Rainbow D4C SE motor reassembly after repair - doubt

[johnmalkovich]

Good morning to everyone, this is my first post on this forum.
I have been a happy owner of Rainbow D4C SE since 1997, which now I overhauled for the first time. Replacing bearings and brushes was part of the work. While putting the motor back together, I followed both the technical drawings and the photos which I had taken at every step while taking it apart.
Now, everything is put together but before I power it up, here is my concern: when I spin the motor shaft by hand, there is a slight rattle inside the vacuum chamber of the motor, where aluminum fans are. I can also hear that at least one fan will briefly continue to rotate or slip after the shaft has stopped. When I shake the motor,I can also hear very slight rattling of fans inside. Is this normal? Looking at the schematics, I don't see that the fans are tied to the motor shaft, so they can only be loose, in my understanding.
Thank you in advance for your help and advice.

 

[bikerray]

Did you replace all 3 bearings in the motor and fan housing?

When you put the motor back together did you make sure that all the fans, washers and spacers were in the correct order?

If you left all the fan assembly in the housing and just pulled the armature out, one of the washers could have slid out of place and in between the fan blades.

Next question did you tighten the nut at the end of the spider to lock everything in place?

 

[johnmalkovich]

Hello bikerray,

Thank you for your advice, tightening the nut at shaft end solved the issue. I actually wanted to test just the motor without bottom assembly before putting it back in the housing and I thought the nut would only hold the spider. Everything is fine now. Thank you again.

 

[johnmalkovich]

On power-up, I am getting sparks between brushes and armature. After one minute of running, the commutator already turned darker and the upper motor part got hot.
As I have no access to original brushes which are two-part, I replaced them with single-block brushes of identical dimensions. The commutator was previously cleaned with fine sand paper. I also did run fine sanding paper between new brushes and commutator to shape brushes faces and help them seat in. I also did check the rotor coils with multimeters and I am measuring 1,2 Ohms between adjacent contacts on commutator. Any advice? Thank you.