Gene Davis
07-11-2002 06:50:12
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Re: Re-Metaling of bearings and bushes with white metal in reply to Cliff Tyson, 07-03-2002 11:05:49
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Used to work at a machine shop years ago and we repoired bearings for sawmill shafts this way. We melted out old bearing material (babbit,the more tin in the babbit the higher speed raring on the bearing), then we cleaned the housing,roughened it up slightly for the babbit to adhere to. We had short pieces of the correct diameter shaft that we used to get the correct inside diameter of the bearing. We took the shaft and completly covered it with a layer of sooty residue from the acwtylene torch burning acetylene with very little or no oxygen, you could probably use lamp smut, what you are doing is creating some to keep the high temp metal from bonding to the shaft, most oils and grease will burn and contaminate the mix, we had best results from smutting the shaft. We placed an equal number of shims on each side of the bearing half to allow it to be removed to take up some of the wear after the bearing ran for a while. You need to make sure there is NO Moisture, as moisture causes the metal to spit back violently!! We then built a fire proof dam on one end of the housing,don't know what to tell you to use here, since we used asbestos material at that time,(been45yrs. We usually stood the bearing on end when ever possible, to pour it easier. The beaing metal, or babbit as it was called here is melted in a cauldorn or a ladle over heat and skimmed to remove all impuruties ,you do not want to have a roaring fire, just steady heat that is hot enough to melt the metal, spatters of this will cause TERRIBLE burns, be sure that no moisture or oil gets int othe metal. It is important to remember that once you start pouring that you have enough bearing metal to pour the complete bearing non-stop, or else you will not get a soild bearing, every time you interrupt it the bearing becomed layered, or worse has air pockets in ot and the metal is not solid in the bearing. Keep pouring slowly till the metal fills up the housing and over flows slightly, let cool to the touch, then disassemble, keeping shims in the right, remove the sizing shaft piece,trim the excess bearing material off ends and sides ,drill the necessary lubricating holes, or in some cases oil grooves. The bearing should be ready to re install. Hope this helps Gene Davis Tennille Ga. U.S.A.
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