Brush change in the DeWalt saw

[KarlB]

Has anyone changed out the brushes in their DeWalt saw?  If so, what actions in the saw preceded the change?  Also how long had the saw been in use before changing the brushes? (in years)

I've just ordered some brushes to replace mine which are about 9/16" long. 

Thanks for the replies,

Karl

[DWSudekum]

Carl the motors on the Dewalt generally will short out the armature long before you need to replace the brushes init.  The brushes in my opinion too soft for the use that it is being asked to do.  The carbon dust builds up and shorts out the armature of the motor causing it to fail.  Some of the symptoms are the inability to maintain speed ( speeding up and slowing down on its own ) not starting until you move the arms a bit to get the motor to start.  Sometimes it will just blow the fuse.  The best way to do this is to actually remove the motor from the saw and open it up and blow out the carbon dust and ensure that the armature is clean before you put it back together and then replace the brushes.


DW

[daveo]

Karl
What DW says is correct and a periodic clean will help the motor last much longer
however you say that your current brushes are about 9/16 long, I have just measured a brand new one and it is only about a 1/32 longer than that so am doubting that what ever problem/ symptoms you have are brush related

Dave

[KarlB]

Thanks DW and Dave.

Your advise and insight is well taken.  Too bad I didn't consult here first.  (I probably wouldn't have bought the brushes.)

That being said I guess I'll be taking the saw back apart and doing what you said DW - cleaning out the motor.

...not starting until you move the arms a bit to get the motor to start.

That's what I was experiencing as well as the motor "stuttering".  Since I have a foot pedal I knew it wasn't the switch and the only other electrical I could "relate" to was the brushes.  I've changed out brushes in my Dewalt table saws and miter saws before so I figured - why not?

Getting the saw apart and back together is a pain and sometimes I could use 3 hands!

Any other advise will be appreciated as I won't be taking it apart until Saturday.

I took out my older Craftsman saw but it sucks on the blade clamping system.  I guess I forgot how bad it was before I got the DeWalt.  Can't wait to get "Old Yellow" back in business.

Karl

[DWSudekum]

Karl while you have the saw apart you may wish to put a bit of grease on the moving bearings.  I know they claim to be maintenance free however it still is a good idea.  Look for free floating metal shavings while you have it apart as well.  A good preventative maintenance now and then can keep your saw up for a long long time.

DW

[KarlB]

Yes good tip for greasing everything - I did that last time I had the saw apart fixing something else.

I'll start into looking into the problem tomorrow night.

Karl

[KarlB]

Well I started taking the saw apart and encountered a problem getting the housing off the motor.  I used an impact driver/drill to loosen the screws.

Before this I noticed the motor (under no load) only started at two positions (opposite of each other).  I removed the housing after removing the brushes and cleaned the commutator lightly with 1500 grit sandpaper.  I also flattened out the brushes.

So what's happening now is the motor starts (under no load) at any position, but it is not as fast as I believe it should be.  Plus it is stuttering a bit as it goes round.

Is this because the brushes are now flat and not curved thus decreasing the surface contact with the commutator and thereby having decreased speed?

I am waiting for the new brushes and hopefully this helps.

While waiting for the brushes I disassembled as much of the saw as possible and have cleaned and lubed the needle bearings where I could get to them.  I noticed a couple of the sleeves could be replaced.  I could not get to a couple of the bearings unfortunately.

I did get some help from Bob Brokaw's (Gwinnett Woodworkers) videos on Scroll Saw Maintenance on YouTube.  This is good information even if you don't plan on doing your own maintenance.

Karl

[KarlB]

I received my new brushes today and have started putting things back together.

(One word of wisdom here.  It's best if you disassemble and reassemble the saw within the same day.  Since my memory "ain't what it use to be" I had to keep consulting the exploded view to put things back in order!)

First as Dave noted the new brushes were only 1/16 longer than my old ones and that's probably due to my sanding of the old ones.

My next problem after putting the motor back together and turning on the switch - it through the breaker.  Back to disassembly of the motor again.  Low and behold there was a wavy washer half mangled near the armature of the motor.  Not exactly sure where it came from as the one that goes around the main bearing is still in my parts cup.  I believe it went between the motor housing and the lower sealed bearing.  So I put it there and tried again - no success. (BTW, the lower bearing spins a bit rough and probably should be replaced.)

I then removed the wavy washer from the motor and tried the motor without any thing connected and finally got it to work by moving the motor around again  - same problem as before.  So I reattached the upper and lower arm assembly and temporary screws attached to try the motor with attachments.

Well again it would only work if I moved the arms up or down.  It will constantly run like this, but it has stutters still.  It seems to me this is still electrical in nature.

I'm starting to run out of options.

Any advice anyone?

Karl

[Norm Fengstad]

I suspect there is an armature issue, or one of the field coils is lazy. If the armature has a shiny section it may be rubbing on the field coils. or, there could be broken winding wires hidden inside the coils, worn out bearings could cause this condition or the crushed washer you found may have damaged the windings. An electric motor rewind shop would be able to diagnos this. to fix that would be a new motor. A new motor from Dewalt would probably be quite pricy..

[KarlB]

Thanks Norm for the tip. 

I took the motor to our local armature works.  Bench charge is $32.50 but will be applied to any repair if wanted.  Will find out next week.

Karl

[Norm Fengstad]

Glad I could help. Happy Scrolling

[DWSudekum]

Thanks Norm for the tip. 

I took the motor to our local armature works.  Bench charge is $32.50 but will be applied to any repair if wanted.  Will find out next week.

Karl

A new motor for that saw is in the $285 dollar range last time I looked.


DW

[KarlB]

A new motor for that saw is in the $285 dollar range last time I looked.

Yeah that's what I'm afraid of - a new motor.  I'm watching one on Ebay for $140 and an online parts supply is $296 (both plus shipping).  I'd be hesitant on the first one and not likely on the second. 

At $300 for a new motor I would just buy a new machine and save this one for parts.

I'm pondering at what price point on repair or replace do I repurchase?

Karl

[DWSudekum]

Dewalt has a Guaranteed Repair Price program- somewhere around $270 if memory serves me correctly.  I used that when my motor died and had them do a complete overhaul and tune up on the saw.  I would only do it once though.  Next time is a new saw and this one will be parts. 

The other thing I have been contemplating is modifying the saw ( after the motor dies ) and make it a direct drive belt system.  I have the parts and the knowledge to do it... just a matter of wanting to hehe.

DW

[KarlB]

Dewalt has a Guaranteed Repair Price program- somewhere around $270 if memory serves me correctly.  I used that when my motor died and had them do a complete overhaul and tune up on the saw.  I would only do it once though.  Next time is a new saw and this one will be parts.

The other thing I have been contemplating is modifying the saw ( after the motor dies ) and make it a direct drive belt system.  I have the parts and the knowledge to do it... just a matter of wanting to hehe.

DW

Are you saying DeWalt would repair for that amount?  And I guess if only under warranty still?

I thought the same thing for the old saw.  I don''t have the parts or knowledge, but I did watch McGyver a long time ago.   Actually I could probably figure something out, but I want to get back on the saw sooner than later.  I looked again at my "backup" craftsman to see if I could modify the blade holder, but it will take changing their clamping system.


Thanks DW.

Karl