The simplest scheme
The soft starter with speed control on the KU 202 thyristor has been widely used due to its very simple design (diagram 1). Its connection does not require special skills. It is very easy to get radio elements for him. This model of the regulator consists of a diode bridge, a variable resistor (plays the role of a U regulator) and a thyristor tuning circuit (supplying U to a control output with a nominal value of 6.3 volts) of a domestic manufacturer.
Due to the size and number of parts, this type of regulator can be integrated into the body of a power tool. In addition, you should remove the handle of the variable resistor and the speed controller itself can be modified by building in a button in front of the diode bridge.
The basic principle of operation is to adjust the speed of the electric motor of the tool by limiting the power in manual mode. This circuit allows the use of power tools up to 1.5 kW. To increase this indicator, it is necessary to replace the thyristor with a more powerful one (information about this can be found on the Internet or in the reference book). In addition, it is necessary to take into account the fact that the thyristor control circuit will differ from the original one. KU 202 is an excellent thyristor, but its significant drawback is its adjustment (a selection of parts for the control circuit). To implement a soft start in automatic mode, circuit 2 is used (soft starter on a microcircuit).
Smooth start on a microcircuit
The best option for manufacturing a soft starter is a soft starter circuit based on one triac and a microcircuit, which controls the smooth opening of the p-n type junction. The device is powered by a 220 V network and it is easy to assemble it yourself. A very simple and universal scheme for the soft start of the electric motor also allows you to adjust the speed (diagram 2). The triac can be replaced with a similar one or with characteristics exceeding the original, according to the manual of radioelements of the semiconductor type.
Scheme 2. Scheme of soft start of the power tool
The device is implemented on the basis of the KR118PM1 microcircuit and a triac. Due to the versatility of the device, it can be used for any tool. It does not require configuration and is installed in the break of the power cable.
When the electric motor is started, U is supplied to KR118PM1 and the charge of the capacitor C2 smoothly increases. The thyristor opens gradually with a delay depending on the capacity of the control capacitor C2. With a capacitance C2 = 47 μF, there is a start-up delay of about 2 seconds. It depends in direct proportion to the capacitance of the capacitor (with a larger capacity, the start-up time increases) When the angle grinder is turned off, the capacitor C2 is discharged using the resistor R2, the resistance of which is 68 k, and the discharge time is about 4 seconds.
To control the speed, replace R1 with a variable resistor. When the parameter of the variable resistor changes, the power of the electric motor changes. R2 changes the amount of current flowing through the input of the triac. The triac needs cooling and, therefore, a fan can be built into the module case.
Thus, to start the electric motors of various tools, it is necessary to use a factory-made or home-made soft starter. Soft starters are used to increase the service life of the tool. When the engine starts, there is a sharp increase in the current consumption by 7 times. Because of this, burning of the stator windings and wear of the mechanical part are possible. Soft starters can significantly reduce the starting current. When making a soft starter, you yourself need to follow safety rules when working with electricity.
Originally posted 2018-07-04 07:37:29.
Soft starters with three wires
By the way, be careful, there are similar devices, but with three wires. For example XS-12 / D3.
Or other models similar in appearance to KRRQD.
But they are assembled on a slightly different principle and they need to be installed after the START button, in the tool itself. The voltage should be applied to them only at the moment of closing the start button of the angle grinder and immediately disappear after releasing it..
The connection diagram for them is as follows:
The phase is fed to contact “A”, zero to “C”. Next, the phase with the output control wire goes to the engine (this is just the third wire).
Without a button, such a device will be constantly under voltage of 220V, which is not permissible.
There is no such thing in a two-wire block, since it is connected to an open circuit, and a voltage (potential difference) is applied to it only at the moment of starting and operating the tool.
Another point is the so-called electric brake or brake winding on the end faces. It may not work with a 3-wire external soft starter, but with a 2-wire model it will.
Features of installation of the finished block
When buying and installing a factory regulator inside an angle grinder, most often you have to modify the case – cut a hole in it to output the adjusting wheel. However, this can adversely affect the rigidity of the casing. Therefore, it is preferable to install the device outside..
The adjusting wheel changes the speed
The numbers on the adjusting wheel indicate the number of spindle revolutions.
