MadModder
Gallery, Projects and General => How do I?? => Topic started by: PekkaNF on June 29, 2017, 06:47:21 AM
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Situation is like this: I can buy just the right bearing, but it has wrong lubricant and wrong amount of it. I.E. I want low friction sealed bearing with very little high rpm grease.
Industry would just spesify the bearing, seal and grease and order a pallet load of them.
In priciple it is easy: Pop out the seal, wash and a dab of correct lubricant. Wrong. All has to be very clean and I have tried some mildly high speed (like hand routers) stuff and the rubber seal never goes back as good as original. It might look fine, but the lip rubs and generates heat.
This how-to-not:
Although this is interesting:
Starting from new design I could use one sided seal and arrange sealing othervise or put two back to back.
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Could you use a hypodermic needle with some solvent to flush the old grease out? Through the rubber seal. Id think it would self-heal sufficiently. Then either inject the new lubricant, or maybe try that vacuum approach.. Hard to control the amount that way though.
Russ
-russ
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Some people make a business out of it...http://www.smbbearings.com/products/bearing-relubrication.html (http://www.smbbearings.com/products/bearing-relubrication.html)
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Actually I have heard of that sort of services, that looks pretty specialized. I have heard some cases of a pallet of bearings nearing self life filled with fresh grease and sold. Don't knew if they went on agricultural or consumer stuff or just sold wheere ever.
Anyways, have been working with Ford focus 2006 pissing off cooloant from core plugs - at cylinder head between sparkplugs.
I might need to test this one soon or maybe I get lucky and find the appropriate bearing from the self.
Pekka
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I've never tried, but is it not possible to ease the rubber seals out of a bearing and then re-fit them? I would have thought that is was :scratch:
In which case just flush the bearing with the solvent of your choice (I'd use a WD40 or brake cleaner spray) then re-lube as needed
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Here you go, looks easy enough:
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I have done this very frequently over the last thirty years. I discover how little grease there were in bearings with seals when I worked with an auto electrician in Toulouse. My colleague systematically took the seal of alternator bearings and repacked them.
Never had any trouble doing this!
Regards, Matthew
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RS sealings come out and are easily pressed back easy too. However I only had good degree of success on low rpm application. Whenever I tried this to low friction type seal it did not work that well. They look the same than RS seal, but often are harder material and they should nor rub. Bit like plastic version of Z (dust seal). Got some one sided RS and Z bearing on last batch, have some time to experiment.
Pekka
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The 2RS seals on my bike bearings come out no probs for a quick flush and a squirt of new grease. I use a scalpel to pop them out but they are only small-ish ones like 6000, 6001.
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Have you checked if you can get brand new replacement seals? You might have better luck getting a new one back into place.
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A common mistake is to over pack bearings with grease. The manufacturer will usually publish the proper amount of grease for a particular bearing.
For a general rule of thumb (from a SKF web site);
"Super-precision bearings operating at high speeds should have less than 30% of the free space in the bearings filled with grease...
Open angular contact thrust ball bearings for screw drives should be lubricated with a grease quantity that fills ~ 25 to 35% of the free space in the bearing...
Sealed bearings are filled with a high grade, low viscosity grease that fills ~ 15% of the free space in the bearing. They are considered to be relubrication-free under normal operating conditions..."
If packed with too much grease they will run hot (not enough room for the balls to rotate freely).
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Yes, you can easily remove the seals with a sharp point like a compass or jewellers screwdriver.. Sorry, but regardless of what the manufacturers say, I don't go for underfilling bearings. On electric motors, in the day when they had grease nipples, we would clean the nipple, remove a plug from the lower part of the bearing housing, and pump with grease to force out all the old grease, and keep poumping till new grease appeared at the plug hole. This meant that due to the design of the bearing housing, the bearing was 100% full. . Brook motors used SKF bearings, and these were fitted as new equipment. We never had a bearing failure unless the grease was the wrong grade, or contaminated. Some of the motors I rebuilt had done 35 years operating in the clean conditions of a powdered milk plant, and even after this extended life, which included daily maintenance, the bearings were still servicable. Less grease = more sales!! The sealed for life bearing usually has a life of 5 years or less!
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I totally agree. I have a side business rebuilding electric motors,alternators and starters . And I never let a job go out of the shop without filling the bearings. Just remove seal and fill with a good quality grease and replace seal. I have never had a job come back where any f my bearings have failed. (just saying) My father-in-law owned the business before me and I bought it from him as a little side line cash generator and he will say the same and he was in the line of work for 60+ years! So I'll trust him and continue to do the same.
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Probably not pertaining to your problem. Had obsolete water-cooled engine with cooling fan on a stub-axle, identified a whine one morning when checking oil. The whine turned out being a double roller with shaft, that had metal seals. Being in a hurry to get the machine up and running (grader), I took the bearing (still in casting and being imperial) and boiled it in some grease, not the synthetic grade after I cleaned it with a cloth. The bearing saturated with grease and lasted until the replacement arrived.
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Had the repair a 1/2" Router today bottom bearing screeming , took it apart to get the size of the bearing , poped the seal no grease but some sticky dust , cleaned and filled with grease jobs a good un , I was going to buy a new bearing .