How to Change Brushes on a Hammer

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Rotary hammer

As you know, the main source in the punch are brushes. It is important to monitor their condition and the cleanliness of the collector. In Makita 2450 and 2470 rotary hammers, carbon brushes CB-419 art.191962-4 are used. Factory carbon brushes are recommended to be replaced after 80 hours of operation. Both brushes are subject to replacement, regardless of the degree of wear.

Signs of brush wear

Do not confuse the usual small sparking that is present when working with partial gliding of sparks in a circle, this is permissible under loads and with a new tool until the brushes are ground.

The first manifestations of brush wear are strong sparking and extraneous sound. Stop work immediately!

Timely replacement of carbon brushes prevents the failure of more expensive parts of the punch. The cost of a set of carbon brushes is not comparable with the cost of the rotor or stator of any power tool. Do not save on small, so as not to lose more. The conclusion is simple: often change carbon electrobrushes. Do not forget, if one brush fails, the other should change automatically.

The critical length of the carbon brushes of a Makita rotary hammer cannot be less than 8 mm

When replacing, it is worth taking a closer look at the anchor, which is the development of the collector.

With a noticeable deepening, the collector should be sanded to a level state, if this is not done, even the original new brushes will spark, which will lead to even more burnout of the collector.

After installing new brushes, be sure to let idle for at least 10 minutes without load.

How to Change Brushes on a Hammer

The procedure for the production of coal from other brushes

The process of manufacturing carbon brushes for a Makita rotary hammer

Work begins with the preparatory phase. It is necessary to choose the right cross section of the workpiece of the coal rod. Here are the dimensions of the factory carbon brushes CB-419A in mm (6x9x12). Selected carbon rods must be larger or the same size as used in Makita rotary hammers.

If you picked up blanks of a larger cross section, they are filed with files or with sandpaper. But you can use a fairly simple device. A special device called a “fungus” is clamped into the electric drill. Almost any master has this device. It is used in the process of grinding surfaces. The device is a circle with Velcro, on which the grinding disk of the desired diameter is attached.

Try to securely fasten the power drill to the bench or table. The drill can be fixed with clamps, clamps, or a temporary fixture. Insert the fungus into the drill chuck, fix a circle of sandpaper No. 100 on it.

After turning on the drill, adjust the frequency of rotation of the chuck. It is preferable to start grinding at low speeds. This will allow you to properly control the grinding process.

Constantly monitor the dimensions of the carbon brushes.

Replacing the brushes on a Makita rotary hammer

Especially important are the cross-sectional dimensions of the electric brushes. Brushes should fit into the brush holder tightly, but move freely.

Homemade electric brushes

We find a suitable material, cut it to size with a margin of 2 mm. Next, bring to emery to the desired size. As the top contact on the wire, it is recommended to use the contacts of the old brushes, soldering them to the contact wire, if any.

If there is no contact group, to fix the wire, a hole of a smaller diameter is drilled in the electric brush than the diameter of the copper braid. The braid is twisted, inserted into the drilled hole and wedged on the opposite side by copper wire. Everything is ready, install and check for sparking.

Replacing the punching brushes: DIY repair rules

Power Tool Repair Price List


We ask you to prepare in advance all the information necessary for the master, namely:

  1. Equipment manufacturer
  2. Model of technology
  3. Serial number