235: Sunday 15th July 2012

Today my back is really sore and last night it was worse. I don't know what caused my back problem, but I have not been able to do anything today. So I edited the video that I made. Yesterday I re-cut the grooves in the motor commutator and it should be ready to go back together. I made a special tool by grinding the edges down on a Phillips screwdriver using my bench grinder. I was using a junior hacksaw blade and it was taking forever and making my fingers sore. The new tool was much quicker and less likely to slip out of the groove. The ends of grooves were easier to finish up to. The photo below shows the finished commutator. I am not sure how to test this as all the com segments measure 0 resistance to the next one. I can see the grooves are clear right to the ends. I cannot trace out the coils as they disappear inside the rotor and I cannot figure where the come back out. Am I doing something wrong? It is like the rotor has one continuous winding that exposes all the loops at the commutator.
This video shows the process I used and the tool to clean up the motor rotor grooves on the commutator.


  1. The winding is a loop that goes around....
    thats right! You will measure zero!
    in earlier time this was measured with some
    beeper like a doorbell that changed its tone.

    .....i told You not to do this at home! ;-)

    I hope, Your back will be ok again soon!

  2. Thanks for the confirmation. Next time I come across a problem like this I shall give the motor to a shop to repair. It is a lot of work to save just a few bucks and while my electric car is off the road I am having to buy petrol, so in the long run I could have motor back on now, no back ache and be saving money. I hope someone else can learn from all my mistakes here. At least this is a good example of whether it is worth doing the work. For me the answer is NO. I have a much deeper knowledge of the motor now and some good photos of it all in bits. I believe it is a good experience, but not worth doing unless it is a hobby. For me this is a hobby, but once is enough!