Video of excessive sparking in PC router

[betacrash]

I recently changed out the brushes and bearings in my 7518 router. I ran is for 30+ minutes at 10000 RPM's to break it in. It was running great. Low noise and no sparking. I was getting ready to cut a new project since the change out noticed that when I set it to 19000 RPMs the thing sounded like it was going to explode and the sparking was crazier than I had ever seen on it before. What is up with this thing? If you listen on the video you can hear the fluctuation of speed as well. If anyone has any ideas on what the problem might be I would love to hear it.

http://www.youtube.com/watch?v=I8hyxhLQnM4

[myxpykalix]

not sure what the exact problem is but watching the video, i thought i was in Dr. Frankensteins laboratory with all the sparks flying the way it was.
This is only a guess based on little knowlege but it seems to me that it might be that the brushes are not set with the correct distance and the spark has to jump further to make the circuit kind of like if you have a spark plug set with a wide gap the spark will be weaker by the time it hits the post even though it might only be thousandths of an inch.
That might be the reason for the fluctuating rpms also.

[srwtlc]

You may have a shorted armature or loose commutator bar. Maybe try reseating the brushes. Also, if the commutator is badly worn, you may not be making good contact. You might be able to get it turned down.

[betacrash]

One thing I noticed when removing the armature is that there was a slight groove on the armature where the brushes were. I wonder if it is no longer lining up with that groove and causing a gap problem. I was really hoping that my first youtube video would have been cooler than that.

[paul60]

I have the same problem with my milwaukee router
lots of sparking. i thought it was the brushes so
i replaced the brushes but no change
in the end i replaced it with the original router
i was using. a MaKITA.
The commutator looks good dont show any wear.
paul

[dana_swift]

The sparks are white hot material flying off the contact point. Its either metal from the commutator or carbon from the brushes. Look inside again and see which is showing the wear. Check the assembly, something isn't right. Missing springs?

Normal arcing is caused by the inductive kickback of the motor when the circuit is broken to an individual field winding, so there must be some contact to get the current going through the winding, but that contact overheats from lack of surface area. Which side is eroding at what rate is the question.

I dont know how the brushes are held inside the PC router but perhaps the pressure springs are not set right?

I have an aging PC router myself, after watching this video I have wondered if a new router would be a better option than a fire.

Good luck-

D

[betacrash]

I broke down and took it to a local place that repairs porter cable tools. Found out that the armature was totally jacked. So $189 later it is working like new.

Cause of issue-
If I would have only replaced the brushes I may have not had such noticeable failure since the brushes probably would have fit right into the worn groove that the previous brushes made. But since I changed the bearings also it caused the brushes to not exactly line up with the worn groove causing the spectactular show that you see in the video. Still the armature needed to be replaced. oh well.