Fan Lubrication

[Fratink]

Possibly not the best location but I'm not sure where to ask.

I have a regular floor fan (Seabreeze turbo) that I've been repairing for a while. About every 6 months I'm having to re-lubricate the bronze bearings, which seems excessive to me. I've tried to use a marine grease and 3in1 but both seize up quickly.  What oil do you all use for simple bearing motors like this?

[wilfred]

Have you given the bushing/bearing a good clean out first? I have found that helps but not fully as I'd like. I just use a light machine oil, like for sewing machines. I think the bearing might be impregnated with oil at manufacture and hence oiling the shaft just doesn't seem to work for very long.
I know such bearings exist but not sure if cheap fans use them.

Does the fan start slowly? Do the blades stop spinning very quickly in a few revolutions or does it take 5-10 seconds? Of it stops quickly it needs lubrication/cleaning and if it starts slowly or only on high it is probably the motor start capacitor failing. It can be both and if you torment the fan like this for a long time it may burn out a coil winding.

[helius]

Sewing machine oil, 3-in-1 Oil, or Silent Run are all good choices for electric fan bearings. Grease would be for heavier equipment exposed to higher loading such as a lawnmower.
It's also a good point that the sintered bronze bushing ("Oilite" bearing) was impregnated with oil at the factory and may have turned to varnish or solidified. Brake cleaner can be a good way to flush it out. Re-impregnating the bushing with oil may require heating; be careful not to overheat any plastic moldings or staked mounts.
When designed for long life, these fan shafts sometimes butt against a piece of felt that works as an oil reservoir.

[Berni]

If the reason for lubrication is that the bearing gets too much friction then you might have to clean out the gunk that has collected in it. Flush it with plenty of solvent or WD40 or something. Dry it up as much as possible then apply some machine oil.

If the reason is that the bearing becomes noisy, then it is possible it is getting worn out. If the hole gets worn out too big then the shaft starts to run around in circles around the hole, making lots of vibration and noise. More lube helps mask the problem because the lubricant takes up some of the space and gives the shaft a harder time to grip onto the hole. Don't think there is any easy fix for that.

[Veketti]

I've tried many different oils. Motor oils, gun CLP's etc. Regular synthetic motor oil seem to work the longest, but still the differences are negligible. They all turn to varnish and slow down the fan eventually. My use case is in the wintertime, table fan on top of 3m2 masonry heater to spread the heat. It spins 24/7 max. about month and needs cleaning and relubricating. Best would be to convert it using sealed ball bearings, but haven't had motivation to do that.

[DavidKo]

Bronze bearings need to be lubed continuously. Around steam engines you can see people which are oiling moving parts to keep them moving ;-).

The best is to change to sealed ball bearing in such a case as a fan.

[coromonadalix]

i use tufoil,  but it is a sign it will eventually fail, it will give some time to find substitute ...

[Fratink]

I tried sewing machine oil this time, we'll see if that works.  Thanks for the suggestion!

The bearing seem to be in great shape, they're not sloppy on the shaft, they slide on nicely and feel good. I gave them a good clean with some scotch brite just to try and get built up gunk off the shaft and bearing surface. I think you're right that they are those oil impregnated bearings, perhaps the oil has just gone bad or something?  The motors have tripped their thermal fuses, which I replaced, so perhaps they're running too hot.

[BrokenYugo]

It's overkill but I usually use auto trans fluid (cheap Dex/Merc type) or engine oil, full synthetic preferred, soak the felts around the bearing. Grease may clog up the bearings, they're meant to be porous to wick oil at a controlled rate, if I do use grease there it's just a dab on the thrust face, as the factory does.

I never got this medieval on a fan but dropping the whole bearing assembly in a pot of warmed (needn't be untouchably hot) oil seems to clean them out.

[Fratink]

Sewing machine oil, 3-in-1 Oil, or Silent Run are all good choices for electric fan bearings. Grease would be for heavier equipment exposed to higher loading such as a lawnmower.
It's also a good point that the sintered bronze bushing ("Oilite" bearing) was impregnated with oil at the factory and may have turned to varnish or solidified. Brake cleaner can be a good way to flush it out. Re-impregnating the bushing with oil may require heating; be careful not to overheat any plastic moldings or staked mounts.
When designed for long life, these fan shafts sometimes butt against a piece of felt that works as an oil reservoir.

