- Joined
- Dec 21, 2018
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- 1,815
Always use the same reference point when measuring end play, I.E. Don't rotate the shaft. Snug the nut on the thrust bearing (end of shaft) until you get no movement in the axial direction when pushing/pulling on shaft. A wee more tightness on the nut won't hurt and will provide some preload. I don't think those machines were built with tapered roller bearings on the chuck end. So, your only option there is how good the existing bearing is. Put a bar in the chuck, big enough not to have any bar flex when you pull up & down or side to side. W/O rotating the shaft put your test indicator on the side of the shaft and push on the shaft. The further away from the bearing the more movement you will see. Where that play is coming from depends. Is the fit of the shaft in the bearing snug, slight press fit? Ideally no movement. Is the fit of the bearing in the housing snug? Ideally no clearance but not a press fit. Is the chuck fully seated? Is the chuck so bell mouthed that the bar in it can be pushed side to side in it?
About ball bearings: As they run @ design speed they will reach design operating temperature and expand slightly taking up design clearances. Those aren't much and for your purpose on a slow rotating machine like a manual lathe the class of bearing fit should be fairly tight to start with. Bearings that are grease lubed should not be fully packed with grease as that will make them run hotter. High speed, heavily loaded bearings will have a looser initial fit until they reach design temperature. Tapered roller bearings eliminate most of these issues by using a set of two matched bearings arranged so they push against each other's cup sides by squeezing with some means of applying flexible loading. Commonly cupped fingered spring washers. Bearings used this way should always be kept as the matched sets, as sold by the factory. The design engineers of the machine will have determined the correct preload required and used the correct method of loading. Virtually no play will exist. Everything has some flex!
About ball bearings: As they run @ design speed they will reach design operating temperature and expand slightly taking up design clearances. Those aren't much and for your purpose on a slow rotating machine like a manual lathe the class of bearing fit should be fairly tight to start with. Bearings that are grease lubed should not be fully packed with grease as that will make them run hotter. High speed, heavily loaded bearings will have a looser initial fit until they reach design temperature. Tapered roller bearings eliminate most of these issues by using a set of two matched bearings arranged so they push against each other's cup sides by squeezing with some means of applying flexible loading. Commonly cupped fingered spring washers. Bearings used this way should always be kept as the matched sets, as sold by the factory. The design engineers of the machine will have determined the correct preload required and used the correct method of loading. Virtually no play will exist. Everything has some flex!