Drill Speed ​​Control Does Not Work

Today it is impossible to find a person who would not know about the existence of an electric drill. Many had to use this tool. But far from everyone knows how this indispensable thing in the economy works.

Drill Speed ​​Control Does Not Work

Inside the body of the drill there is an electric motor, its cooling system, gearbox, drill speed regulator. The operation of the speed control of the drill is worth a little more discussion. All parts wear out during operation, the drill power button is especially susceptible to this process. And with it the speed control system is directly connected.

The purpose of the speed controller

Soft starter drill.

The speed controller of a modern electric drill is located inside the power button of the device. To achieve such small sizes allows microfilm technology, according to which it is assembled. All parts and the board itself, on which these parts are located, are small in size. The main part of the regulator is a triac. The principle of its operation is to change the moment of circuit closure and turn on the triac. It happens like this:

  1. After the button is turned on, the triac receives a sinusoidal voltage on its control electrode.
  2. The triac opens, and current begins to flow through the load.

With a larger amplitude of the control voltage, the triac turns on earlier. The amplitude is controlled by a variable resistor that is connected to the trigger of the drill. The button connection scheme in different models may be slightly different. Just do not confuse the speed control with the reverse control device. These are completely different things. Sometimes they can be placed in different buildings. The speed controller may include a capacitor and both wires from the outlet.

Using a drill as a machine

Figure 1. Typical drill revolutions controller.

Hand drill can be used non-standard. A variety of machines are made on its basis: drilling, grinding, circular and others. In such machines, the speed control function is very important. In most household drills, the revolutions are regulated by the start button of the device. The harder it is pressed, the higher the revs. But they are fixed only at maximum values. This in most cases can be a significant drawback.

Video: Drill Speed ​​Control Does Not Work


You can get out of this situation by self-manufacturing a remote version of the speed controller. As a regulator, it is quite possible to use a dimmer, which is usually used to adjust the illumination. The controller circuit is quite simple and is shown in Fig. 1. To make it, you need to connect wires of different lengths to the outlet. A long wire at the other end joins the plug. The rest is going according to the scheme. It is recommended to use an additional circuit breaker, which will turn off the device in the event of an accident.

Homemade speed controller is ready. You can perform a test run. If it works normally, you can put it in a box of a suitable size and fix it on the bed of the future machine in a convenient place.

Repair buttons with speed control

Figure 2. Scheme of the speed controller for microdrills.

Button repair is a rather complicated process that requires certain skills. When opening the case, some parts may simply fall out and be lost. Therefore, caution is needed in the work. In the event of a malfunction, the triac usually fails. This item is very cheap. Dismantling and repair occur in the following order:

  1. Disassemble the button housing.
  2. Rinse and clean the inside.
  3. Remove the circuit board with the circuit on it.
  4. Solder the burnt part.
  5. Solder a new part.

Disassembling the case is very simple. It is necessary to bend the sides and remove the cover from the latches. Everything needs to be done carefully and carefully so as not to lose 2 springs that can pop out. Cleaning and wiping the inside is recommended with alcohol. Clips-contacts in the form of copper squares slide out of the grooves, the board is easily removable. A burnt triac is usually clearly visible. It remains to solder it and solder a new part in its place. The controller is assembled in the reverse order.

Microdrill RPM

The scheme of the hammer drill.

Many have to drill printed circuit boards. Usually, a micro drill made of various parts with one’s own hands is used for such work. For such tools, you can also make a speed controller. There are many schemes for manufacturing. A similar circuit of the speed controller is shown in Fig. 2. All items are pretty affordable. The LM317 chip is mounted on a radiator to protect it from overheating. Conventional capacitors, electrolytic, 16 V.

Diodes of the brand 1N4007 can be changed to any others that can withstand a current of 1 A. The AL307 LED can be replaced by any other. The whole circuit is assembled on a fiberglass board. Resistor R5 can be wire or other power, 2 watts.

The power supply voltage is 12 V. With a higher voltage, you will have to change the capacitors in the circuit. The finished product usually begins to work immediately. The engine speed is regulated by a resistor P1. Sensitivity to the load is set by the resistor P2.

The rotational speed control of the drill is a necessary device, especially when the drill is used as the basis for the manufacture of a home-made machine.

In modern devices, this device is located in the start button. Homemade device can be placed in any suitable housing. There are a lot of manufacturing schemes.

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