Repair Noisy Bearing Angle Grinder

Memperbaiki Gerinda Tangan yang Bersuara Berisik karena Bearing Rusak

Noisy angle grinder, and quickly getting hot: are most probably caused by spoilt bearing. The balls inside the bearing run randomly without guide.
There are 3 bearings inside an angle grinder. Two are located inside the gearbox. The other one is after carbon brush area. Following instructions are more useful for the 3rd bearing.

Repair Steps

1. Hunt for your tool's parts breakdown schematic.
     This parts breakdown provides useful information about the structure of the power tool, and part numbers (if you need to replace some part(s))

    Example for Makita 4" Angle Grinder (GA4030):
    https://www.partswarehouse.com/Makita-GA4030-4-Angle-Grinder-s/323873.htm

MK-GA4030 4. Ball Bearing 607Llb MK-210034-7 5. Insulation Washer MK-681636-0 6. Armature Assembly, Inc. 4,5,7 115V MK-517646-0    .    ..    ... 40. Brush Holder 6X9 MK-643839-4 41. Carbon Brush Cb-458 MK-194721-5    .    ..    ... 2. Open the grinder lock nut using the lock wrench 3. Remove the safety cover Unfasten the screw locate the locking protrusion and pull the safety cover out 4. Unscrew the back-cover  5. Release the carbon brush' pressing spring.    You can use any thin mild strong tool (for example small screwdriver, bamboo stick, tweezers,... 6. Pull the carbon brushes out and release the crimp connections     I used long nose pliers to pull out the crimp. 7. Unfasten 4x PH2 screws which join body and gearbox together 8. Pull the gearbox away from the body. You may need to use slot screwdriver bit to spudge the gearbox away. NOTE: not to puncture too deep until breaking the fan blades inside. 9. Pull the broken bearing away from the armature assembly. The best is using bearing tracker. Or you can use 7mm spanner, hold it below the bearing bore, while knocking a Ø5-6mm bolt downward to the armature shaft. knock it gently. Broken bearing: Search for same bearing type as per the schematic: 4. Ball Bearing 607Llb MK-210034-7. The important thing here is searching the same size and type bearing. The original bearing is "sealed" type, which will be very crucial in preventing dust penetration into the bearing, and in turn destroying the bearing. Here is example of "double sealed 607 bearing" (607RS) 9. Knock in new bearing to the armature assembly. Use hammer to knock the bearing gently and evenly. You can also use back the 7mm hex spanner hole to push on the bearing bore evenly. Knock as close as possible to the armature shaft for accurate bearing down sliding. 10. Install every part back and ensure repair is effective. Non Commercial Share-right: Some images and contents of this page are retrieved from ifixit.com because I missed taking some photos during my grinder repairs. They are non commercially shareable with proper credit under the Creative Commons Attribution Noncommercial Share Alike license.

Replace Slim Angle Grinder Carbon Brush

If your power tool (angle grinder, drill, sander, etc.) starts intermittently getting hot, not having full speed or full solid rotation during use: you may need to take a look at the carbon brush condition.

If the carbon brushes are too short, they don't have sufficient length to reach the motor commutator and will not be able to perfectly make contact with the commutator.

Above photo depicts worn out carbon brushes on top, and new carbon brushes on the bottom. For carbon brushes with copper braids on the side like these, the copper braids will restrict the carbon brushes to go all the way toward the commutator, because the copper braids will get caught by the brushes metal compartment. This is the reason, above "worn out" lengths still showing some carbon thicknesses that are actually wasted (about 3 - 4mm wasted thickness).


Repair Steps

1. Hunt for your tool's parts breakdown schematic.
     This parts breakdown provides useful information about the structure of the power tool, and part numbers (if you need to replace some part(s))

    Example for Makita 4" Angle Grinder (GA4030):
    https://www.partswarehouse.com/Makita-GA4030-4-Angle-Grinder-s/323873.htm

MK-GA4030 4. Ball Bearing 607Llb MK-210034-7 5. Insulation Washer MK-681636-0 6. Armature Assembly, Inc. 4,5,7 115V MK-517646-0    .    ..    ... 40. Brush Holder 6X9 MK-643839-4 41. Carbon Brush Cb-458 MK-194721-5    .    ..    ... 2. Unscrew the back-cover  3. Release the carbon brush' pressing spring.    You can use any thin mild strong tool (for example small screwdriver, bamboo stick, tweezers,...

4. Pull the carbon brushes out and release the crimp connections
    I used long nose pliers to pull out the crimp.

5. Source for replacement carbon brushes. 
   The exact part for MAKITA GA4030 is CB-458 (6mm x 9mm). However I could not find this exact part. I decided to purchase CB-459 which is pretty similar in size, just a little difference at the crimp. I expanded the crimps a little bit for them to be able to plug to the male connectors.

6. Close back everything with the same tools and reversed step sequence.



Non Commercial Share-right:
Some images and contents of this page are retrieved from ifixit.com because I missed taking some photos during my grinder repairs. They are non commercially shareable with proper credit under the Creative Commons Attribution Noncommercial Share Alike license.

Repair Malfunctioning Car Horn

Indonesian: Memperbaiki Klakson (Bel) Mobil yang Tidak berfungsi
Case in: Daihatsu Ceria (Cuero)

If your car/motorbike horn is not functioning, you may want to try this troubleshooting.

1. Open machine bay cover
2. Push the horn button, and hear if there is relay "click" sound activating from the machine bay. 

 1). If there is no click sound, the malfunctioning part could be either the horn switch in your steering wheel or your relay is broken. You can confirm this using multimeter (Ohmmeter) measurement.

• Good switch shall be short circuit (around 0-4 ohm) when being pressed. See picture below on how to reach the switch. Open the screw behind steering wheel.

• Good relay coil shall have some resistance when being measured using ohmmeter. If it is read 0L (zero load), it is broken.

Less costly way to confirm all above is by short circuiting the correct trace.
To confirm whether the switch is broken: short circuit the both 2 switch terminal. If your horn beeps: the switch is broken. You can consider to replace or try repairing it. For myself, I have ever dismantle the switch and repair it by myself. It is always about misplace or dirty contact. Once the placement and/or carbon/dirt are rectified, it worked.

To confirm whether the relay is broken: 
a) Open the relay cover
     

b) Short circuit the relay switching terminal (push red arrow metal below using screwdriver towards blue arrow metal). If the horn beeps; your relay coil is broken. Replace the relay with the same current amperage rating.

   2). If there is "click" sound when you press the horn switch: either your 

• Loose wiring between relay and horn. Check if your horn lugs/crimps are tight. They are usually full of dust/soil if used to drive in harsh environment. Spray contact cleaner and scrape the dust/soil if necessary.
• Broken horn. Test this by supplying Battery+ wire 12V directly to your horn terminal. If it doesn't beep, replace your horn.
• Relay actuator fails... see following photo, there is black carbon/burnt residue disturbing the contact, and the contact circle is already thin. 

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At this point you may consider to directly replace the relay with new good one. For my case, I prefer to extend the life for longer time. I clean away the carbon/burnt residue, and re-shape the contact circle.

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