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Well, crap.

Something is wrong with my edge sander. I turn the switch and I can hear electrical hum going to the motor, but it doesn't turn. It worked fine one minute, didn't work the next. Gave no symptoms or sign, just stopped moving the belt.

Any ideas? It's a staple tool in my shop...

Blown starting capacitor on the motor?

Seized bearing somewhere?

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

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Pull the guard off the fan and see if you can turn the drive....careful with plastic fans. That's a good place to start.

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Motor brushes???? Take it apart. What have you got to lose.

I would try taking off the belt and seeing if the motor will spin up without being under load. If it doe it is likely something to do with the capacitor or centrifugal switch that is usually on the far end of the motor shaft. If it won’t spin up, even with a careful nudge, it could be something else. This is assuming it is a single phase induction AC motor.

Kent

Usually when a bearing goes bad it gives some prior indication (grinding sounds). I have seen a centrifugal switch get so packed with saw dust that it wouldn't operate properly, but that was in a table saw.
Induction motors don't have brushes.
A couple of videos on checking caps and the switch:
https://www.youtube.com/watch?v=4RRB7tvm-eU
https://www.youtube.com/watch?v=hsZ_k_YkUEE

First thing to do is make sure you have full power to the receptacle from the breaker panel. Next, that the switch on the machine is functioning correctly. If it is a 220/240 motor losing one of the 2 hot legs could be a cause. Check motor wiring connections. Some motors have a built in thermal overload breaker that can be reset after the motor cools down, often a small button on the motor housing.

Then as stated by others, motor starter capacitor and switch, seized bearing...

Good luck

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Brian R, Wood Mechanic
N8ZED

Thanks folks, I'll poke about a bit...

Well, without belt and with a little encouragement it spins without load. Sure sounds like what the guy in the vid thought was a start capacitor, although his trouble was an inertia switch...

I guess Tapatalk won’t let me upload a vid...


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Make sure power/receptacle is good.
Humming likely means the switch is ok.
Sometimes (like a bandsaw) you can rotate by hand, start, and sometimes it will go. SAFETY!
The start winding switch in a lot of woodworking equipment gets dirty or fail.
I had mine repaired a couple years ago as it wouldnt start and just hummed.
Even the sealed motors seem to get dirty.

not a professional, just handing off my experience.

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Wake up and smell the rosewood!

I replaced the starting capacitor on mine when it did that. It's been working great ever since.

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Hutch

Get the heck off the couch and go build a guitar!!!!

The start capacitor is relatively easy and cheap to replace. The centrifugal switch is a bit more of a hassle, but some of them aren't too bad, and it could be that it just needs to be cleaned up. Sometimes you get lucky and the fan and switch is located behind a cover on the back end of the motor. And sometimes you don't. There are several different types so locating a replacement for the one you have can be a hassle. That type (brand)of edge sander is it?

If you hear a "click" when you turn off the motor and it winds down, that is generally the switch returning to the non running position


https://www.youtube.com/watch?v=J_FziYNp4Qs

It's a Canwood Big Boy 80...

From the pictures of the unit the motor looks like it has a fan (and probably the centrifugal switch ) located under the cover at the back (bottom) of the motor. You could remove the cover and try blowing out the switch first, before trying other methods of cleaning.

Check the brushes


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is this the type of thing an electrician would know how to fix, or is this more of a tool repair gig? I ask because I know an electrician...

Indeed there is a fan on the bottom, which I assume would blow cool air as well as dust on the motor...

And here looks like a hub for a capacitor if that is indeed the probkem
It does indeed make a very distinct audible click as it’s winding down, so maybe it is something as simple as the centrifugal switch.

I’ll have to pull it apart and see. Not the most convenient layout for that, ah well.

In the vid about capacitors, he was careful to sap off any stored voltage first. If I’m just messing with the fan and switch do I need to worry about that?


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Assuming the switch is located behind the fan, it would be easy enough to remove the (3?) screws that hold on that cover and blow out the dust from that area. You may also be able to clean the contacts without disassembling anything. The switch should make a click when it winds down - that is the contacts closing as the centrifugal forces are no longer strong enough to keep them apart (which then puts the start capacitor back in the circuit). But dust on the switch or contacts could be keeping the circuit from closing completely (which would keep the start cap from getting a charge to start the motor).
If you are going to fool with the caps it is best to short across the contacts to discharge them as shown in that video, just for safety"s sake to avoid a bad shock.
I do see a fair amount of saw dust around the fan cover, so there may be a surprising amount inside it. Blowing it out is the first thing I'd try.

Mr. Bond's edge sander appears to be equipped with an induction-type electric motor. At the risk of sounding like a modern sex education video for primary-schoolers, (most) universal motors have brushes and induction motors do not. And to make that statement even more an echo of some of the recent and sillier cultural rumblings, not all universal motors actually have brushes - some universal motors use electronically-controlled switching of the electromagnetic coils in the motor versus the more common commutator and graphite brush architecture.

The linked article by Mr. Schwarz - a woodworking author held in the highest regard by himself and others in that community - explains the salient differences between universal and induction motors.

https://www.popularwoodworking.com/techniques/what_you_must_know_about_motors1/

The second linked article covers the differences between brushed and brushless universal motors, with the brushless variety rapidly replacing brushed universal motors in battery-powered tools, but likely to fully replace brushed motors in corded portable and bench-top tools as well over time.

https://www.protoolreviews.com/news/brushed-vs-brushless-motors/18990/

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This seems helpful...

https://youtu.be/M-j6PhthXJY

Thanks for that video Ed, it is a good one.

When my motor failed, my compiled research took me through all those steps....would have been nice to watch just one vid. : )

I did not have any success and ended up bringing my motor to my local shop.
He replaced the switch - cost me $100 total to have repaired. Switch & shop time.

He recommended to me not buying a new motor and that the "farm duty" Leeson 1.5hp was worth the $100 dollar repair.

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Wake up and smell the rosewood!

Very hoping to not replace motor...

Hi Ed,
The edge sander I have is a Grizzly 6X80. I got it with another tool, which is what I was spending the money for, so I didn't feel I had any money in it. I knew it was on it's last legs when I got it, and I don't use one that much, so when it died I wasn't too concerned about it. When I looked at the way the motor was made I noticed the shaft had a tapered end the drum mounted to, so I couldn't just put a standard motor on it. Not wanting to buy another crappy Grizzly motor I decided to bodge another motor to the shaft by removing the fan and switch and adding a rubber hose and a couple of hose clamps and mounting a motor I had in line. It's not real elegant but so far it's working.

Eek! Fingers crossed that I can gently fondle the centrifugal switch into being nice again...

Have you checked the capacitor yet? That is the easiest to check since it is right on the outside and they will often leak or bulge when bad, so if you see either of those things you know what to do.