Bosch Hammer Drill Does Not Hold Drill
A puncher, like any electric tool, requires a careful attitude, proper operation and timely preventive maintenance. If these standards are neglected, then the device may fail without having developed its resource. Repair of the punch in case of some malfunctions can be done by yourself, and to eliminate breakdowns associated with the electrical part of the engine, specialist assistance is required.
The main malfunctions of the punch and their external signs
All malfunctions of the unit can be divided into 2 groups: mechanical and electrical.
If any mechanical malfunction appears in the punch, then its presence can be identify by ear (noise increases, a rattle appears).
You may also experience increased vibration or an unpleasant odor emanating from the unit body.
So, the following can be attributed to mechanical breakdowns:
- breakdown of the device operation mode switch;
- worn rubber striker and striker;
- failure of the shock mechanism;
- failure of the unit barrel due to wear and tear;
- gear teeth breakage;
- breakage of the chuck, as a result of which the drill flies.
Faults associated with the electrical part of the punch, can also be accompanied by an unpleasant odor from the apparatus, sparking. You may also notice that the engine heats up quickly and buzzes, without spinning, or smoke appears from it.
Electrical breakdowns of the apparatus include such as:
- the device does not turn on;
- breakdown of the start button;
- brush wear;
- clogged collector;
- violation of electrical contacts;
- burnout of the stator winding or rotor of an electric motor.
Punch Disassembly Algorithm
To eliminate mechanical and electrical problems (with the exception of a broken electric plug), disassembly of the unit casing cannot be dispensed with. The most popular among masters, both home and professional, are the brands of Bosch, Makita, Interskol, Energomash punchers. The design of units of different manufacturers is approximately the same, therefore, the methods of disassembling the devices will be similar. But you should not disassemble the device completely, since it will be difficult to assemble it back. The photo below shows how a fully disassembled punch looks like.
The disassembly of the unit for troubleshooting should be carried out carefully, with an inspection of each removed part. So that the assembly does not cause difficulties, it is better to photograph the disassembly process. If you did not find any external defects on the device, then it is recommended to start disassembling it with a cartridge.
- First remove the boot (1) made of rubber.
- Carefully, so as not to lose, use a screwdriver to remove the snap ring (2) and then a plastic boot (3).
- The next step is not to lose small ball, which is under the washer (4). Remove the washer (4), plate (5) and spring (6), as well as ball (7). It is with the wear of these parts that the drill falls out of the cartridge. Some cartridge models may have extra balls and washers.
Disassemble the case
If disassembly of the unit body is required, then first you need to remove the mode switch.
- Put the switch to the position of “Blow”. Usually a hammer is drawn on this case on this case. If this mode is not available, put the switch in the position “Impact drilling”.
- Next, you should click on the button located on the handle of the switch, and turn it slightly below the icon with the image of a hammer until a distinctive click is heard.
- After that, it is necessary to pry the switch with a screwdriver and pull it towards you, remove it. In some models of units, this switch can be screwed to the housing.
Dismantling the electric part of the punch
To get to the electrical part of the device, if there are suspicions that it may be a malfunction, you must perform the following steps.
- Loosen the screws holding the back cover and remove it.
- Unscrew the fasteners holding the network cable.
- Next, pull out the wires from the mounts and remove the start button.
- Remove all wires attached to the stator.
- Remove the brushes by unscrewing the fixing bolts.
- Separate the enclosures of the electrical and mechanical parts of the apparatus by unscrewing the corresponding bolts. For separation, use “flat ”screwdriver.
- Remove the rotor from the gearbox. If you need to replace the bearings, use a special puller.
- Remove the air intake located in the body of the electric part of the punch.
- Disconnect the stator from the housing. To make it easier to get out of the casing, it is recommended to pull the stator with a light tapping on the body with a wooden object.
If you want to disassemble a barrel perforator, with a vertical arrangement of the electric drive, then the handle is first removed, and then the bolts holding the engine are unscrewed.
Replacing motor brushes
The main sign that it is time to change the brushes is the formation of increased sparking in the area of the electric motor collector, the rapid heating of the brush holders, and the smell of burning. When the brushes are not worn out, the spark can be seen only under them. Otherwise, a spark is visible throughout the collector circle.
The presence of sparks around the collector with worn brushes is a sign of bearing wear, insulation failure of the rotor or stator, burnout of the collector plates, burnout of the stator or rotor.
Another sign that the stator burned out is the presence of sparks under only one electrode. If you have a tester, then they can check stator and rotor: Measure alternately the resistance on the rotor and stator. If it is the same on both windings, then everything is in order with the stator. If you notice that your rotary hammer has obvious signs of problems with the rotor or stator, you will have to carry the device to a service center for repair. As for the brushes, they can be changed independently.
To get to the place where the brushes are installed, you will need to disassemble the case in which the engine is installed, or simply remove the back cover. Opening the cover, you will see the brushes fixed in special holders. The photo below shows how these details look.
Video: Bosch Hammer Drill Does Not Hold Drill
The brushes that are installed on the motors of punchers are of 3 types.
- Graphite. differ in durability, but since they are very hard, rubbing them to the collector is not ideal, which negatively affects the latter.
- Coal. they are easy to grind to the collector, providing good contact, but wear out quickly.
- Carbon Graphite –– an ideal option, as they are a mixture of 2 components that complement each other.
It is very important not to wait until the engine sparkles, and after that change the brushes. Replacement is needed after they wear out 1/3 of the nominal value (8 mm). Even if one brush is worn less than the other, you still need to change both.