Helius, I have washed them in brake cleaner so maybe that's why they don't last as long, I washed all the oil out. It didn't occur to me that I could do that.  I might have to rig something up to put oil back in, or find new bushings.

Now that you mention it though, there are felt pads around the bushing. I tried putting oil in them but later thought perhaps I misunderstood their purpose.  These felt pads sit around the bushing, but don't rub up against any mating surface. I thought they might be for cushioning and alignment.  The bushing look like this:

https://www.spboilles.com/Uploads/1469749769565a88a5d7bc7.jpg

The felt pads run on the outside of the sphere. There isn't a pad pushing up against the shaft at all, so far as I can tell.

My hope was that these were designed for long life, as it was assembled in Canada.... but perhaps they cut some corners.

[Fratink]

I've tried many different oils. Motor oils, gun CLP's etc. Regular synthetic motor oil seem to work the longest, but still the differences are negligible. They all turn to varnish and slow down the fan eventually. My use case is in the wintertime, table fan on top of 3m2 masonry heater to spread the heat. It spins 24/7 max. about month and needs cleaning and relubricating. Best would be to convert it using sealed ball bearings, but haven't had motivation to do that.

I've been debating the same thing. I think there's space to put in ball bearings but the actual energy to do that has been lacking.  That said... it might take less time than breaking these down every couple months.

[Fratink]

So, I found a manual for these types of bearing that I thought I'd share with ya'll:

https://www.ntnglobal.com/en/products/catalog/pdf/9015E.pdf

Table 4.4 lists the oil grades for specific loads.  Here's a conversion table to help understand what that means if you're like me and life in the world of SAE:

https://oilviscositychart.com/calculate/convert.php

Light loads use ISO VG 10-22 ish, which is similar to sewing machine oil, according to a https://www.mobil.com/en-cn/industrial/pds/ap-xx-mobil-velocite-sm-series.  For heavy loads you can be getting into ISO VG 100, which is close-ish to 90W gear oil.

To reimprgnate a bearing/bushing you should heat oil to 60C and place the bushing in it for a couple hours, or until the bubbles stop being released. Then let it cool before removing the bearing.

So probably what I'm doing wrong (as a couple of you pointed out) according to this is:

• I'm washing the oil out with brake cleaner
• I'm only putting a little oil back in

For those wondering, I tried lithium grease and that didn't work very well at all.

[David Hess]

For oiling worn bushings, I have had the best results with heavier oils like gear oil or motor oil.  Synthetic gear oil might be better but I have not tried it yet.

[BILLPOD]

Marvel Mystery Oil

[james_s]

These are typically sintered bronze bushings which are a bit like a metal sponge. Typically they will either be impregnated with oil from the factory or there will be a felt ring around them that is soaked with oil. A light machine oil such as one specifically sold as electric motor oil, 3-in-1, sewing machine oil or something similar is usually the best to use for this, if the bushings are already worn then a heavier oil like automotive engine oil can work better. If old oil has gummed up you may need to find a way to clean it out and re-impregnate the bushings with new oil.

I've tried a few times to rebuild motors like this by replacing the bushings with ball bearings and have had only limited success, it's mechanically tricky to install a ball bearing in place of the old bushings which are often spherical on the outside and fit into a spring clip rather than being pressed into a machined opening the way a ball bearing is. With some creative machining anything is possible but unless you are set up to do this it's probably not worth it.

[Fratink]

Marvel Mystery Oil

I will indeed Marvel at the Mystery of this Oil. 

Why is it mysterious?

[Dundarave]

Not to be overly discouraging, but over the course of my adult life, including as an office equipment technician during the 70’s and 80’s, I have never once successfully repaired (for any length of time over a day or two) any synchronous fan motors with gummed-up Oilite bearings.

I’ve never tried new capacitors, mind you, but after careful cleaning and oiling with the lightest quality oil, those damned things just refused to spin freely enough to work properly.

I remember that we used to use a precision reamer when installing new Oilites in our office equipment, so perhaps something like that might do the trick.

But I’ve simply given up trying now:  when a fan starts slowing down after a few years, I just spend $30 and buy a new one.  For me, anyway, its always ended up a waste of time to disassemble, clean, reassemble, and then toss out the damn thing anyway.