The meaning is not absolute, but conditional. “1” – minimum speed, “9” – maximum. The rest of the numbers are for guidance when regulating. The location of the wheel on the body is different. For example, on a Bosch PWS 1300–125 CE, Wortex AG 1213–1 E or Watt WWS-900 angle grinder, it is located at the base of the handle. In other models, such as the Makita 9565 CVL, the adjusting wheel is located at the end of the casing..
DIY Grinder Vacuum Attachment for Concrete Grinding
The connection diagram of the regulator to the angle grinder is not complicated, but sometimes it is not so easy to pull the cables to the button, which is located on the other end of the device body. The task can be solved by selecting the optimal wire cross-section or by bringing it to the surface of the casing.
The regulator is connected according to the diagram
A good option is to install the regulator on the surface of the device or fasten it to a power cable. Not always everything works out on the first try, sometimes the device has to be tested, and then some adjustments are made. And this is easier to do when access to its elements is open..
Attachment to the power cord
3 ways: how to make a smooth start for a power tool with your own hands
How to smoothly start the engine?
There are five main methods of soft start.
High torque can be created by adding external resistance to the rotor circuit as shown in the figure..
By including an automatic transformer in the circuit, the starting current and torque can be maintained by reducing the initial voltage. See the picture below.
- Direct start is the easiest and cheapest way because the induction motor is connected directly to the power source..
- Connections according to a special configuration of windings – the method is applicable for motors intended for operation under normal conditions.
The use of SCP is the most advanced of all the methods listed. Here, semiconductor devices such as thyristors or SCRs that regulate the speed of an induction motor successfully replace mechanical components..
Starters for angle grinder with 20 amp triac
Devices with 20 A triacs are suitable for the professional angle grinder. Many types use special resistors. First of all, they can operate at a high frequency. The maximum temperature of the starters is fifty-five degrees. Most devices have excellent body protection. The classic scheme involves the use of 3 contactors with a capacity of thirty pF. Craftsmen believe that devices stand out for their conductivity..
- The lowest frequency for starters is about thirty-five Hz. They can function in a DC network. The model is connected through adapters. For motors with two hundred watts, such devices are perfect. Filters are often fitted with triodes. Their sensitivity index is 300 mV and no more.
- Quite often you can meet special comparators with a protection system. If we disassemble foreign models, then they have an integral converter, which is installed with insulators. The current conductance is made at around five microns. With a resistance of forty ohms, the model can hold high revs for a long time.
How to connect an angle grinder to a vacuum cleaner
Dust not only pollutes the room or work area, but also has a detrimental effect on human health..
In addition, it is much more difficult and inconvenient to work in dust. it’s hard to breathe and you can’t see anything.
There are two ways to do dust-free work..
How to choose?
Protective attachments play a huge role when working with an angle grinder, and special attention should be paid to the choice of a cover for a vacuum cleaner. Since not every fixture can fit an angle grinder and protect the room from dust well, it is important to consider some basic points before purchasing..
It is best to give preference to well-known brands that have proven themselves well among users. In addition, the nozzle should have an instruction manual and technical description that will simplify its installation and use..
To improve the efficiency of the protective cover, it must be correctly positioned and secured. The installation process is simple, even a novice wizard can handle it. Connecting the nozzle is as follows:
- first, you should close the standard casing of the angle grinder with an aerodynamic one, for this it is resting on the thrust bearing;
- then the casing is clamped onto the studs, it is fixed with screws, ensuring symmetry to the disk;
- a vacuum cleaner hose is connected to the exhaust pipe, it should freely pass into the hole in the casing;
- the installation process is completed with a control check of the fasteners, since work can only be started when the cover is securely fixed.
For how to make a dust extractor cover for an angle grinder with your own hands, see the next video.
Hi guys! I often gave something to you). But that’s how it happens with newbies. There are many topics – I want to ask a lot, share a lot. In general, the topic is this. When I was faced with grinding fiberglass, I realized that this is trash, to put it mildly. I have an orbital with a dust extractor, but no angle grinder. And since I roughly polish it at first, the picture looks like this:
Attachment on the angle grinder for connecting a vacuum cleaner How to cut concrete without dust DIY
Features of the
Most designs of the angle grinder have a dust collector. Thanks to him, dust is immediately collected from under the working surface of the device, without polluting the room. Such models are characterized by high suction power. They protect not only from dust, but also from debris. Additionally, a protective casing made of durable material is installed on the dust removal mechanism. It is able to withstand intense mechanical loads and, during surface treatment, collect various fractions, including fine dust particles, and pieces of metal or concrete.
