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11-10-2010, 04:09 AM #1
OT- re-lubricating an oilite bearing
The only reason why I classified this as OT is that it is a bearing on a bread maker. I'm sure there are other applications for this knowledge. I have a bronze oilite bearing in a bread maker that is seizing up on the shaft. It is not "worn out" or anything, it just needs to be re lubed. After years of the cooking heat and cleaning, it has lost the oil in it. I took the c clip off the shaft and pulled it from the bearing. I then soaked the bearing in high temperature silicone oil which is good for 300C and let it sit for a few minutes (this is the oil used in a vacuum diffusion pump). This oil should certainly be good to go heat wise. My wife used it about a dozen times and then the shaft froze up again. I think my problem is that I need to somehow infuse oil back into the bearing better. I do not know how to do this other then just soaking it (something I really didn't do for very long the first time). Does anyone know of a better method. Pressure, vacuum, boiling in oil etc.? I could make another one but I don't want to if I don't have to. I have plenty of bronze bearing material but I don't think it is oilite. Thanks for any help.
11-10-2010, 04:30 AM #2
I would remove the bushing and heat it up red hot with a torch and burn all the residue out of it. As soon as it stops smoking, its done, and let it cool down to about 500° and dunk it in new oil, in hopes that the new oil will infuse into the now empty porous structure.
11-10-2010, 04:39 AM #3
11-10-2010, 04:43 AM #4
Clear out the bearing of old oil, burn out if necessary, but that may leave carbon in the pores. I don't know of a much better way, though.
Plonk it in new oil of the right type, covering it, and pull a vacuum on it..... wait for it to stop bubbling or fizzing, then release the vacuum. A brake bleeder pump may be enough.
BTW, I don't think silicone oil is good for it.... That oil IIRC does not change viscosity much with heat, and I believe the issue is that the oilite (a trademark, btw) lets the oil out into the bearing space when it warms, and sucks it back in when it cools... That depends a bit on a viscosity change, I'd think.
11-10-2010, 04:45 AM #5
Most likely an off the shelf size available from your local bearing store. If the bearing is dry it's possible that the oil has coked up and blocked the pores. Probably putting the bearing in a small container of oil in a vucuum chamber would be your best shot at a relube...............Bob
11-10-2010, 05:11 AM #6
If this bearing is a standard size it might be prudent to go to the local hardware store
and buy a new Oilite bushing for little money and replace it. Seems easier than trying to
11-10-2010, 05:16 AM #7
If the bushing is the one that I think it is, it might be in contact with foodstuff, so probably a mineral oil might be better than the unknown lubricant in general purpose Oilite? I don't know, but it might make the difference between that first loaf being a keeper or not
11-10-2010, 05:36 AM #8
I do not understand why a vacumn would put oil in. I would pull a vacumn to remove the old oil. Then I would put it in a piece of pipe. capped at one end Hold the pipe vertical add enough oil to submerge it then cap the open end. add air to say 50-100 PSI and let sit overnight.
maybe run it through a ultrasonic cleaner first
11-10-2010, 05:54 AM #9
Vacuum pulls air out. Nature abhors a vacuum so oil goes in.................Bob
11-10-2010, 06:02 AM #10
Wouldn't the oil be pulled into the pours when the vacuum is released. I made a bunch of stuff for a PlasmaBond process. Pull an massive vacuum on reactor studs,(prone to gauling) then induce a current through gold. Turned the gold into a vapor that was sucked into the pours of the reactor studs. I guess its the same principle.
11-10-2010, 06:28 AM #11
11-10-2010, 06:58 AM #12
An outfit I used to work for did this regularly. They'd bake the part to release the original lube, then vacuum impregnate with the new lube, like was previously posted. Don't burn out the old lube, it'll close up the pores.
If the bushing is a standard size, it may be cheaper to replace it.
11-10-2010, 07:01 AM #13
you might also try hosing it out with crc red brakleener, it might clear the old oil and residue from the pores.
it works well to get the sediment out of those old gm rock fuel filters used in their carbs.
couldn't hurt to try prior to a burnout process.
ps. don't breathe the fumes because it gives off some nasty cancer causing compound
if it isn't fully dried out first.
11-10-2010, 08:59 AM #14
I found an interesting read on the invention of Oilite.
Oilite bearings and the Chrysler Amplex Division
Sounds like it should be safe to heat it as hot as it would take the tin to melt and not hotter. So not red hot, I guess, although I have done it a couple of times and it worked ok.....I did not loose the bushing or change its dimension. They say 1.5% graphite was used in the mix, so a little carbon residue is probably not going to hurt anything or close up the pores. When its hot, the oil is busy just hustling outta there
11-10-2010, 10:13 AM #15
If it is small enough you can place it on your thumb, fill it with oil then place another finger on top und squeeze the new oil through
The oil will sort of sweat throug to the outside If it does so evenly the bearing is OK
Repeat a couple of times till you get clear oil sweating through
With bigger bearings you can do similar between the mouses of your hands
Wear rubber gloves if you don`t want your hands dirty
Peter from Holland
11-10-2010, 10:48 AM #16
Well you guys have certainly given me some good things to try. This is a very low speed device so I don't think things are going to get out of hand if I am not completely successful. Of all the suggestions I kind of like the one where I would fill it up with oil and pressurize it to see if I could get oil to flow through the pores. I do have high vacuum equipment so if that doesn't work then I will try pulling a vacuum on it under a bell jar submersed in oil and then release the vacuum. I know I could probably buy a new one but it just chaps my ass to not be able to fix something like this. I have thousands of dollars worth of machinery at my disposal and I should be able to do this. It certainly is not a money thing...it's a "I can fix anything but a broken heart" thing. This kind of thinking has gotten me in WAY over my head before and I expect this trend to continue. Thanks very much for all your ideas. I will let you guys know what works if it does. It seems like a useful skill to have.
11-10-2010, 10:52 AM #17
I researched this years ago and peterve's suggestion was the one I found, I don't remember where
Although I'm not sure about the "mouses" bit
SAE 30 was the oil of choice IIRC.
11-10-2010, 11:03 AM #18
Three things keep new oil out.
1) Air/water/other non-oil stuff in the voids
2) Old oil in the voids
3) Viscosity and surface tension of the new oil
I would use a cyclic application of vacuum in a bath of warm oil. If you really feel the need to remove the old oil, preceded this with cyclic application of vacuum in a bath of mineral spirits might be best.
The vacuum pulls air out. When the vacuum is decreased, atmospheric pressure pushes the warm oil in. Higher temperature reduces viscosity and surface tension of both old and new oil.
But if the bearing is seizing up, couldn't this indicate that the voids in the bearing have sealed up, either by physical compaction or by the old oil getting sludgey? Why not buy a new bearing?
11-10-2010, 07:10 PM #19
Ha ha Peter (from Holland) you beat me to describe the ONLY way to charge a sintered bronze or iron bearing. Why anyone would go to more trouble to achieve less is beyond me. It's quite satisfying to see the froth come out of a new sleeve before the ooze of clean oil, when you KNOW the sleeve is fully charged. BTW I think you meant 'palms'.
11-11-2010, 12:27 AM #20