attach the ends of the gap to the collector plates and roll it. If the light is on without changing the brightness, then there is no short circuit.
  • Carry out a short circuit test on the iron. Connect one wire to the lamellae, and the other to the rotor iron. Then with the shaft. If the light is on, then there is a breakdown to the mass. The winding closes the rotor housing or shaft.

This procedure is similar to a multimeter diagnosis.

Check indicator short-circuited coils (ICZ)

There are anchors, which do not see the wires connected to the collector due to pouring with an opaque compound or because of a bandage. Therefore, it is difficult to determine the commutation on the collector relative to the slots. The indicator of short-circuited turns will help.

IKZ in the caseIKZ in the case

This device is small and easy to operate.

IKZ deviceIKZ device

First check the anchor for no breaks.Otherwise, the indicator will not be able to detect a short circuit. For this tester measure the resistance between two adjacent lamellas. If the resistance exceeds the average at least twice, then there is a break. If there is no break, go to the next step.

The resistance regulator allows you to select the sensitivity of the device. He has two light bulbs: red and green. Adjust the knob so that the red light starts to burn. On the body of the indicator there are two sensors in the form of white dots, located at a distance of 3 centimeters from each other. Attach the gauge to the winding. Slowly twist the anchor. If the red light comes on, then there is a short circuit.

Video: IKZ in work

Diagnostics device checking anchors (choke)

The tool for checking the anchors determines the presence of the interturn winding closure. A choke is a transformer, which has only the primary winding and cut a magnetic gap in the core.

Anchor CheckoutAnchor Checkout

When we put the rotor in this gap, its winding begins to work as the secondary winding of the transformer.Turn on the instrument and anchor a metal plate, such as a metal ruler or hacksaw blade. If there is an interturn closure, the plate will vibrate or magnetize to the armature body from a local iron overload. Turn the anchor around the axis, moving the plate so that it lies on different turns. If there is no closure, the plate will move freely along the rotor.

PPYAAnchor Tester

Video: How to make a choke with your own hands and check the anchor

How to repair anchor at home

Because of the anchor, a third of the screwdriver breakdown occurs. In the case of an everyday intensive work regime, malfunctions can arise already in the first six months, for example, when the brushes are not timely replaced. When used sparingly, the screwdriver will last a year or more.

Anchor can be saved, if not disturbed balancing. If an intermittent rumble is heard during the operation of the device and a strong vibration occurs, then this is a violation of the balancing. Such an anchor is subject to replacement. And you can repair the winding and the collector. Small short circuits are eliminated. If a significant portion of the winding is damaged, it can be rewound.Worn and badly damaged lamellas, grind, build up or solder. In addition, it is not necessary to undertake anchor repair, if you are unsure of your capabilities. It is better to replace it or take it to the workshop.

Groove collector

Over time, the reservoir is formed from the development of brushes. To get rid of it, you must:

  • To protrude the collector, using incisors for longitudinal grinding, that is, through cutters.
    Straight cutter straight throughStraight cutter straight through
  • We also need a reverse cone to center on the bearing. Make a hole in it to 8 mm.
    Reverse coneReverse cone
  • Since copper is coarse, adjust the machine to a speed between 600 and 1500 per minute.
  • Primary feed by half division. When the cutter touches the product slightly, make a longitudinal groove of the entire collector. By the resulting brilliant pattern, you will see the state of the slats, all surface irregularities.
  • If the collector is flat, the groove will be uniform.
  • If there are holes, continue the groove until the surface is level.
  • For the last pass you need to submit a cutter for one-fourth of the division.
  • For polishing, take sandpaper with a thousandth of grit and turn on the machine so that the anchor rotates in the direction it rotates during operation.

Do not forget to clean the rotor of chips, to avoid a short circuit.

Related videos

How to rewind the anchor

Before disassembling the anchor, write down or draw the direction of the winding. It can be left or right. To determine it correctly, look at the end of the anchor from the side of the collector. Put on gloves, take sharp nippers or a hacksaw for metal. Remove the frontal winding. The collector needs to be cleaned and not necessary to remove. Gently, without damaging the grooves, knock out the rods of the remaining parts of the winding with a hammer and a metal chisel.

Video: Remove the winding

With a needle file, without damaging the insulator film, remove the remaining impregnation. Count the conductors in the groove. Calculate the number of turns in the section and measure the diameter of the wire. Draw a diagram. Cut cardboard sleeves for insulation and insert them into the grooves.

Video: Winding left and right

After winding, weld the conclusions of the sections with the cockerels. Now check the winding with a tester and a short circuit indicator. Proceed to the impregnation.

Instructions for impregnation (taking into account the speed regulator)

  • Making sure there are no problems, send the anchor in the electric oven for warming up for a better flow of epoxy.
  • After warming, place the anchor on the table at an incline for better spreading through the wires. Drop resin on the frontal part and slowly twist the anchor. Drip until glue appears on the opposite frontal part.
    Tilt impregnationTilt impregnation
  • Place the anchor horizontally and drip onto both frontal parts. Twist the anchor before losing any fluidity.
  • Leave upright until fully cured.
    Air drying anchorsAir drying of anchor before polymerization

At the end of the process lightly grind the collector. Balance the anchor with dynamic balancer and grinder. Now puncture finally on the bearing. You need to clean the grooves between the slats and polish the collector. Make a final break and short circuit test.

The feature of the winding for Bulgarians with adjustable speed is that the rotor is wound with a power reserve. The current density affects the speed. The cross section of the wire is too high, and the number of turns is underestimated.