The protective cover for the vacuum cleaner has two main functions..
- Dust proof. It prevents the spontaneous spread of debris in the work area. The dust protection element also traps small and large pieces of debris that are formed during surface treatment. In addition, this device also protects the tool itself from getting into the outer part of the body of various particles, which have a detrimental effect on the functioning of rotating parts and can subsequently disable them..
- Adjustment. The casing is not only responsible for dust removal, but also allows you to adjust the operation of the circle.
Since cleaning is carried out with a vacuum cleaner connected to the nozzle, when installing the cover, make sure that the diameter of the dust tube and the hole of the nozzle match. The nozzle in the form of a flexible hose should fit exactly into the hole and slide over the casing without any backlash.
If gaps remain between the elements, then dust can enter the room, and the performance of the vacuum cleaner will decrease..
It is recommended to use a cover for a vacuum cleaner in the following cases:
- For grinding concrete and chipping walls, floors. This type of surface treatment produces a lot of dust. In addition, most of the work is done at a height, and debris falling from above can settle throughout the room. To increase dust protection, you need to choose an aerodynamic or sanding hood that matches the heavy-duty angle grinder model and has good load bearing capacity..
- When cutting tiles. Such work is always accompanied by a large amount of dust, which not only pollutes the room, but is also harmful to human health. For this process, experts recommend choosing a cut-off or universal casing..
- For scraping wooden floors. This process is quite time consuming. It provides for the treatment of surfaces of large areas, after which a lot of debris and dust are generated. Thanks to the protective cover, scraping is quick and efficient, since the master does not need to be distracted by cleaning the working area. It is installed on an angle grinder using special fasteners..
The cover for the vacuum cleaner can be sold as a complete set with the tool, or separately. At the same time, many craftsmen make a protective device with their own hands in order to secure the working process. A homemade casing does not differ in functionality from the factory one, but it may be slightly inferior in performance. Self-made casings are able to protect the craftsman from injury, preventing particles of the processed material from flying away. But if financial capabilities allow, then it is better to purchase finished products, since they are of high quality and allow you to expand the capabilities of the device.
Depending on the type of construction work, it is necessary to purchase a special casing model. Most often, sawing and grinding covers are used for a vacuum cleaner, which are designed for an angle grinder with discs with a diameter of 125 to 230 mm.
Just five simple steps:
1) Place the angle grinder on the floor, table, etc. so that it lies with the disc upwards parallel to the plane of the base.
the angle grinder must be sufficiently stable.
2) We take a branch with pliers or some kind of clamp.
3) Turn on the angle grinder and literally saw in the branch pipe along the body, under the casing of the angle grinder, about 3 cm.
4) We take the reinforced tape, and tightly, in an interference fit, we attach the branch to the body of the angle grinder, with a slight approach (a couple of centimeters) into the saw blade.
The branch pipe must be fixed firmly so that it is kept absolutely still.
5) We take masking tape, and glue the open side of the casing with it, connecting it to the bend.
This design allows you to easily connect a construction vacuum cleaner and saw an angle grinder without dust..
For such work, you can only use a construction vacuum cleaner..
When sawing, the blade should be inserted into the material to be cut from the engine side, closer to the nozzle.
So all the dust will go through the outlet to the vacuum cleaner..
We cut objects with the engine forward.
Such a dust extraction system does not imply any major structural changes in the device angle grinder.
We just attached the pipe to the body of the instrument..
And the second part of the casing was closed with masking tape, this element can create a false impression of security.
Masking tape is only designed to protect against dust.
Therefore, it is necessary to comply with all safety measures when working with an angle grinder.
The angle grinder is considered a multifunctional tool. In addition to many advantages, it has one significant disadvantage – it generates a large amount of dust during cutting and grinding of the material. To free themselves from long-term cleaning of the room after working with an angle grinder, craftsmen use devices equipped with a vacuum cleaner. The main element of any of these devices is the protective cover. It can be easily matched to any model of angle grinder. The main thing is to be able to correctly attach the part to the exhaust system..