Class 25/33: Step 4 – Cleaning the Commutator

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  • Gripping the armature and shaft assembly as shown in picture 1, the left index finger and thumb are gripping one of the drive coupling springs. With the right hand, gently rotate the armature anti-clockwise so that it releases (not grips) the shaft. It will only release if you rotate it in the correct direction. Do not persistently rotate in the wrong direction, and do not try to “pull” the armature out of the spring – both events will damage the drive coupling spring.
  • The only part of the motor that should need cleaning is the commutator. With the motor free of all bearings and drive coupling springs, take a soft artist’s brush, cut it down to approx. 5mm and brush in between the commutator slots. Cutting the brush down makes the bristles stiffer. Do not use any metal instruments in an attempt to clean the commutator, no matter how stubborn the deposits. Metal will scratch the commutator and you do not want this. Also don’t be tempted to slide a blade into the commutator slots to clean them – you could dislodge a commutator segment from the shaft. I learnt the hard way as that’s exactly what happened to me. Notice the very fine wire soldered on to the collar of the commutator and be sure not to damage this. It’s best to keep everything clear of this area.
  • Lastly, with a lint-free cloth soaked in isopropyl alcohol (IPA), wipe the commutator surface as in picture 3. Using lint-free materials is important, since you do not want to get fibres wrapping around the shaft or commutator.

 

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