Electric tool brushes

Mounted Wheel Brush Mounted End Brush 9. Controlled Flare End Brush 5. Mounted Conflex Brush 4. Disc Brush 3. Bristle End Brush 2. Pencil End Brush 2. Stem-Mounted Brush 2. Crosshole Deburring Brush 1. M14 X 2" 7. HEX 3. Wire Diameter. Wire Type.

Steel Stainless Steel Carbon Steel Silicon Carbide Brass Abrasive Nylon 9. Brown 7. Because there is too much extension cord in use. If too much extension cord is being used, the power supply can be very weak by the time the electricty gets to the tool.

Luckily, charts like the one below show exactly how much extension cord should be used for each tool. Using a tool's amperature rating and the gauge of its cord with this chart will show the length limits for that tool's cord: What to look for: Watch the tool for heat buildup.

Check the tool's amperture rating, the type of outlet being used, and the length of cord in use if there is excessive heat building up in the tool. If the tool has already overheated then the electric motor may already be damaged. An overheated motor may emit sparks , smoke , have a sharp decrease in performance, have a hard time starting up if at all , or all of the above.

For a "Power Cord Repair" articl--Click here. There are different kinds of switches that do this in different ways, but the idea is the same for each kind of power switch. It's worth mentioning one specific kind of switch, the variable speed switch.

Variable speed switches on power tools progress through " steps " as they are depressed more. Each increasing step is usually designed to increase the speed or power of the tool. These switches provide more control to the tool user, but can wear down a little faster. Everyday Wear: When the switch is " off, " the contacts are not touching, and when the switch is " on, " the contacts touch and complete the circuit. For most types of switches this going back and forth between connecting and not connecting creates friction, and wear.

Depending on the frequency of use, most power tool switches will need to be replaced in the tool's lifetime because of simple, everyday wear. What to look for: If a power tool's switch has wear damage it will not complete the electrical circuit when in the " on " position and the tool will not start.

If the damage isn't very bad yet, the tool may start up only sometimes. Wear damage on the switch will not be visible, so the best way to test a switch for wear or other damage is with a multimeter.

Replacing a switch or switch assembly before it gets bad will stop the switch from going out completely. Moisture Damage: The second reason a switch might go out is because of moisture damage. Power switches can short out when water or other moisture gets into the switch assembly. What to look for: Look for sparks in the switch assembly when the tool is switched to " on. After shorting out, a switch will not be able to activate the tool at all and will have to be replaced.

Heat Damage: Many parts of a power tool can be damaged if the tool gets too hot , but the most sensitive component usually becomes damaged first. Sometimes the part of a power tool that is most vulnerable to overheating is the power switch, depending on the tool.

If a tool won't start up after overheating it may be because the power switch was fried. It could be something else , but checking the switch first is a good idea. What to look for: If a switch has been damaged by an overheating tool it will show signs of melting , burning or discoloration when the switch assembly is inspected.

Below is an example of power switch heat damage. In this case, a loose connection generated head and melted part of the plastic switch casing in the circled area: Fried power switches will have to be replaced, but it's a pretty easy and quick fix that will keep the power tool running down the road. For a "Power Switch Repair" article--Click here.

They are almost always retangular or square with one end connected to the wiring coming from the switch, and the other end making contact with the motor. Carbon brushes touch part of the motor assembly called the armature. The part of the armature that carbon brushes touch is called the commutator and is located on one end of the armature usuallly the end closest to the power switch assembly.

Carbon switches are held into place by brush holders which make sure that the brush makes contact with the armature at the correct angle. Brushes also have springs to make sure that the brush applies the right abmount of pressure to the amature when making contact. Everyday Wear: A tool's armature assembly spins while the tool is operating including the commutator which means that carbon brushes wear down naturally with regular use.

Replacing worn brushes is important to maintain a good electrical current running through the tool. What to look for: Worn down brushes will make it hard for a tool to start up, but it will be off-and-on.

