How do you lube your.... Squirrel cage blower?

[cnice_37]

This is our 6th year heating with our Jotul insert. Tonight I took apart the blowers for the first time for a good cleaning. See a little before and during action.

So is there anywhere to lube these things? It seems that exposed lubricant would attract more dust, but it would also seem I should lube up something while I'm in there.

What do you guys do? Like a little lube, or au naturale? Oh, and what kind and where? And take it easy on the "where" replies!

 

[Whitespider]

Some blower motors (well, not just blower motors) have ports, or tubes that lead to the bearings. Normally they have some sort or plastic or metal cap on them... you're supposed to put a couple drops of light motor oil in them every-so-many-hours. Other motors have whats termed "permanently lubed" bearings... they're sealed and there ain't any way to lube them. Your motor appears to be the sealed type... put the blower back together.

 

[cnice_37]

Another question, is there any way to snug up loosened rivets besides new rivets?

 

[513yj]

I've tried a lot of things with no real lasting success so if there's an answer I wanna know too. What I usually do for this situation is drill out the old rivet and get finer thread self tapping screws or if it's possible machine screws and nuts. One thing to try since it does appear you have sealed bearings is to put graphite or teflon powder on the squirrel cage shafts before you put it back together it may help some.

 

[Festus]

What Whitespider said, but also, while you have it apart, you should check the bearings. I couldn't tell from your pictures what kind of bearings you have. If they are sealed bearings, turn the inner race of the bearing with your finger. If you feel ANY, and I mean ANY roughness or loose movement other than a smooth, tight spin, the bearing will not last much longer. If it hasn't already started making noise they probably will soon, lubed or not. If there are exposed rollers of some kind, or they are just a simple bushing, you could dab a little light white grease in there.

All that being said, although I see failed bearings in vehicle HVAC systems all the time, I have not on a furnace blower (but I work on vehicles, not home systems). I could be wrong, but I think the bearings and/or brushes on the motor end would probably fail before the squirrel cage end. Whichever fails first, I would probably replace the whole unit. Mainly because if any bearings fail, the brushes and armature wouldn't be far behind. That would likely be your only cost effective option. I like to fix things just once.

Also, I would take compressed air, and blow the motor end out since you have it apart.

Take my advice for what it's worth. I have no specific experience with the unit in your pics, just a whole lot of experience fixing a whole lotta different stuff. Good luck.

 

[Festus]

Another question, is there any way to snug up loosened rivets besides new rivets?

No, not really. Anything you try is likely to bend something around it or mess it up. Either drill it out and replace them, or add a similar sized sheet metal screw, or machine screw next to it if space allows.

PS...The advice on my previous post about brushes and armature may not be valid if the motor is brushless.

 

[LegDeLimber]

Shaded pole motor. No brushes, not much starting torque but quiet running.
Shaded-pole motor - Wikipedia, the free encyclopedia
often used in locations where you need a quiet running motor
with low vibration.
lacking a start winding & switch and or capacitor or brushes generally makes for a long service life.

*Typically* have spherical, lube impregnated bronze bushings.
Watch your alignment when reassembling/ snugging up the through bolts,
as the diecast end frames may have a bit of clearance in them
and with the spherical bearings
it's easy to get the motor assembled in a twist.***

also self tapping screws may have pulled up the metal (a burr)
at the begining of the holes and can cause the frames to sit in a twist
or work loose later
when the burr flattens after running a while. (watch for loose shaving from threads also)
Then you get to take it all out again and maybe have a bent fan wheel too.

***That can cause re-fitment problems in the duct work and/or rubbing parts later when a little dust gets built up and the resulting wobble uses the smaller
that normal gap
created by the crooked motor assembly.

Dust really drys out the lube in those pressed metal/pre-lubed bearings
and you may begin to get the rumble or squeaking.
By that point the shaft is usually a bit worn also and cleaning & relubing
tends to be a stopgap measure to buy some time to find a replacement.

Can't tell from the viewing angle, but the end frames look large enough
to possibly have ball bearings.
If so, all the usual maintenance answers for that type apply.
Are they sealed (probably, considering the application) or open?
will dictate your options of course.

Loose pop rivets?
Personally, I like the idea of replacing with fine thread screws and nuts.
Be sure to use some thread locking compound on them.
You don't want them working loose, once installed in the middle of your equipment.
(was likely a factor in the manufacturer's choice of rivets)

In a pinch, You can pinch.
Take a pair of locking pliers and just barely set the screw to clamp
and squeeze/crush the rivet a bit. Repeat a few times while tightening
the plier screw just enough to cause a bit more pinching pressure.
But it's only a temp answer really.

Yeah You can see why I vote for replacing with fine pitch screws and nuts
or drill out and re rivet.

 

[Whitespider]

Ya' can't "fix" a loose rivet...

There are two different materials used for common pop or blind rivets, aluminum and steel. Although both can get loose in a vibration environment, specially if done improperly, aluminum tends to loosen much sooner. To have any expectation of the rivet remaining tight, the fit of rivet-to-hole must be as snug as possible (on both pieces of metal) and any burs raised during the drilling should be removed. You need clean, round holes, rivets that fit the holes rather precisely, and smooth, flat metal surfaces. Once the rivet joint becomes loose and the metals start moving it causes the holes to "slop-out" (shear failure)... which means replacing them with the next larger diameter rivet (if done correctly, actually makes a stronger joint than the original). Normally, steel rivets should be used for joining steel, especially in a vibration environment. When the metal being joined is very thin, or extra binding strength is desired, a backing washer can be added to the shank side before "pulling the rivet in", increasing the area "pinched" between the head and shank... which increases both shear and tensile strength of the joint. Also, talking shear strength, two rivets relatively close together will provide more shear strength than three rivets spaced far apart... but tensile strength of the joint may suffer if there is any flexing.

 

[cnice_37]

Thanks guys, you have all been very helpful.

I will try an open air run to detect any squeals but turning by hand the bearings feel good.

Will check around for a hand rivet gun, after that it will be bolt and nut with star washer and loctite.

 

[flyinlow]

Mobil 1 cure

The bearings in the motor are bronze and are easily oiled with a hypodermic needle. Buy a hypo. at the local pharmacy-- put a little Mobil 1 oil in the hypo. and slide the needle under the plastic washer next to the shaft. Oil it slowly-- it only takes about 1 cc for each bearing. The felt wick that's around the bearing will hold the extra oil and the Mobil 1 will liquefy the old residue and lube it like new. I have oiled hundreds of these motors with a 99% success ratio. Don't use motor oil on these motors because the additives in the oil turn sticky with age and you will have another problem.

 

[olyman]

The bearings in the motor are bronze and are easily oiled with a hypodermic needle. Buy a hypo. at the local pharmacy-- put a little Mobil 1 oil in the hypo. and slide the needle under the plastic washer next to the shaft. Oil it slowly-- it only takes about 1 cc for each bearing. The felt wick that's around the bearing will hold the extra oil and the Mobil 1 will liquefy the old residue and lube it like new. I have oiled hundreds of these motors with a 99% success ratio. Don't use motor oil on these motors because the additives in the oil turn sticky with age and you will have another problem.

yah beat me to it....agreed...so long as his bushings aren't hogged out yet.......................