[Fratink]

Not to be overly discouraging, but over the course of my adult life, including as an office equipment technician during the 70’s and 80’s, I have never once successfully repaired (for any length of time over a day or two) any synchronous fan motors with gummed-up Oilite bearings.

I’ve never tried new capacitors, mind you, but after careful cleaning and oiling with the lightest quality oil, those damned things just refused to spin freely enough to work properly.

I remember that we used to use a precision reamer when installing new Oilites in our office equipment, so perhaps something like that might do the trick.

But I’ve simply given up trying now:  when a fan starts slowing down after a few years, I just spend $30 and buy a new one.  For me, anyway, its always ended up a waste of time to disassemble, clean, reassemble, and then toss out the damn thing anyway.

Yeah, if it wasn't for the fact that I can't stand throwing things away and that the company that made these wonderful fans closed up I wouldn't bother.  They're just such powerful and quiet fans that I'd hate to get rid of them.

As to reaming out the Oilites, the manual I found from a similar company actually says specifically that machining these oil impregnated bearings actually causes them to loose porosity. You'll probably be better off just replacing them as I can't imagine they cost much. 

[Gyro]

Yes, it's very easy to close the pores on Oilite bearings, either by clogging them, or by closing them with the surface 'wiping' action of a shaft running dry or a less than 100% sharp cutting tool.

[macboy]

Ball bearings may last a long time, but they tend be much noisier than bushings.

[Ian.M]

Ideally, Oilite and similar microporous bronzes should be machined with sharp single point tools, though it can be reamed with a sharp reamer, and should be re-impregnated after machining.  Any operation that burnishes or smears the surface reduces porosity, possibly critically, though slow single pass burnishing is recommended for final sizing when an extremely close tolerance is required (presumably the diameter increase is small enough that enough pores remain open).  Any use of abrasives, including lapping and grinding is forbidden as the abrasive residue will embed in the pores and cannot be effectively removed, resulting in the bearing lapping the shaft!

They've already been cleaned with scotch-brite - an abrasive - so are already FUBARed.  Might as well try to flush them and oil them properly to get them in usable condition, but long-term shaft wear will be an issue and it is either going to need machining down and undersize replacement bearings fitted, or the shaft could be sleeved and either oversized replacement bearings fitted to match or the existing bearings could be bored out to the sleeve size, which would also remove the abrasive contamination, and reimpregnated.

[David Hess]

As to reaming out the Oilites, the manual I found from a similar company actually says specifically that machining these oil impregnated bearings actually causes them to loose porosity.

A sharp tool is required to avoid smearing the pores closed.

[Ground_Loop]

Lubriplate 105

[andy3055]

Try Teflon grease:
https://tecratools.com/product630.html

[Fratink]

Ideally, Oilite and similar microporous bronzes should be machined with sharp single point tools, though it can be reamed with a sharp reamer, and should be re-impregnated after machining.  Any operation that burnishes or smears the surface reduces porosity, possibly critically, though slow single pass burnishing is recommended for final sizing when an extremely close tolerance is required (presumably the diameter increase is small enough that enough pores remain open).  Any use of abrasives, including lapping and grinding is forbidden as the abrasive residue will embed in the pores and cannot be effectively removed, resulting in the bearing lapping the shaft!

They've already been cleaned with scotch-brite - an abrasive - so are already FUBARed.  Might as well try to flush them and oil them properly to get them in usable condition, but long-term shaft wear will be an issue and it is either going to need machining down and undersize replacement bearings fitted, or the shaft could be sleeved and either oversized replacement bearings fitted to match or the existing bearings could be bored out to the sleeve size, which would also remove the abrasive contamination, and reimpregnated.

You are VERY correct about that.  Fan seized up after a couple days and the shaft was all scored up.  Lesson learned.

I used an ultrasonic cleaner and brake clean to clean them after this point, then used the ultrasonic to embed some 3in1 oil into the bushings afterwards.  On the not-FUBARed bushings it's made a HUGE difference, the fan is quiet and runs better than I've ever gotten it to run before.  The FUBARed fan is making a little noise, I'm not convinced it'll keep going.  It may become a parts donor now.  Lesson learned though.

Using the ultrasonic for cleaning seemed to work really well, as did oiling.  Those things get pretty warm so it worked to heat and agitate the oil into the bushing.  We'll see how long it lasts.