Replacing the screwdriver chuck: how to unscrew the threaded and remove the tapered

The screwdriver is an effective tool that allows you to speed up many construction, locksmith and assembly work. It successfully replaces not only a large assortment of screwdrivers and wrenches, but can also act as a drill. However, any technique is subject to wear and tear. Breakdown of various components may occur. Often there is a need to replace the chuck on the screwdriver. To successfully carry out repairs, it is worthwhile to study in more detail the device of the instrument.

Device and malfunctions

All screwdrivers have approximately the same device. Certain varieties may include a number of additional nodes. But any model is equipped with the following mandatory elements:

• DC motor;
• planetary reductor;
• load limiter;
• battery.

The most common malfunction is a broken battery. The easiest way is to replace a non-working battery with a new one. If the model is old and the required batteries are not on sale, you can try to adapt the filling from another by placing it in the case from the old one. Care should be taken to ensure that the electrical characteristics of the batteries used for replacement are correct.

Nickel-cadmium batteries have a memory effect. Sometimes, to restore their normal operation, it is enough to carry out several full discharge and charge cycles. This will restore the battery to its original capacity.

Repair of most of the internal components of the tool requires high qualifications and significant labor costs. An external unit, which is relatively easy to replace yourself in the event of a malfunction, is the cartridge.

Three-jaw chuck

Most screwdriver models use three-jaw chucks. The chuck carries the bulk of the load during tool operation. This can lead to frequent malfunctions. The most common problems are:

• cam play;
• misalignment of the cam and the clamping element relative to the axis of rotation;
• uneven tightening torque;
• jamming.

To carry out repairs, it is necessary to find out the cause of the breakdown. To do this, you must first remove the cartridge. Before doing this, you should find out the method of fastening. There are two options:

1. The tool cone is the simplest and most reliable method of fastening. This type of connection allows a high torque to be transmitted without the risk of damaging the shaft or chuck bore.
2. Thread - easier to manufacture, but less reliable when constantly working with heavy loads. If the torque is exceeded or the tool is jammed in the drilling mode, the thread can be cut.

As an additional fixing fastener that protects against accidental detachment of the chuck during operation, a screw is often used, which is screwed into the shaft from the chuck side.

To determine the type of fastening, you should carefully study the marking. Typically, the fixing method is indicated directly behind the shank diameters range:

• In household power tools, for compactness, shortened versions of the tool cones are used, marked with the letter B and a number showing the diameter of the thickest part of the cone in millimeters. Detailed information about the designation is contained in GOST 9953–82. This designation will be required when purchasing a new cartridge.
• In the case of using a threaded fastener, there will be a metric or inch thread designation.

Dismantling methods

After determining the type of fastening, you can start removing the cartridge. The fixing method determines the dismantling method. It is helpful to consider both options.

Threaded fastening

It is easy to remove the chuck from Bosch, Hitachi, Metabo, Makita and other popular brands of screwdrivers, because in most cases they are threaded. For this it is recommended to use the following algorithm:

• Rotate the cage to fully open the cams to the sides to gain access to the fixing screw.
• Unscrew the fixing screw with a screwdriver. Depending on the model, the head can have a Phillips or Hex socket. It should be noted that the screw has a left-hand thread, which reduces the likelihood of spontaneous loosening, therefore, it must be rotated clockwise.
• Clamp the short side of the L-shaped hex key in the jaws.
• Set the screwdriver adjuster to the drilling mode to exclude the operation of the torque limiting ratchet.
• Switch the direction of rotation to reverse. The screwdriver shaft has a normal right-hand thread, so the chuck must be turned counterclockwise.
• Prepare a solid object. You can use the edge of a metal workbench, a brick, a piece of a metal profile.
• Operate the screwdriver and bring it to a solid object with a rotating wrench. The chuck should turn when the clamped hex wrench hits a solid object. If this does not happen, it is worth repeating the procedure several times. If the thread is strongly stuck, it may be necessary to additionally act on the wrench with hammer blows.
• The spun chuck can be easily unscrewed by hand by rotating it counterclockwise.

It is recommended to carry out these operations with a fully charged battery. This will provide sufficient torque and impact momentum.

In advanced cases, when such manipulations do not lead to success, you will have to disassemble the body and remove the shaft along with the chuck. For dismantling, the shaft is strongly clamped in a vice, and the chuck is unscrewed using a key and a lever, which can be used as a piece of pipe.

