14 inch milwaukee chop saw just quit!

[toplessHO]

Well its been a couple years since it was used
stored in conex out back on a shelf.
I turned it on and sounded weak.
shut it off and it now does nothing.
I thought maybe the cover on the back of motor was to access brushes but none were under the cover when I removed it.
Ive used my ac voltage detector pen to verify its getting power past the switch and to one side of the motor.
But that wont check for a neutral connection.
Any ideas on what fails on these?

 

[Dingleburry]

The brushes are usually on the sides of the motor. Not under the motor cover. AFAIK
The black caps on this one. Just unscrew.

 

[2oolhound]

Sounds like brushes alright. I've found a lot of times the brushes are not wore out and cleaning the armature works good. If you re-use the brushes sometimes the arc of the armature wears more on the top or the bottom so you want to mark the brushes when you remove them so they fit nicely when you re-install them, keeping them in the same orientation..

 

[Dingleburry]

Check the face of the brushes also for pitting or burns. They should be smooth and shiney. They will prob have grooves in them as well. Which is fine. If they are burnt, you can try sanding them carefully keeping the contour in them. If this is the case they prob wont last long. But may get you through a job in a pinch. To clean armatures, they make stones for that, which is what i always use. But im sure fine emery cloth or scotch brites would work too. Also ive seen DC motors not run from the carbon dust build up. Give it a good blast of air to clean out all the carbon. And after cleaning armature. When im done cleaning armature i always blow it out then spray down with non conductive non flammable solvent.
Also there may be brush material left, but also too short so theres no spring pressure pushing them against the armature. Ive also seen some that break contact when they get to a certain length.
Aditionally inspect commutator bars and windings for burns.

I take it you dont have a DMM?

 

[toplessHO]

pics attached
mines not like the one pictured with black caps
removing the cover,where it appears the brushes should be ,gets you no where

 

[The Cobbler]

sure looks like there would be brushes under that end cap.
got a model number?

 

[Dingleburry]

There under those round parts in the cover
That a 6175?
ereplacementparts have brushes for like 4$ assuming its a 6175

 

[evintho]

Yes, they are there. Here's my restored 6175.
Pull the 4 screws at the louvered rear cover and remove...…



Once the cover is off, you'll see the black brush caps. Remove the black caps with a flathead screwdriver and the brushes will slide right out.....

 

[driftpin]

A pencil eraser will usually do a decent job of cleaning a commutator, just make sure to remove any residual rubber. Make sure there aren't any commutator segments linked by carbon dust, contact cleaner spray and an air hose blast probably will take care of that.

 

[toplessHO]

I save old Popsicle sticks for things like this
sharpen on bench grinder to desired thickness.
I will dive into it tomorrow,time permitting

 

[toplessHO]

now I remember whey the end cap never came off.
2 screws frozen in the aluminum,heads stripped that poor excuse of a phillips slot.
so about an hour of working it with PB blaster and finally got them out.
A spin and quick trigger action will get some arcs and sparks and a little rotation
but brushes and communtator will need attention.
My brushes wont come out like the picture shown,theres a metal plate that retains it and dont want to force it and bend it up.The spring and copper lead come out but carbon brush is behind that plate.

 

[toplessHO]

found out why the brushes wouldnt come out.
Corroded to the brass brush holder.
had to chisel them out with ice pick tool and small screwdriver.

Even when broken up the little bits still stuck to the brass.
Should be good when I get new brushes,cleaned the commutator
by spinning the arbor and laying a file flat on it,then used some sandpaper to finish smoothing it out.

 

[Dingleburry]

 

[dnschmidt]

One of the happiest days of my life is when my 14" abrasive cut off saw quit (Ryobi) as that meant I could go out and buy a 14" dry cut saw guilt free. Every time I use my dry cut saw I thank God he killed that spark throwing pig.

 

[sberry]

I actually like an abrasive for repair work.

 

[toplessHO]

nice bench