Replies

1. 
   Frozen | Jul 21, 2004 07:10pm | #1

   I have a PC router that I could always see sparks through the vents, right out of the box. I aways assumed that it was normal, and it's worked fine for 10 years. It never worried me until your post!

2. 
   JohnWW | Jul 21, 2004 07:17pm | #2

   Forestgirl

   If you take a look at any of your small power tools when they're running you will see some sparking, so sparks alone don't indicate trouble.  Some tools just spark a lot more than others for no obvious reason but they don't wear out any faster or perform any differently. 

   The fact that the tool is barely used may just mean that the brushes haven't broken in yet or there is light oxidation on the commutator's surface and the brushes will spark more than usual until the motor has been run for a few hours. 

   As long as the brushes aren't worn out and the tool is working well otherwise, I wouldn't worry about it.  You might check the brushes again after a couple of hours running time, if the brushes are wearing quickly then you might have a problem with the commutator surface being rough and that would need repair.

   Hope this helps, John W. 

3. 
   Midnight | Jul 21, 2004 09:39pm | #3

   FG..

   Like the guys have said, it's normal for a brush type motor to spark while running. If it's sparking excessivly, it's possible (but highly unlikely) that the mica that insulates the comutator segments may need cutting back a little; this would only need to be done if there's a pronounced groove of wear in the copper segments where the brushes run. I'd remove the brushes, lightly brush out any stray carbon around the commutator, give it a light spray with a degreasing solvent and replace the brushes. The only time to worry about it is when the power seems lackluster. It'll be fine; Hitachi's are generally built like the proverbial brick privy.

   Mike Wallace

   Stay safe....Have fun

1. 
   forestgirl | Jul 22, 2004 12:18am | #7

   Hi guys, thanks for the reassurances (Steinmetz notwithstanding, LOL -- more for him later!).  This is the router that lost out in a bid for "Which router do we give to the son/step-son?" as he got the Makita plunge router.  Now that summer retail has slowed down, I'm gazing around for stuff to put on eBay, but I don't want to auction a bum tool.

   I'll run it awhile, see if it breaks in, or as Steinmetz fears, shows symptoms of a serious problem.  It's an older model, 1/4" collet only, and if I'm lucky I'll get my $$ out of it.  If not, it's not a huge loss.

   Thanks again!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

1. 
   SRToolguy | Jul 22, 2004 06:03am | #8

   You've been given some good advice and most likely it is all correct. There is some normal sparking between the brushes and the commutator because at speed the brushes are not actually in contact with the commutator but instead riding on a cushion of air just slightly above. The electricity that is entering through the brushes is seeking the shortest path to ground (the commutator) and literally jumps from the brush to the commutator. The jumping electricity is burning up the air (roughly speaking) between the commutator and the brush and that's what you are seeing. Yep, you guessed it, you have your own little lightning storm going on inside that puppy.

   OK, so much for that.  If there is excessive arcing between the commutator and the brush it is usually caused by an abnormal increase in the distance between the brush and the commutator during run time. Three things play in this equation; 1. The commutator is rough or out of round; 2. The armature bushings are shot and the armature is wobbling; 3. The brush springs are weak.

   The easiest test is to replace the brushes and see if the problem goes away. If not then you need to have the commutator checked. When you do the commutator check also check for side play in the armature bushings. Simple stuff and shouldn't cost you more than a couple of bucks.Sincerely;

   The Tool Guy

1. 
   KeithNewton | Jul 22, 2004 06:42am | #9

   Tool Guy has given the best advice IMHO. But I would like to add. I have had some of the little commutator segments get a little loose, and have had their trailing edges erode a little, which may be an indicator of other problems, but if you can get one there is a little ablative commutator stick which you touch the commutator while the motor is running which will dress and seat the brushes if they are ####little out of round. If you can't get one in there, you can take the armature out and mount it in your lathe and dress it there.

   A bad top bearing can cause enough run-out to cause this.

   If it is only one brush, it would be none of the above.

2. 
   forestgirl | Jul 22, 2004 06:25pm | #12

   Hey Tool Guy, thanks for your response!  A question:  Of those things you describe, which are the most likely in a router that hasn't been used very much at all (or maybe never) and was kept in dry storage?forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

4. 
   jako17 | Jul 21, 2004 09:40pm | #4

   Hi there  F.G Sparks are normal as long as they are not excessive,under load they may get a bit more pronounced.Run the router a few minutes and make sure that the top and bottom  bearings are not over heating(warm is ok ,hot is not).Also that there is no play in the armature  shaft.Otherwise don't worry

1. 
   GrGramps | Jul 21, 2004 11:34pm | #6

   You are probably looking down at the router as you use it, and the lighting in your shop is not as bright as sunlight.  Put it in a router table or move outside in the sunlight and you won't see the sparking which I see in my Porter Cable routers and in my Dewalt miter saw.  I would be very surprised if I couldn't see sparks in a brush type motor, even at my age.

   Roy

1. 
   forestgirl | Jul 23, 2004 04:54am | #14

   Bowing to Gramps' wisdom (#7 above - <grin>), I re-tried the router after replacing the lights in one of my fluorescents and adding a new fixture the other night.  Amazingly enough, I hardly noticed the sparks when running it in decent light.

   PS:  The lighting improvements were done independent of the router troubleshooting....really they were!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

5. 
   Steinmetz | Jul 21, 2004 11:27pm | #5

   Hey Gurl, I'm not trying to worry you, but if the sparking is excessive, it MAY indicate a 'Shorted winding'

   Each winding on the armature is connected to the segments on the commutator

   It is quite possible for the motor to run on less windings but, alas, putting out less power. (And more sparking.)

    If, for any reason the tool stops ( when the switch is in the on position,) DON'T put your fingers near the router bit.

   Any knock/bump/or vibration will cause the armature brushes to contact a good segment causing the tool to start again.

      It will run and stop again with this problem, but invarially it'll stop on a 'Dead' segment again and refuse to start .

    Deep six that puppy Stein

   
   

   ---

   Edited 7/22/2004 5:09 pm ET by steinmetz

6. 
   nikkiwood | Jul 22, 2004 08:15am | #10

   I am a mechanical idiot. If I had such a router, and was concerned about the possibility of excessive sparking, I would haul it around to a repair center, turn it on and let those people judge.

   If it is okay, you're out the door in 5 minutes. If not, they will either sell you the necessary parts, or fix it for you.

1. 
   forestgirl | Jul 22, 2004 06:21pm | #11

   >>"If it is okay, you're out the door in 5 minutes."   Yeah, but I'd be missing all this fascinating conversation about commutators and armatures, LOL!

   OK, I may very well take it into the little Electric Shop, but I couldn't fit it into my schedule early this week (they're in a town 20 mi. away and have somewhat short open hours).  In the meantime, I'm learnin' some stuff here.   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)Another proud member of the  "I Rocked With ToolDoc Club" .... :>) 

7. 
   ackkacilliac | Jul 23, 2004 04:23am | #13

       I have a badly abused Makita  half inch tha t a guy gave me to fix because of severe arcing at the brushes.

      The field coil windings were shorting due to burnt insulation which caused severe orange fireworks displays at the brush/comutator,  compared to minor blue sparks which is normal.

     fwiw,

   Ken