More expensive products may have special grooves on the shaft, allowing instead of a vice to fix the shaft with a wrench. Unfortunately, in modern models this is less and less common, since manufacturers pay less attention to the possibility of repair and advise in case of breakdowns to purchase a new tool.

It is highly recommended to pre-treat the threads with an anti-corrosive agent type WD-40, instead of which you can use white spirit thinner, gasoline or kerosene. This will make it easier to loosen.

The cartridge can only be removed from a cooled tool. If the device becomes hot during operation, there is a possibility of expansion of the threads. This will make unscrewing difficult or impossible.

Tool taper

The question of how to unscrew the chuck on a screwdriver is relevant only for threaded fasteners. The removal method in the case of tapered fixation is fundamentally different. It will be necessary to apply shock loads to the cartridge itself, but the plastic case cannot withstand this, therefore, the cone mount in screwdrivers is extremely rare.

If you had to deal with a tapered fixation, you can use the following techniques:

• If there is a gap between the tool body and the chuck, insert a suitable wrench. The key arms rest against the base of the cartridge and strike the handle. The tool body can be gently clamped in a vice through a soft gasket.
• If the gap is absent or minimal, you need to find a metal wedge and carefully hammer it between the chuck and the body. Sometimes a special wedge is supplied with the device for this purpose.

If the chuck attached to the cone has a retaining screw screwed in from the jaw side, this can aid in disassembly. Do not remove the screw completely. After unscrewing it a few turns, you can try to knock on the head. This will require a piece of metal bar and a hammer. With an impact screwdriver, the task becomes even easier, since the blows can be applied directly to the handle.

Disassembly options

Before deciding to buy a new unit to replace a broken one, it may be necessary to check the possibility of repair. To do this, you will have to disassemble the screwdriver chuck. The design is based on an internal tapered shaft. It houses the cam guides. The outer surface of the cams is threaded to match the inner thread of the cylindrical cage. When the cage rotates, the cams move along the guides, and their clamping part converges or diverges to the sides, depending on the direction of rotation.

The cage is protected from axial movement by a locking screw or a special nut. To disassemble the cartridge, unscrew the screw or top nut. The specified nut is most easily unscrewed with a gas wrench when the body is clamped in a vice.

The situation is complicated when the clip is jammed. In this case, it cannot be removed even after removing the locking element. To eliminate the problem, it is advisable to keep the cartridge in a solvent for some time, then clamp it in a vice and try to remove it with considerable effort. If such manipulations do not lead to success, it is better to replace the cartridge with a new one.

In some cases, disassembly is not possible. This is often done in order to force the owner to purchase a new cartridge. In an extreme situation, this problem can sometimes be solved. For disassembly, you will need to cut the clip.

If everything is done carefully, after repair or cleaning, you can try to connect the cage elements with a clamp or other homemade fixing device. but important to rememberthat this method is only suitable for temporary repairs. In order to ensure the safe operation of the tool, it is necessary to replace the cartridge restored in this way with a new one as soon as possible.

Types of breakdowns

Most often, chuck malfunctions occur as a result of damage to the most vulnerable elements: threads on the cage and counter threading on the cams. If the damaged areas are small, the defects can be removed with a file. After work, the surfaces must be cleaned with a fine sandpaper.

In the overwhelming majority of cases, the threaded elements inside the chuck are made with large geometric tolerances, therefore grinding off individual threads of the thread and even completely removing some of its sections often does not affect the functioning of the clamping mechanism. The centering accuracy of the tool to be clamped may sometimes be slightly affected by backlash when moving or skewing the cam. This can adversely affect the use of a screwdriver as a drill, but it usually does not interfere with tightening screws and self-tapping screws.

If the malfunction is caused by excessive play or cam skew, it cannot be repaired. In this case, only replacing the damaged element with a new one can help. Sometimes a malfunction can be caused by the simple ingress of chips into the housing. In this case, it is enough to remove metal particles and metal dust, and then rinse all parts in any solvent or kerosene. The assembly is carried out in reverse order without significant effort.

If the damage is significant and cannot be repaired, you will have to buy a new cartridge. It is recommended not to throw away the damaged unit, as its component parts may be required as spare parts in the future. Sometimes a broken cam can be replaced with a similar one, and even removed from a chuck from another manufacturer.

It is difficult to overestimate the benefits of having a screwdriver in any household. It greatly facilitates many repairs. Some malfunctions of the device may require the intervention of a qualified technician to carry out repairs. However, you can change the battery or cartridge yourself. In most cases, it will not be difficult to replace a broken cartridge with a new one. When working, you should strictly adhere to the instructions corresponding to the method of fastening the assembly.