Kirby Sentria Questions...Please Help !!!

[secretstallion]

Hi, I have joined this forum to hopefully get some questions answered by some really clever Kirby people. So I hope that you are out there guys!!!

1. I believe that new carbon brushes are about 20mm long.
At what point is it recommended to replace them?
I have seen various lengths given but i think it is when they are worn down to
between 1/4 inch (6mm) - 3/8 inch (9mm). Can someone give me the correct answer.

2. When reseating these new carbon brushes with a Martindale Diamond D brush seater stone, how many seconds does it usually take to get the commutator curve fully on the carbon brushes?
Once that is done, do you then run the motor for a while to finish the seating process?
If so, how many minutes?
I understand that the end goal is to go from a lot of sparking to a small blue spark / arcing between the commutator and the carbon brushes.

3. This is regarding the armature bearing in the front bearing plate.
When replacing this bearing, what is the minimum recommended specification
for this replacement? ie. ABEC-5...C3...etc.
Also, do I replace with metal shields (ZZ) or rubber shields (RS).

4. This is regarding the armature bearing at the rear of the motor housing.
When replacing this bearing, what is the minimum recommended specification
for this replacement? ie. ABEC-5...C3...etc.
Also, do I replace with metal shields (ZZ) or rubber shields (RS).

Thanks
S

 

[chicagomike]

1. Replace them when they are almost completely gone.. Or replace them when you think they are too short, they are cheap in cost to replace.

2. Run until it is clean and then turn on machine, and look at the spark, if still arching, then use the stone again - and make sure to vacuum or blow out the dust from the stone. P.S., it only takes seconds not minutes...

3. Buy the bearing from a Kirby dealer, then all the rest of your questions are not applicable. Regarding other parts, if other parts are damaged then replace - or if you want just replace all the parts as the remaining parts you mention are inexpensive.

4. Buy the bearing from a Kirby dealer, then all the rest of your questions are not applicable.

 

[secretstallion]

Hey Chicagomike,
thanks for your reply.

Regarding question 2, you started with 'Run until it is clean'
Can you explain exactly what you mean?
I am guessing this means either:
1. Apply the stone for a few seconds until the sparking between the commutator and the carbon brush reduces to the normal light blue spark.
Or
2. Apply the stone for a few seconds which should result in the carbon brush having the curve of the commutator on it.

Kind Regards
S

 

[chicagomike]

Apply the stone for a few seconds until the sparking between the commutator and the carbon brush reduces to the normal light blue spark. - it does not take long regarding time - seconds for most and some a little longer - in a well lite area, apply stone for 3-4 seconds, vac up the dust, and then turn vac back "on" to look at the spark. Or if you are doing this in a dark place with not much light, then you can see as you grind how the spark is changing.

 

[secretstallion]

Hey Chicagomike,
thanks for making that really clear for me.

Because I have not yet seated brushes, there is just one final piece of information I need to know.

Those 3-4 seconds of using the stone, does that:
a) Put the commutator curve across the full width of the carbon brush?
OR
b) Put the commutator curve across a partial width (centre) of the carbon brush? And then the rest of the width of the carbon brush will be completed during normal use of the vacuum.

Kind Regards
S