One minute it will work fine, and the next minute it won't work at all. This is because the brush is alternately connecting and not connecting with the armature—completeing and disrupting the circuit. Hint: This can look a lot like a power switch failure at first, but if the switch checks out ok which is the right place to start , then a bad or worn brush is the next part that should be inspected. Brushes will normally have a contoured wear pattern on its contact end that matches the contour of the commutator where it touches the armature.

When wear on the brush passes the wear line marked on it, it is time for a replacement. Heat Damage: An overheating power tool will wear carbon brushes down faster and damage the surviving portion of the brush, making it less conductive. The tool will work off-and-on , like with worn brushes, so checking the power switch is the first step in figuring out the source of the problem and what needs to be replaced.

What to look for: Brushes that have overheated can show a few different signs. The first signs of an overheated brush are dark burn marks on the brush itself and a heavy contoured wear pattern. Discoloration can also appear on the wiring connected to the brush. The shade of discoloration can range from silver to copper or gold, depending on the power tool.

See the example of wire discoloration below: Chipping Damage: Carbon brushes are sometimes chipped by a damaged or worn armature. Chips n a brush means that there will be gaps in conductivity when the armature spins, making it so the tool only works off-and-on when the gaps line up just right.

Again, this problem might look like a power switch issue until the switch checks out ok. What to look for: A chipped brush should be easy to identify just by looking at it. If the brush really is chipped, taking a look at the armature for chips is a good idea while the tool is dismantled.

Installing a new brush into a tool with a chipped or worn armature will probably just cause the new brush to be chipped as well. Checking an armature for chips and wear is explained below under Armature. A burr can cause the same problems as other brush issues by preventing the brush from sliding into its brush holder correctly.

Luckily, most carbon brush burrs only need to be filed down a little to be fixed. But a new burr might just form again if the worn armature that caused it isn't replaced.

What to look for: Just look for the burr and file it down. Start with the carbon brushes since they're usually more accessible, and then-- if the brushes check out --take a look at the switch. Tends to Run Fine After Starting Although decreased power can be caused by a bad power switch, it is a more uncommon symptom. Bad switches more commonly tend to have a hard time starting up, but then will run smoothly and at full power once the connection is made.

Brush symptoms tent to cause more symptoms during operation, not just start-up. Off-and-On Use Worsens Steadily Wearing and damaged switches will cause increased off-and-on use as they are used until they eventually don't start up at all. As carbon brushes worsen, the symptoms that worsen with them tend to be during operation.

Off-and-On Use During Operation Several brush problems can cause a power tool to turn off and on during operation as the brushes connect and fail to connect with the armature. Faulty power switches normally will not cause off-and-on use during operation. Shaking or Slapping the Tool Helps Ever had a tool start up after a shake or good smack? This often means it's a carbon brush that's causing the problem, although it can also be a bad armature. Brushes can get caught up in their holders, form burrs, and experience other complications that prevent them from continuously contacting the armature like they're supposed to do.

Shaking or gently striking the tool can sometimes jostle the brushes back into the correct position, making it possible for the tool to complete a circuit.

Shaking and slapping will not have an effect for power switch issues. Banging Sound If there's a banging sound inside the tool's motor when it runs, then it's probably a brush. It could also be a bad armature, but if that is the case then it's most likely that the brushes will have to be replaced anyway.

The banging sound is caused by either a damaged or misshapen brush, or a misshapen armature. As the armature spins, either kind of damage will make the brushes bounce off of the commutator. Power switch failure will not cause a banging sound in the tool's motor.

Eventually, if brushes are not replaced, they can continue to damage an armature and cause overheating or smoke. Sparks and smoke out the vents will not be caused by power switches. It's very important to check carbon brushes often and replace them quickly when they present problems, as damaged or worn brushes can do serious damage to more sensitive and expensive parts of a power tool, like the armature.

Frequent brush checks should be pretty easy since most of them are easy to get to just by undoing a couple screws. Take a look at the switch assembly and check for damage.

Heat damage will appear as melted or discolored wiring, or melted plastic. Below is just one example of switch heat damage: Power switches often wear out with use and just have to be replaced sometimes before they can be eliminated as the cause of a tool not starting. Power switch failure is the most common reason for a tool not to start at all.