Repair: Breakdown insulation

If the breakdown of the insulation was small and you found it, you need to clean up this place from carbon and check the resistance. If its value is normal, insulate the wires with asbestos.From above drip quick-drying glue of the type "Super-moment". It will seep through the asbestos and well insulate the wire.

If you have not found the place of breakdown of the insulation, then try to gently soak the winding with an impregnating electrical insulating varnish. The punctured and impenetrable insulation will be impregnated with this varnish and become stronger. Dry the anchor in a gas oven at about 150 degrees. If this does not help, try rewinding the winding or changing the anchor.

Solder collector plates

Slats are mounted on a plastic base. They can be erased to the very core. There are only edges to which the brush does not reach.

Erased slatsErased slats

Such a collector can be restored by soldering.

  • From the copper tube or plate, cut the required number of lamellas in size.
  • After you have cleaned the anchor from the remaining copper, solder with ordinary tin with soldering acid.
  • When all the lamellae are soldered, sand and polish. If there is no lathe, use a drill or screwdriver. Insert the armature shaft into the chuck. First sand the file. Then polish with zero sandpaper.Do not forget to clean the grooves between the slats and measure the resistance.
  • There are not completely damaged lamellae. To restore them, it is necessary to conduct a more thorough preparation. Lightly grind the collector to clean the plates.
    Damaged collector plateDamaged collector plate
  • Place the space under the plate carefully with a drill, so as not to remove a large layer of insulator.
    Expanding space drillExpanding space drill
  • Find two pieces of copper wire of such a size that they fit snugly into the groove. Put the cleaned wires into the groove and strip.
  • Make a sipe of copper. It should fit tightly into the groove and be taller than the existing lamellae to make it easier to solder.
    Slot preparation in the grooveSlot preparation in the groove
  • Float the workpiece so that there is a lot of solder. She will sit more tightly in the groove. Lay the workpiece in the groove and attach a soldering iron to it. Hold it until the solder melts.
    Soldered blankSoldered blank
  • Excess unnecessary file, polish and polish.

If the collector has been worn out completely, then after soldering it will be enough for no more than a month of active use. And not fully damaged plates after such repairs withstand several brush replacements and are not evaporated.

Galvanic build-up of collector plates

The recovered copper is very hard.The service life of the collector is like new. Electroplating can be restored as a completely erased collector, and partially damaged plates.

Fully worn sewerFully worn sewer

The quality of recovery will be the same.

Damaged individual platesDamaged individual plates
  • Well strip the entire surface of the collector, including the insulator between the lamellae.
  • Wind bare copper wire with a diameter of about 0.2 millimeter.
  • Wrap the shaft of the anchor with adhesive tape, and smear the collector from the end with clay so that the copper does not grow where it is not necessary. And to iron did not get electrolyte.
  • For the bath, cut the floor of the plastic bottle. Wind electrical tape on the shaft so that it fits tightly in the neck of the bottle. Insert the anchor into the bottle.
  • Take a piece of copper bus. Its size is twice the stackable surface. Coil it and place in a bottle.
  • Connect the power supply minus to the surface being restored, and a plus to the tavern. One and a half amperes of current per square decimeter of solution. If the collector is separated from the shaft, wind it with wire and hang it in a jar on some crossbar so that the electrolyte touches only the worn part of the lamellae.Connect a series of bulbs of different power in series to regulate the amperage and prevent a short circuit on the vessel. After 24 hours, a reconstructed collector is obtained.
    Remanufactured collector prior to treatmentRemanufactured collector prior to treatment
  • The collector must be machined and the plates separated by a drill or hacksaw blade. At the end, test the collector for the absence of closures between the plates.
    Finalization of the collectorFinalization of the collector

Components of the electrolyte:

  1. Copper sulphate - 200 g
  2. Sulfuric acid 1.84 - 40 g
  3. Alcohol - 5 g. It can be replaced with a threefold amount of vodka.
  4. Boiled water - 800 ml.

How to change the old gearbox to a new one

Bulgarians differ in size, power, manufacturers, but the principle of the layout of components is the same. The new anchor of the engine of the Bulgarian is selected strictly in accordance with the model of your tool.

  • After unscrewing all fastening bolts of the casing, housing and gearbox, remove the gearbox with an anchor from the housing. Usually the gearbox and anchor are rigidly attached to each other. To disconnect them it is necessary to disassemble the gearbox.
    Reducer with an armatureReducer with an armature
  • Remove the mounting bolts.
  • The rotor shaft is bolted to the gearbox housing with a nut. Unscrew it.Remove the gear.
  • Next, there is a bearing. To remove it, sometimes it is enough to knock a wooden bar along the gearbox body. But most often stuck bearing can not be removed without some tricks. There is a plate between the impeller and the bearing, which is bolted to the reducer by two bolts. To get to them, break off a piece of plastic impeller or burn two symmetrical holes with a heated nail. The second hole is necessary for balancing, if you are not going to change the impeller.
  • Unscrew both bolts, tap the gearbox housing with a wooden block, and the anchor will detach from it. In this case, the bearing will remain on the shaft. Remove all bearings from the shaft with a puller.

Video: how to remove and what can be the difficulties

Put the new bearing in the gear case from the side of the rotor. Screw the plate, because of which the impeller was broken. Insert the gear inside the casing and bait the nut so that it fits into the grooves of the gear. Put the impeller on the new anchor, insert the anchor into the gear case. Tighten the nut.

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