Measure the size of the shaft and the SKF bearing seat hole to determine the matching accuracy of the SKF bearing. The matching requirements are as follows: the inner ring and the shaft adopt an interference fit, and the interference is 0 ~ +4 μm (at light load and high precision, it is 0); the outer ring and the SKF bearing seat hole adopt clearance fit, the clearance amount is 0~+6μm (but when the bearing at the free end uses angular contact ball bearing, the clearance can also be increased); the roundness error of the shaft and the seat hole surface is 2μm Below, the end face parallelism of spacers used in SKF bearings is less than 2 μm, the runout of the inner end of the shaft shoulder to the outer end face is less than 2 μm; the runout of the shoulder of the SKF bearing housing hole to the axis is less than 4 μm; Beat below 4μm.