In detail: do-it-yourself grinder repair Bearing replacement from a real master for the site my.housecope.com.
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A detailed photo report on replacing the bearings of an angle grinder armature (grinders) 1400 W 220V.
The angle grinder got its nickname “Bulgarian”Back in the days of the Soviet Union. Because, at that time, this instrument was manufactured and supplied from Bulgaria. Bulgarian in the arsenal of home tools, the most versatile and multifunctional assistant. Bulgarian in operation, it is exposed to strong and uneven loads and long periods of operation, therefore, malfunctions occur more often than with other power tools.
In my Bulgarian when turned on, an extraneous sound and increased vibration appeared. It is more expensive to operate a tool with such characteristics further.
Grinder repair start by unscrewing the four screws on the gearbox cover.
Prying off with a screwdriver, remove the gearbox cover assembly with a secondary shaft and gear. The bearing of the output shaft turned out to be working, without backlash and jamming.
But the front armature bearing - completely crumbled. The bearing balls were in the gear grease and the small gear retaining ring was worn on one side. To replace the front bearing, you must first unscrew the armature contact brush caps and remove the brushes.
Then we unscrew the four screws securing the grinder gearbox to the stator and remove the armature together with the gearbox housing.
To remove and install the armature gear retaining ring, you need to make a simple tool. For this I used old scissors. The ends of the scissors on emery were ground off, as in the photo.
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Video (click to play). |
This is the view I got from my retaining ring. For the convenience of mounting the retaining ring when assembling the reducer, the ends of the scissors were heated red-hot with a gas burner and bent at right angles to the plane of the scissors. Then they were again heated and cooled in engine oil.
After dismantling the armature gear, I removed the armature from the gearbox housing. This is the view of the front armature bearing.
We buy new bearings and a retaining ring in the store, continue grinder repair.
The outer cage of the armature bearing is removed from the gearbox housing by lightly tapping on a metal screwdriver inserted into the groove of the cage from the inside of the gearbox housing. It is important not to skew the cage when pressing out.
But the inner bearing race was tightly seated on the armature shaft.
To dismantle it, I used a standard tapping tool holder.
Studs were unscrewed from it for rotation when threading. And the rod holder itself is installed on the bearing race, so that the screws for fixing the rod fit into the groove of the bearing race. Then tighten the screws evenly on each side and thus securely attach the holder to the holder. Now we grab the puller with the paws of the tool holder and remove the holder from the shaft.
This is the view of the front bearing of my armature grinders.
New bearings must be filled with grease. To do this, you need a sharp awl, Litol 24 grease and a mandrel for mounting bearing caps. To lubricate a closed bearing, you need to remove the cover by prying it with an awl, as in the photo.
Now we fill the bearing with grease and put the cover in place.
To put the cover in the bearing without damage, you need to select a mandrel in diameter slightly larger than the outer diameter of the bearing cover. I used a socket wrench head.
The bearings are lubricated.Press the front bearing into the gearbox housing using the outer race of the old bearing and fix it with a flange.
At the anchor, the anchor collector is cleaned with P1000 sandpaper. With a stationery knife, carefully, without much pressure, we clean the paths between the collector lamellas. And after these operations, we carefully wipe the collector with a cotton napkin moistened with white spirit or other solvent.
Next, you need to press the armature shaft into the inner race of the front bearing. To do this, place the gearbox housing on a wooden surface with the bearing facing up. We insert the armature shaft into the bearing cage from above and lightly tap it through the mandrel, along the rear armature bearing we put the armature in place.
We put a small gear on the armature shaft. If, after installing the gear, the groove for the circlip extends beyond the end of the gear, then the installation is correct. We put the retaining ring in place.
If the groove does not come out due to the end of the gear or is halfway out, the shaft must still be seated in the housing.