Pay attention to the condition of the spring in the new brushes and the fastening of the contact. If the spring flies during engine operation, it will receive significant damage. Also, if the spring is weak, then it cannot provide good contact.
Be sure to change the brushes well before clean rotor and stator from residues of graphite or coal dust. These parts can be cleaned with technical or medical alcohol.
Next, you should fix the electrodes in the holders and grind them to the collector. To do this, put a piece of fine sandpaper on the collector and rotate in different directions to produce lapping electrode. Lapping continues until the contact area of the electrode electrode is rounded. This will ensure its best fit to the collector plates and, consequently, better contact.
The scheme of the device of the percussion mechanism, its malfunction and repair
Impact mechanisms of perforators differ in their design, depending on which family the devices belong to. Therefore, the repair of these mechanisms will occur according to different principles.
Rotary hammers with a vertical arrangement of the engine usually have a shock block based on a crank mechanism (KShM). The following is a diagram of this type of impact mechanism.
The following photo shows the apparatus in a section where you can see the location of the cshm.
The shock mechanism of a unit with a vertical engine may have the following malfunctions. The connecting rod mechanism has a separate bearing that is mounted on the cam of the wheel with an eccentric, but sometimes it can be located at the base of the connecting rod. In some models of rotary hammers, a plain bearing may be installed in this place (instead of a rolling bearing), requiring constant lubrication. If she is not there, or she is already old, then this knot wears out. During the repair, the connecting rod and eccentric barrel will have to be completely replaced.
Another common problem is the striker broke. This malfunction can be calculated if you notice that your hammer is no longer hit. To get to the striker, you will need to completely disassemble the barrel of the device. It is done as follows.
- Disconnect the barrel from the punch body, remove the cartridge (see description above). Tap the barrel on the table so that the piston falls out of it. Take a rubber mallet and knock the barrel out of the body.
- Remove the snap ring holding the bearing.
- Remove the bearing itself and gently tap the table to remove the balls.
- After removing 3 balls, you can pull out the raster sleeve.
- Also, as in the previous case, remove the balls located on the sleeve, but do not confuse them with those that were removed earlier (these balls are smaller in diameter). After removing the balls, you need to insert a screwdriver into the sleeve and push out the striker.
In this case, the whole striker. But if it is broken, then replace it with a new one. You should also pay attention to the sealing gum and the seals in the barrel. If they are worn, they must be replaced.
Pistol Type Hammers
The device of the percussion mechanism of the pistol-type unit is slightly different from the same mechanism intended for use in the barrel-type apparatus.
Its main difference is that the piston does not move with the help of a connecting rod, but from a swinging (“drunk”) bearing. Therefore, the most common failure of this unit is the wear of a “drunk” bearing, which must be replaced.
The following photo shows a destroyed “drunk” bearing, which is the reason that the hammer stopped hammering.
The swinging bearing is removed using a flat screwdriver, which you need to pick up the bracket, and remove it. After that, the bearing is easily separated from the gear housing.
When replacing a collapsed bearing should be good flush gear, since it is in his case that fragments of a broken part can remain.
After cleaning and installing a new bearing, apply a greasy layer of grease to this unit.
Also, the reason that the device does not hit can be a broken firing pin. To get it, you need to remove the snap ring, which is visible in the hole.
Take a small screwdriver, pick up the ring with it, and slide it to the right (towards the gear).
Do the same on the other side of the part. Next, insert a screwdriver into the hole of the part and push the removed internal parts of the mechanism.
After this action, the retaining ring and the housing in which the broken impact striker is located will be easily accessible.
If you disassemble this case, you will see the “culprit” of the malfunction, due to which the hammer does not hammer.
When assembling the impact mechanism, do not forget to generously apply grease to all its parts.
Other mechanical breakdowns and their elimination
In addition to breakdowns associated with the percussion mechanism, other mechanical breakdowns can occur in the hammer drill.
There are times when the unit mode switch fails. This is mainly due to dust clogging this node. To repair the switch, you will need to disconnect it from the housing (see above for how to do this) and clean it from dirt. If you find any damage to the plastic parts of the switch, you will have to replace it.
The reason that the device stopped working normally, namely, stopped drilling and hammering, may lie in worn teeth on the rotor shaft.
If this happens, then the teeth will be worn out and on the intermediate helical gear.
This problem occurs when the tool is jammed or the clutch is malfunctioning. Failure is eliminated by replacing the intermediate gear and motor rotor.
The drill does not hold in the cartridge
The reason that the punch does not hold the drill lies in the breakdown of the cartridge and the wear of the parts included in its composition:
- ball deformation occurred;
- restrictive ring worn;
- fixing spring sagged.
You will need to disassemble the cartridge and replace the problematic parts.
Drill stuck in a punch
The reasons that the drill is stuck in the cartridge of the apparatus may be as follows.
- Before installing the tool, you did not apply grease to its shank. It will be necessary to move the sealing gum of the chuck and inject it into the place of the tool WD-40.
- Dust fell under the balls. Perform the same operation as above.
- If you used a conventional drill inserted into the adapter in a puncher, also process it fluidWd-40, wait a couple of minutes, and, gently tapping the surface of the clamp with a hammer, loosen the equipment in different directions. Typically, after these steps, the clamping jaws open and allow the drill to be removed.
- The tool shank riveted. You will need to first fill in the WD-40 fluid and try to pull out the drill. If all else fails, then you need to disassemble the cartridge and knock out the snap. You can also use the tips on how to get a tool stuck in the device from this video.