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Old 05-03-2007, 02:19 PM   #1
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Default MOTOR COMMS

Hi can some help me.

Everytime I cut a comm on my new integy lathe with a diamond bit, my motor drops in rpm's what am I doing wrong.

Is there a thickness of the comm, that once you reach this it is no good?(as the motors I have tried are second hand haven't tried my good ones yet)
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Old 05-03-2007, 02:31 PM   #2
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Do you replace the brushes with new ones or atleast re-serrate the worn brushes?

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Old 05-03-2007, 02:38 PM   #3
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Well it all depends on how much you are taking off the comm. Try cleaning out the motor can put fresh brushes and re time the motor. It sounds to me that it's not the comm its the brushes. Brushes tend to get carbon build up which decreases current and lost of power. Try to clean up your brushes too. I do alot of electric dragracing and after every pass I cut the comm clean up my motor can and freshen up my brushes and sometimes replace my motor springs. For cleaning the motor can use contact and curcuit board cleaner and spray this stuff in the motor can and use it on the arm. too. I've been doing this for years and every time my motor runs it runs 100% until the comm has no meat left on it and the magnets on the can go dead you can get alot of life out of the motor if you keep on top of it. I hope this helps you and if you need and more help I will be glad too help and just FYI when you cut the comm don't take so much off of it use a black permenant marker color the whole comm in marker and start the cut lightly and if you still have marker or scorch on the comm keep taking it down lightly until its completely clean and looks new. Good luck...
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Old 05-03-2007, 02:38 PM   #4
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Quote:
Originally Posted by Charles Godwin
Do you replace the brushes with new ones or atleast re-serrate the worn brushes?

Charles
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Old 05-03-2007, 02:42 PM   #5
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And don't forget to lube up the bearing's...
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Old 05-03-2007, 03:02 PM   #6
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Yes I use 4499 brushes.
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Old 05-03-2007, 03:49 PM   #7
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should the brushes be replaced every cut and how offen do you do a cut?
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Old 05-03-2007, 04:15 PM   #8
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If it's a club race and there's time between rounds to do a full rebuild (skim, clean etc) maybe 1 cut per night. 1 before you go to the club to race then maybe 1 after 3 runs. Brushes, if they aren't discoloured (purple) but have the serrations worn off just reserate them then run the motor back in with a drop or 2 of bushing/bearing oil on the bushings/bearings. If they are coloured replace them with new brushes then run the motor in. One thing to try is cutting the trailing edge off the brushes. For me i get less wear on the comm by doing this.

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Old 05-03-2007, 04:59 PM   #9
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Quote:
Originally Posted by Charles Godwin
If it's a club race and there's time between rounds to do a full rebuild (skim, clean etc) maybe 1 cut per night. 1 before you go to the club to race then maybe 1 after 3 runs. Brushes, if they aren't discoloured (purple) but have the serrations worn off just reserate them then run the motor back in with a drop or 2 of bushing/bearing oil on the bushings/bearings. If they are coloured replace them with new brushes then run the motor in. One thing to try is cutting the trailing edge off the brushes. For me i get less wear on the comm by doing this.

Charles
you have time to rebuild a motor at a club race
your lucky
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Old 05-03-2007, 06:32 PM   #10
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Quote:
Originally Posted by Charles Godwin
If it's a club race and there's time between rounds to do a full rebuild (skim, clean etc) maybe 1 cut per night. 1 before you go to the club to race then maybe 1 after 3 runs. Brushes, if they aren't discoloured (purple) but have the serrations worn off just reserate them then run the motor back in with a drop or 2 of bushing/bearing oil on the bushings/bearings. If they are coloured replace them with new brushes then run the motor in. One thing to try is cutting the trailing edge off the brushes. For me i get less wear on the comm by doing this.

Charles
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Old 05-03-2007, 06:32 PM   #11
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Quote:
Originally Posted by wallyedmonds
you have time to rebuild a motor at a club race
your lucky
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Old 05-03-2007, 06:45 PM   #12
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So when the brushes turn black replace them?
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Old 05-04-2007, 02:15 AM   #13
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bump
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Old 05-04-2007, 03:36 AM   #14
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If the brushes are the colour they started out as (copper type colour) then you should be able to re-use them as long as you re-serrate them (if there are no serrations left). If there is any purple then you should replace them. If the brushes look black then you should be able to wipe the black stuff of with a cotton bud or cloth. If it doesn't come off, replace them just to be safe.

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Old 05-04-2007, 06:36 AM   #15
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If the brushes are the colour they started out as (copper type colour) then you should be able to re-use them as long as you re-serrate them (if there are no serrations left).

When you say to re-serrate them, how is this done?
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