Removing Stuck Brushes in a Delta Motor

[Doug Hobkirk]

I bought a Delta Sawbuck for $40. Very good condition. We plugged in the motor and it sounded OK. After getting it home, the motor would sometimes not turn on with the switch. Bad switch? Wiring? Motor problems? Brushes?



So I dismantled things enough I could clip my VOM leads on the ends of the soldered wires running to the brushes. (The front bearing and gear reduction unit have been removed.)
Then I activated the switch several times - the motor response was intermittent, and would not run more than a few seconds. Sparks. The VOM confirmed voltage.
Question 1 - Does this indicate probable bad brushes?


So I figure it is probably the brushes, although there's nothing that looks beat or worn-out or abused. Even the 8" Delta blade (it looks original) looks decent. The seller said he used it for one job. This is what a new brush looks like (http://www.ereplacementparts.com/brush-and-spring-p-68142.html?osCsid=8uk63t9o1hg1vml97v0i10fgt0). This is what they looked like for a CWMoser in another forum:
288272
And this looks like what I am chasing.



I removed the brush covers but I could not get the brushes out - I did not pull really hard.
I can see the tip of my most tiny long needle-nose pliers reaching the armature.

I avoided having the copper "cap" of the brush assembly obstructing my pliers.
Twisting and pulling the pliers doesn't seem to do anything.
After studying the above picture, I went out and tried some more "normal" needle-nose pliers (I probably have 20-30 different ones). But none could pull the block out.
Question 2 - Should I hit the area under the coiled wire with a penetrating oil like PB Blaster?


I have tried getting a screwdriver on the armature end of the brush to no avail. I don't know how fragile the "commutator bar" is, so I did not get aggressive.
Maybe if I remove the armature assembly (I don't really know if this is possible) I could push the bushings out.

I removed the screws from what I assume is a rear bearing - I can rotate it independent of the armature shaft but I was not able to pull it off. Again, I did not get aggressive.
Question 3 - Is it OK to get aggressive?
But maybe this last strategy is a fool's errand. I did try to remove the two Phillip head screws the seem to hold down a plate at the other end of the armature and they did not want to budge. I am pretty sure I felt one start to go soft. I can deal with stripped screw heads if necessary, but naturally I would prefer to avoid the significant hassle.



I have reached my level of incompetence. Can you help me?

DELTA SAWBUCK NOTE - The Sawbuck impresses me. It cuts up to 14" wide and 2.5" thick stock. The angle adjustment scales are huge - maybe 1/4" per degree! Clever engineering, adjustments possible for just about every piece, etc. The fences are adjustable, the miter range is 47 degrees R or L. The whole saw slide assembly is very solid with an excellent pivot point. And it tilts (only to the right) up to 45 degrees. The blade is 8".
I bought it ($40) to give a contractor that I owe a favor - he recently noted he didn't have a table saw and wished he did (he's really into working metal, not wood - a good table saw would be a poor use of his shop space).
I believe someone in this forum said it would be excellent for a siding or trim contractor. The only problem might be that the wood (or plastic) must be fed in from the side, something I hadn't thought of.
288271

[Bill Neely]

Doug, The stuck brushes are causing the problem, the springs aren't able to push them down onto the commutator and after they wear away slightly they only get contact intermittently.

On my old Hitachi miter saw I removed stuck brushes with a chisel shaped dental tool, you could probably use a very thin bladed screwdriver too. (prying them up off the commutator) Once you get them moved a little they may pull right out.

After I got mine out I cleaned out the brush holders with solvent and a small bottle brush then cleaned the sides of the brushes with a little fine garnet sandpaper.

I wouldn't use any penetrating oil, probably wouldn't get aggressive in any way until I'd exhausted all other possibilities.

[Kyle Iwamoto]

WD-40? That worked for the stuck brushes on my Ryobi cheapo table saw. Granted, I spent 65 dollars on my POJ Ryobi, much more than you spent on your sawbuck. Nice score! That was the initial use for WD-40. Cleaning electrical stuff. Everyone knows its not good as a lubricant. It can't hurt it. Oh yeah. A few love taps also helped the brushes.

[Duane Meadows]

WD-40? That was the initial use for WD-40. Cleaning electrical stuff. Everyone knows its not good as a lubricant. It can't hurt it. Oh yeah. A few love taps also helped the brushes.


May have been the initial use, but it's not good for the purpose. If you do use it for that, be sure to get it washed out as completely as possible! After it sets, it will leave a greasy, waxy residue that will make a mess, collect dust, and generally isn't good for electronics. I have followed too many TV techs that thought it was good for contact cleaner. The results are not good.:( It will work short term, but if you have to clean it up with contact cleaner, why not just use the contact cleaner to begin with?

[Doug Hobkirk]

Doug, The stuck brushes are causing the problem, the springs aren't able to push them down onto the commutator and after they wear away slightly they only get contact intermittently.

On my old Hitachi miter saw I removed stuck brushes with a chisel shaped dental tool, you could probably use a very thin bladed screwdriver too. (prying them up off the commutator) Once you get them moved a little they may pull right out.

After I got mine out I cleaned out the brush holders with solvent and a small bottle brush then cleaned the sides of the brushes with a little fine garnet sandpaper.

I wouldn't use any penetrating oil, probably wouldn't get aggressive in any way until I'd exhausted all other possibilities.

Thank you. You reassured me and I attacked anew.

WD-40 (see next post after yours)
Tapped down on both sides of brush with flat blade screwdriver (attempting to break sticktion)
I used pretty delicate bent needle-nose pliers
I stuck them in as deeply as could using gentle hammer taps
Pulled but the pliers kept slipping off (they had been doing that before the WD-40, but I am sure that didn't help) - many tries
Repeated gripping with pliers but now I flipped the motor over so plier tips were pointing up (i.e., the brush would go downward to come out)
Held the brush as tightly as I could with one hand while I tapped on the flat of the pliers (where they pivot) with the end of a claw hammer - VIBRATION, IMPACT, whatever
It took several tries on both sides but both did come out. Hooray!


The brushes look decent, except for some divots on the top edge from the pliers. If closer inspection shows they are damaged, replacements are available. I will try some sandpaper as you suggest and see if I can get them to slide up/down somewhat freely. I don't want my friend to have to do this again.

Thank you, thank you

[Doug Hobkirk]

May have been the initial use, but it's not good for the purpose. If you do use it for that, be sure to get it washed out as completely as possible! After it sets, it will leave a greasy, waxy residue that will make a mess, collect dust, and generally isn't good for electronics. I have followed too many TV techs that thought it was good for contact cleaner. The results are not good.:( It will work short term, but if you have to clean it up with contact cleaner, why not just use the contact cleaner to begin with?

Oops? I didn't read your post until after I had used the WD-40. Contact cleaner sounds like a good way to remove the oily feel. Thanks for the idea.