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Repair information regarding tools used for a specific task like fixing, building, or cutting. Learn how to use tools that work to fix the ones that don't.

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Sparking around the Brushes

I have a dewalt 4" angle grinder.

It started to spark on one side of the armiture.

Do you know what has happend to this tool?

Answered! View the answer I have this problem too

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i have a HOYOMA 3263T rotary hammer the carbon brushes are burning w/ smoke what happen on this tool?

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I hav an angle cutter of KPT now its sparking a lot and it become heat could not hold and smoke is comes out from the inside.

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dasbishu1986 sounds like a shortened out motor windings. You can take it apart and see if you find some burn marks etc. but you most likely you will need to find a replacement.

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9 Answers

Chosen Solution

If the sparks go all the way around the copper strips, also called the commutator, the armature has shorted. That means the insulation between the wires and the iron has broken down in the inside of the armature. Some times it can be as simple as a short between the bars, the copper strips, of the commutator.

With the tool unpluged, use an air hose with an air nozzle to blow any trash or dust from the area around the brushes and the communator.

If that does not improve the symptoms the next thing is, with the tool unpluged, remove the brushes, often a screw on cap hold them in, and inspect and compare the length. A short length will cause the springs to not put enough pressure on the carbon to make good contact with communtator. In that case, replace the brushes. Also check the freedom of movement of the brushes. If dirt jams the channel the brush slides in, the spring can't push the carbon tight to the commutator.

Good luck!

This repair will work on other hand-held power tools.

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Should the screw on cap be tight or slightly loose on the brushes

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The cap on the brushes should be tight - especially if it is providing the pressure for the contact for the flexible wire from the brushes to compete the electrical circuit..

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  • Step by step guide and via the process of elimination: Cleaning :
    1. First clean the com bars with 1000 sand paper and also the narrow grooves between bars using a blade. Then use a toothbrush to clean any remaining carbon deposit between the bars.
    2. Check the carbon brushes, if they are short, have chips or damaged, replace them with a new set. Also, inspect the comm bars for any damaged or out of the place bar.

* If the above didn’t help, you most likely have a shorted armature (sometimes field coils). To check the armature, first inspect it visually, if you see a burnt spot on wire coils or the spot where a wire is attached to comm bars, that armature is gone. If you don’t see any burnt spots, then you can investigate further using a multi-meter. With the multi-meter set on low ohm, check the resistance of each pair of the adjacent comm bars, the values must be very close, any deviation more than 0.1 ohm is bad. Next measure each pair that are at 180 deg of each other, the values must be close, any large difference points to a problem. You also need to check for a short between comm bars and body & shaft of the armature. There must not be any continuity.

  • If the armature passed the test, the next step is the field coils. You have a pair of wire coils, check their resistance and inspect them for any burnt spot. As before, their resistance must be very close.

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The suggested 0.1 ohm is a rough value. It is correct for winding resistance of around 0.5 ohm.

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May need to ensure zero debris between commutation segments and to use a sharp blade to cut away said debris.

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Working but the corbon bursh is burning

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How to remove the short

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clean the commuter with a sand paper

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No! Use an emery paper 1200 grade.

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I been using 120 grit sandpaper for years with no problems.

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I bought a second hand Hitachi W 6VB2 electric drill it never had a 13 amp plug on it it came with a connector Wat you plug into a transformer so I took that off and put a 13 amp plug on it but when I turn it on it really sparks and crackles so I took it apart cleaned all the comunater and brushes seem fine but still having same problem anyone have any

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This is a 110v piece of equipment and should not be fitted with a standard household plug. Must be run from 110v transformer only.

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The sparking around the comunater usually indicates there is a short between the windings of the armature and ground. If nothing else, check between the individual bars and ground. Also there will be a connection to another bar of the comunater.

I am curious about the transformer: What purpose did it serve? Was this a set up for 220 volts used in Europe? Or perhaps another voltage set up, as yet unknown?

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hi

If your in the UK and you took off the yellow round 3 pin plug and attached a normal 3pin plug you plug straight into the wall. Then you have taken a 110v power tool and gave it 240v.

The short and curly of it is, it will burn out and then all you'll have left is a paper weight.

In hope this helps

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A marble cutter armeture is ok, it's field coil also ok but when operated avvy spark in commutator, where is problem

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I’m having a similar issue with a router. I changed the brushes to no avail. So I inspected the copper commutator bars. One of them is hanging our further than the rest, some sort of wear and tear. It had clear scorch and scoring marks. So, I took some 600 grit sandpaper and tried to sand it flat. That didn’t change much.

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Damon b, your opinion seems useful

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When sparking is excessive from the brushes to the commentator the reason an internal short to ground in the armature. There are few places that can produce a high speed, well insolated armature. Many of the old sources have gone out of business, because the battery powered tools do not use that type armature. The ones available often do not stand up to the use and fail much sooner than the old armatures. If you find a parts house that sells a replacement, ask about a warranty.

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