shop vac overheating? Outlet cap the culprit?

[Jay Yoder]

I purchased a shop vac on closeout from the Blue BORG a few years ago and just got it out of box to use it last week. After about 2-3 hours of non-continuous use, it started to smell burnt. The longest it ran continuously was 10-15 minutes. This particular model came with an outlet "diffuser" that threads over the outlet connection. Do you all leave this on? If I leave it off it will blow dust everywhere! I also had another vac that burned up/quit working after little use and I had left this diffuser on as well. I began wondering if this cuts down on airflow and cooling to the motor? I have a third shop vac (yes I am an addict) that I bought 6 years ago and have used heavy with no issues but I took the cap off and replaced with muffler I got at the BORG. Is this cap an issue for anyone else?

[Myk Rian]

This particular model came with an outlet "diffuser" that threads over the outlet connection. Do you all leave this on? If I leave it off it will blow dust everywhere!
Do you have the filter on correctly? Check that. It might blow drywall dust, but it shouldn't anything else.

[Jay Yoder]

Myk, the filter is on correctly. It doesn't bypass dust, but when I take the cap off the motor exhaust, it is so strong and concentrated it blows paper and dust and whatever else is in its path everywhere.

[Myk Rian]

Sweep the floor.

[Jason Roehl]

What have you sucked up with your shop vac? If you're vacuuming very fine particles, the filter will clog quickly, which will reduce the airflow through the impeller, which will then overspeed and overheat (that's why the pitch of the noise goes up when you block the hose inlet). For any sanding dust, be it drywall, wood or others, you should use a disposable bag in addition to the filter (I get the ones rated for drywall dust).

[John K Jordan]

For any sanding dust, be it drywall, wood or others, you should use a disposable bag in addition to the filter

I agree with the comment that fine particles will clog the filter and reduce the airflow and cause overheating.

I use a bag over the filter which makes a huge difference. I don't use a disposable bag, I simply slip a burlap bag over the paper filter and hold it in place with a removable nylon wire tie. The burlap keeps the paper filter from clogging and I get a much higher suction and much longer times between cleaning the filter. When the vac is full or I notice a reduced suction, I shake the bag out, knock and blow the dust out of the filter with compressed air (outside, of course!) and all is like new with no disposable costs.

JKJ

[glenn bradley]

I've run a Ridgid vac with the diffuser on for 13 years and it is still going strong. The vac will get hot if run for 10 - 15 minutes; hot enough to be unpleasant to lay your hand on the motor area but, not so hot as to burn you. How is your electrical? Could the vac be on an inadequate circuit that makes it heat up more than normal?

[Bill Orbine]

Shop vac from Lowe's doesn't have a good reputation with me. Burned two up and in garbage they go. Rigid from HD seems dependable after 7-8 years of service and it's still running. I use these on field.

[David Malicky]

The diffuser shouldn't be much of a restriction. Like Jason said, if the motor speeds up when the diffuser is on, it is restricting. Else, that's not the problem.
Agreed that ShopVac brand is not as reliable as Ridgid.

[Jim Finn]

I have killed three shop vacuums before giving up on using them with my scroll saw. I ran them longer than 15 minutes because I am often at my scroll saw for hours. I now just blow the dust to one side with a hair dryer mounted to my floor lamp beside my saw.

[Mike Henderson]

The diffuser shouldn't be much of a restriction. Like Jason said, if the motor speeds up when the diffuser is on, it is restricting. Else, that's not the problem.
Agreed that ShopVac brand is not as reliable as Ridgid.
+1 I had one of those Blue Borg vacs. I never had a problem with it overheating but it was LOUD. I got a Ridgid from HD and have been satisfied.

The cooling air for the motor is separate from the vac air. If the motor runs at a higher speed, it should get more cooling air. It *should* be designed not to burn up even if the suction is blocked or the filter is clogged. I would consider it poor design if it did - things happen and the vac shouldn't die because of a restriction.

Mike

[Jay Yoder]

What have you sucked up with your shop vac? If you're vacuuming very fine particles, the filter will clog quickly, which will reduce the airflow through the impeller, which will then overspeed and overheat (that's why the pitch of the noise goes up when you block the hose inlet). For any sanding dust, be it drywall, wood or others, you should use a disposable bag in addition to the filter (I get the ones rated for drywall dust)..

Jason, All I have sucked up is saw dust and some larger chunks of wood. I have the pleated filter it came with installed as well as a drywall dust bag that you mention. Interestingly enough, the noise dropped lower instead of the noise that I have heard when it gets full.

[Jay Yoder]

Just to update situation, I called shop-vac and they have a new power head on the way. In discussions with the tech, I was advised that the cap might slightly restrict flow but that should not have burned up the motor. She also advised to not run it for more than 30 minutes consecutive. Then it needs cool down period. I took apart the burned power head and oiled the bushings but did not feel any drag. When I checked the armature (???) It seems that where the brushes were contacting the rotor, there appeared to be drag marks left on the rotor. It also had a trail of soot looking substance on only one half of the rotor. I wonder if that is the problem? Regardless after running for 5 minutes the smell came back and continued to get progressively worse.

[Tom M King]

Don't know if this is part of the problem, but there is another filter up under the motor housing. There are a few screws to take the cover off the motor. Take that apart, and clean it out.

Nice of them to send another motor.

[Jay Yoder]

Tom, I have never heard of another filter. where is it again?

The replacement motor came today (talk about excellent customer service). It installed quickly and was back up and running in 5 minutes. The vac seems to be smoother and after 5 minutes or so I didn't smell the burning I had before. We shall see how long it lasts, but for now we are back up and running. I looked at the vac and it appears to have 2 intake nostrils on the front (hose side) of the unit. Thanks all for your input, next time I may try Rigid. Merry Christmas early to all! Stay safe!

