Vac Motor Spitting Fire

[sleddriver]

I have a small, old Sears shop vac that's served me well for many years. Recently, I smelled something hot and noticed some smoke so I immediately turned it off.

Today I disassembled it and found the motor shaft tight in the upper bushing. I re-oiled the bushing packing with M1 10W-30 via a syringe and cleaned the lower shielded bearing and repacked it with grease. So good so far.

Using a brass brush I cleaned off the commutator, exposing bright shiny copper. The brush springs are fine with lots of length left on the brushes. However, I noticed there is a bit of side-to-side play in their holders.

I reassembled, checked to make sure the shaft freely turned and lit her off.....literally.

Lots of fire, sparks, a bit of smoke and the motor quickly heated up. It was on maybe 5 sec.

Pulled it apart, removed both brushes and sanded the face flat again to a smooth finish. Re-brushed the communtator. Both haves of the armature measures 1.1 Ohms, so it's not shorted.

Put her all back together, checked to make sure all wires were clear. I noticed that when I spun the shaft by hand I could hear rapid clicks coming from the brushes running across the commutator. Even though I'd just sanded them. I wonder now if the commutator is warped?

Lit her off again...still too many sparks, but better. I can see arc flashes, a quick flame or two. Somethings still wrong.

Any universal motor guys out there understand what's going on? My shop vac has turned into old sparky...

 

[Donald]

Time for a new one.

 

[GreeCguy]

Is there any play in your bearings in any direction? Sometimes, bearing will wear on one spot, (like on a dryer motor) and will spin freely until the juice is put to them. If it were me, I would take the motor apart again and check for bearing play in all directions. It only had to be a little off to cause havoc.

 

[SF0059]

I worked in vacuum repair for 10 years. If you check the armature right below where the brushes ride, do you notice any significant discoloration? Typically purple or blue. If you see that then the armature is shot. Typically better to get a new vac at that point.

 

[sleddriver]

Originally Posted By: GreeCguy
Is there any play in your bearings in any direction? Sometimes, bearing will wear on one spot, (like on a dryer motor) and will spin freely until the juice is put to them. If it were me, I would take the motor apart again and check for bearing play in all directions. It only had to be a little off to cause havoc.


No, it's not the bearings. The shaft spins freely.

 

[sleddriver]

Originally Posted By: SF0059
I worked in vacuum repair for 10 years. If you check the armature right below where the brushes ride, do you notice any significant discoloration? Typically purple or blue. If you see that then the armature is shot. Typically better to get a new vac at that point.


Definitely deep blue, like steel that's been overheated. It's easily taken back to shiny copper with a brass brush though.

Closer investigation of the commutator revealed that each bar had a ridge along one long edge. I took a fine file and removed them all, then polished the copper with syn steel wool.

Put it all back together, sparking now almost zero! Unfortunately, something else is going on as the rpms are too low, there's no torque, the motor metal quickly heats up, and I can smell heat.

Plugged it into the Kill-A-Watt....the motors drawing 18A, wattage is over 1600 and the shop lights dim a bit. So I quickly turned it off. This has all the signs of a short.

Shorted armature caused by over-heating last time it was used?

 

[Donald]

The vacuum is looking to head to vacuum heaven and you should head to HD and get a Rigid (or a cordless Dewalt, my new favorite vacuum).

 

[stephen9666]

I really commend you for doing as much as you have done to try to save it. I'm big on trying to fix my tools, but even I would have given up well before you did. I think you've done enough and it's time to cash in your tokens on this one and get a new model

There are lots of threads on choosing a wet/dry vac on Garage Journal. Here's one recent one to get you started:
http://www.garagejournal.com/forum/showthread.php?p=3085874


To add to an above comment, many people like the Craftsman and Ridgid models. They're both made by Emerson and they're mostly made in Mexico.

I recently decided to go fancy and bought a Stihl branded vac that is a rebadged Nilfisk-Alto. It's made in Hungary and I've been pretty pleased with it.

