[Narly1]

When cutting commutators, what is a minimum practical diameter to adhere to?

Also, what factors affect this value?

My intuition tells me that RPM, spring tension and whether the brushes are stand-up or lay-down style would all need to be considered.

Thanks in advance for the info!

Narly1

[Bdegan2]

I once heard that as the comm diameter gets smaller, the rpm's will increase but the power will go down. Similar to advancing the timing.
It is a downward spiral. As the rpms increase so does heat on the comm lending to a shorter interval before the next cut is needed.

"endler" would be able to tell us where the point of no return is.

[imported_offroaders]

ok i know i am going to be told this is wrong but any way

i took my motor and tryed it but i needed to cut the comm so i took fine sandpaper and put the one end of the motor shaft in to a drill and then spin it and drag the sand paper on it till its shinny
i am not saying this is right but i tryed it and it works wayyy better then before i did it

[Bdegan2]

There is nothing wrong with what you did.
The wear on your comm may not have been too bad.

Once things get to a point. Only a cut on a lathe will bring it back so everything is nice and flat across the comm and the brush can seat and make full contact.

[Bdegan2]

Hi Earl,

I posted your question on another forum. Got alot of answers.
The most informative was form duckman right here.

Here is the link, it is a good read.....
http://www.rctech.net/forum/showthread.php?t=157992

[Narly1]

Originally Posted by offroaders

ok i know i am going to be told this is wrong but any way

i took my motor and tryed it but i needed to cut the comm so i took fine sandpaper and put the one end of the motor shaft in to a drill and then spin it and drag the sand paper on it till its shinny
i am not saying this is right but i tryed it and it works wayyy better then before i did it

That is what I did with one of my own motors when I was just starting out and before I got a lathe.

We all do the best we can with the resources available!

Hi Earl,

I posted your question on another forum. Got alot of answers.
The most informative was form duckman right here.

Here is the link, it is a good read.....
http://www.rctech.net/forum/showthread.php?t=157992

Hey thanks Brad, (and Duckman) that is exactly the kind of answer I was looking for.

Now that I also have that dyno I can observe the change in performance vs comm dia. as I go along and actually learn something!!

Thanks again,

Narly1