Abstract
The purpose of this paper is to bring out methods of lubrication especially suitable for speeds of 4000 to 7500 r.p.m. which is about the range of woodworking spindles.
The author sums up by stating that where oil is used its level should not be over the center of the lowest ball if speeds are higher than 500 r.p.m. At 5000 to 5700 r.p.m. a very light spindle oil should be used, and it should be fed either by wick, or circulation from pump as any depth of oil around the balls will cause tremendous churning. Too much oil should not be used as it will cause heating, and the higher the speed the greater the heat.
If grease of the proper consistency is used, the housing can be filled. At high speed there will be a path cut through the grease by the balls, and if temperature develops, just enough melting will occur to furnish the lubrication required. Greases soft enough to churn should be avoided for high-speed applications as the heat generated will melt them so fast that conditions will duplicate those of too much oil. Failure is generally due to dirt, so the bearings must be kept clean. Especial care should be taken in renewing the lubricant, as this is when most of the dirt gets in.