 

[sleddriver]

Originally Posted By: stephen9666
I really commend you for doing as much as you have done to try to save it. I'm big on trying to fix my tools, but even I would have given up well before you did. I think you've done enough and it's time to cash in your tokens on this one and get a new model

There are lots of threads on choosing a wet/dry vac on Garage Journal. Here's one recent one to get you started:
http://www.garagejournal.com/forum/showthread.php?p=3085874


To add to an above comment, many people like the Craftsman and Ridgid models. They're both made by Emerson and they're mostly made in Mexico.

I recently decided to go fancy and bought a Stihl branded vac that is a rebadged Nilfisk-Alto. It's made in Hungary and I've been pretty pleased with it.

Thank you! Thank you indeed...I've recently brought an old Vornado fan with dried bushings back to running condition...it wouldn't even start without flipping the blades, so I thought this one was worth a closer look.

I do always attempt to fix my tools before junking them. I've learned a lot that way. I'm getting old enough to be 'old-fashioned'.

Somethings definitely FUBAR with the armature. I gave it a close look, measured across a few commutator bars for a low of 0.5 Ohm to 1.7. But I'm not sure how these things are wired.

Fortunately, I have a small Fein for a back-up. Excellent little vac. Very quiet. It sees no 'nasty' duty, only indoors, car, wood shavings and that's about it. No neighbor is ever allowed to use it either!

Thanks for the link to start shopping.

 

[stephen9666]

Originally Posted By: sleddriver

Fortunately, I have a small Fein for a back-up. Excellent little vac. Very quiet. It sees no 'nasty' duty, only indoors, car, wood shavings and that's about it. No neighbor is ever allowed to use it either!


Ah, good choice on the Fein.

That was another vac on my list when I bought the Stihl. I wanted a Euro vac, and the rebranded Nilfisks sold under the Stihl brand were by far the most affordable way to get a Euro vac.

They seem to be a step above the normal wet/dry vscs sold in the US. But as you noted, spending good money on the vac makes me hesitant to really use it hard. If it was a cheap Ridgid from Home Depot I'd have no problem trashing it in a few years or using it hard. I can actually see the appeal of getting one that works well and you aren't afraid of ruining it.

 

[sleddriver]

Originally Posted By: stephen9666
Originally Posted By: sleddriver

Fortunately, I have a small Fein for a back-up. Excellent little vac. Very quiet. It sees no 'nasty' duty, only indoors, car, wood shavings and that's about it. No neighbor is ever allowed to use it either!


Ah, good choice on the Fein.

That was another vac on my list when I bought the Stihl. I wanted a Euro vac, and the rebranded Nilfisks sold under the Stihl brand were by far the most affordable way to get a Euro vac.

They seem to be a step above the normal wet/dry vscs sold in the US. But as you noted, spending good money on the vac makes me hesitant to really use it hard. If it was a cheap Ridgid from Home Depot I'd have no problem trashing it in a few years or using it hard. I can actually see the appeal of getting one that works well and you aren't afraid of ruining it.

I bought it (Fein) used for a song...couldn't pass it up. Took it all apart, cleaned it up; very impressed with the way it's put together.

It and the old Craftsman made a great team. The later wasn't too loud, accepted the Fein hose, as well as 2-1/2" larger hose for use with the bandsaw, drill press, etc. I used it to suck up water on rare occasions. It performed well...had it about 30 years.

 

[sleddriver]

Originally Posted By: stephen9666

.....many people like the Craftsman and Ridgid models. They're both made by Emerson and they're mostly made in Mexico.

Made a trip to Lowes to check out their Shop-Vacs...not too impressed. HD next...they have one that's about $100 labeled 'their quietest vac sold'. Wasn't able to turn it on and can't tell what would make it so quiet as all the air expels out of a blower port. They even sell a 'muffler' for the blower port for an additional $11!

A bit bigger than I need..it's 12 or 14 ga. but their 8ga or maybe 9ga is much louder though I was unable to find any reliable data on the box nor from the employee.

Also found a bag filter at HD that fits the Fein. Been cleaning up lots of wood shavings lately.