After these operations, remove the old rear bearing from the armature shaft and install a new one. We place the armature with the gearbox in the stator and tighten the four screws securing the gearbox. We check the shaft for rotation. The shaft should rotate easily without jamming in the bearings. We put in place the contact brushes and screw their covers. Now we put a special lubricant for angle grinders in the gearbox grinders and put in place the cover of the gearbox with the secondary shaft.
Tighten the four fastening screws and check grinderby plugging into the network.
Bulgarian should quickly gain momentum and work without extraneous overtones. On this grinder repair can be considered complete. Good luck with your work!
Angle grinders during the Soviet era were made in Bulgaria. Therefore, the angle grinder began to be called a grinder. Currently, there are many companies for the production of angle grinders of various models. But the basic elements are the same. Having familiarized yourself with the device, probable breakdowns and diagnostics of the tool, you can repair the grinder of any modification with your own hands.
The grinder is designed for grinding and cutting various materials.
The main elements of the grinder
The grinder consists of the following elements:
- The flat aluminum alloy gear housing provides better heat dissipation.
- Carbon brushes.
- Fastening the handle.
- Electronic soft start system. Prevents start-up jerk and reduces starting loads on the engine.
- Quick-detachable protective cover.
- Ball bearings.
- Electric motor.
- Grinder switch.
A large selection of bearing products is offered by the Termopolis company -
Main breakdowns and reasons:
For troubleshooting, the grinder must be disassembled.
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Remove the nut that holds the scraper disc.
Unscrew the bolts securing the protective cover.
Unscrew the bolts of the grinder body and those with which the body is attached to the gearbox.
Remove the upper part of the back case. Unscrew the bolts securing the cord. Remove the wires and the button from their grooves. In some models, for example, in DWT, the rear case is not disassembled into parts, but removed entirely.
Unscrew the gearbox bolts located around the casing mount.
To disconnect the armature from the aluminum housing, unscrew the nut located in the gearbox housing.
Assemble the tool in reverse order.
During operation, the disc can be tightened so tightly with the nut that it begins to crumble. It is impossible to unscrew the nut with a wrench. And you don't need to do this, since you can break the grinder. First, break the disc down to the nut. Then find a metal plate slightly thinner than the scratch disk. With its help, grind off the remnants of the disc under the nut. It can be easily unscrewed with a key or by hand. To avoid bringing the tool to this problem, place a washer under the nut.
For some grinders, for example, Bosh, the casing is not bolted, but snapped into place. To remove it, you need to turn the cutout of the casing perpendicular to the grinder. To dress, turn until it clicks.
The stator is checked with a multimeter.
- Turn-to-turn closure. Set the resistance mode to 200 ohms. Connect the test leads of the device to the ends of one winding. One means open, and zero means short circuit between turns. If it shows a resistance of more than 1.5 ohms, then check the second winding. Both windings should have approximately the same resistance.
- Breakdown to ground or short circuit of the winding with the metal stator housing. Set the multimeter to the maximum resistance mode. Connect one probe to the end of the winding, the other probe to the metal stator housing. The unit indicates the absence of breakdown.
First, visually inspect the manifold and winding. There may be visible damage: black marks, bent windings, raised, worn or burnt collector plates. After inspection, proceed with the tester check.
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Put a resistance of 200 ohms. Connect the test leads to the two adjacent manifold plates. If the resistance is the same between all adjacent plates, then the winding is in good order. If the resistance is less than 1 ohm and very close to zero, there is a short circuit between the turns. If the resistance is two or more times higher than average, then there is a break in the winding turns.
The determination of the breakdown to ground is done in the absence of a winding break. Set the maximum resistance on the scale of the device. 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 move the other along the plates.
Put the tester in the dialing mode.
Insert one probe into the outlet of the button and the other into the opposite inlet.
Click the button. A sound signal indicates the health of this part of the button.
Do the same with the other input and output buttons.
If you actively use a grinder, then you are a good craftsman. It will not be difficult for you to understand the structure of the tool and fix it with your own hands. First, find the problem and determine which parts to check. Repair the grinder carefully, without haste, so that a minor breakdown does not turn into a major one.