[Charles Lent]

I have killed three shop vacuums before giving up on using them with my scroll saw. I ran them longer than 15 minutes because I am often at my scroll saw for hours. I now just blow the dust to one side with a hair dryer mounted to my floor lamp beside my saw.

I was given a whole house vacuum system when they rebuilt the house next door. I cleaned it up and installed it my 1 car garage sized shop to use with my scroll saws, sanders, drill presses, and to vacuum the shop floor and my cars and truck. I installed an inlet port on each floor of my small shop and an inlet through the outside wall next to where I park my cars and truck. I added an Oneida Dust Deputy separator in the line ahead of the vacuum. I've been using this system all day most days since it's installation last Spring.
The unit itself with the Dust Deputy and 20 gallon collection barrel are located in my shop's attic.

The Dust Deputy has removed all of the visible sawdust from the air stream and the filter in the central vacuum is still just as clean as it was when I installed the system last Spring. The exhaust from the vacuum unit is piped to the outdoors, so if by chance the super fines are getting past the filters, it is going outside instead of back into my shop. I put large hooks across my shop ceiling in the general direction of each tool area, so I can re-route the 25' hose to where I will be working, yet keep it off the floor. I can now scroll saw with much less saw dust in the air or on me. I haven't yet figured out a good way to collect the saw dust from the top of my scroll saws, but it is collecting 98%+ of the bottom saw dust. Having an inlet outside near the parking area lets me clean my cars and my truck very easily too.

A new whole house central vacuum is quite expensive to buy new, and for most people it would probably not be worth buying one for this purpose, but mine was totally free and cost me slightly less than $150 to install it, which included the cost of the used Oneida Dust Deputy that I bought from a friend who was closing his commercial woodworking shop. It isn't a big enough system to collect sawdust and chips from my Unisaw, jointer, or planer, but it handles the rest of my saw dust problems quite well.

Charley

[Tom M King]

Tom, I have never heard of another filter. where is it again?

The replacement motor came today (talk about excellent customer service). It installed quickly and was back up and running in 5 minutes. The vac seems to be smoother and after 5 minutes or so I didn't smell the burning I had before. We shall see how long it lasts, but for now we are back up and running. I looked at the vac and it appears to have 2 intake nostrils on the front (hose side) of the unit. Thanks all for your input, next time I may try Rigid. Merry Christmas early to all! Stay safe!
When you take the plastic housing off the motor, there is another filter around the motor that filters the cooling air. I don't remember details about a ShopVac, but do remember taking one apart once. I had to clean one of my Rigids just a couple of days ago. If that filter is clogged up, like from the filter falling off or many hours of use, not only will the motor overheat, but the suction of the whole vacuum is greatly reduced.

[Jay Yoder]

sorry to resurrect an old post, but...here goes. After using the "new" motor for about a total run time of 2 hours (in maybe 5-10 min intervals) the second motor went out! I had it on for about 3 minutes just sweeping up the floor and the pitch started to change. I looked over and there was smoke coming from the powerhead. I called ShopVac and they were surprised to hear and shipped another motor out. I asked if this was a unique motor to my model and was told it was on a lot of different units. They sent another motor this time but weird thing is it appears to have been used or not protected in storage as there was a bunch of cardboard dust on it. I am so frustrated. I wonder if when they build for lowe's they reduce the QA to meet a price point? I have an old (11 years+) Shop Vac with same rating and it has had no issues with drywall dust to water. Maybe this particular one is cursed. Any thoughts on this?

[Steve Peterson]

After 2 failed motors in such a short time, I would not bother trying a third one. I would try to return it and go with a Ridgid. It sounds like the blue one is a bad design and not worth the hassle.

Steve

[Jay Yoder]

normally I would agree with you Steve, but since Shop Vac is trying to get this right (and sent me new motors) I am trying to work with it...I tested the motor tonight and it appears that the carbon brushes are chipping off. When I started it, it sparked heavy and sent some small chips flying. I am not an electric motor guru, but am wondering if the brushes are too close to the rotor and catching on the gaps?

[Ken Fitzgerald]

Jay, the brushes actually are supposed to make contact with the rotor. It's not unusual to see particles breaking off until the surface of the brushes are worn to match the surface of the rotor.

The springs usually attached to the brushes set the force applied to seat the brushes to the rotor surface. I wouldn't be concerned about that.

[Jay Yoder]

Ken, I have been watching youtube vids since I posted and now have better understanding of how they are supposed to work. What I find odd is that they seem to have not been ground off (like disc brakes on a car) but numerous flakes/chunks. There also appears to be a groove around the bottom of the commutor (???) where the brushes contact the rotor. Wonder if the tray the brushes sit in contact the rotor?

[Ken Fitzgerald]

I don't think the brush tray should make contact with the rotor surface. Some of the ones I have worked on the tray was conductive and made of brass. The end of the brush had a brass "piece" for lack of a better term which fit into the "tray" and also made contact with a brass surface in the brush cap. The wiring actually made contact with the tray, if you will.

Typically, most of the brushes I have replaced were rectangular and of course, the surface of the rotor is curved so it takes a while for the brushes to wear to the shape of the rotor surface.

Let it run for a while and then check them. It never hurts to remove the brushes and then vacuum the brush holder and manually rotate the rotor. In fact, part of planned maintenance on some of the CT scanners I maintained, had us do just that. Brush dust is conductive and when it builds up between the individual contacts of the respective rotor surface can short and cause problems.
I would not blow them out with compressed air as you can't control where the dust goes.

For now, I wouldn't be too concerned.