A. principal axis of ellipse is directly reflected in the work up, if the sliding bearings, so when the same size and the direction of load, shaft under load is pressed in a certain position on the bearing surface (due to the gap between the spindle and the bearing). When the main shaft rotates 90 DEG, the center shaft changes, so that the spindle two center position during rotation process, cutting depth, tool change, and make the workpiece roundness. Bearing hole ellipticity on the workpiece does not affect.
B. stock is not uniform, and between the shaft and the bearing clearance, the cutting depth changes in cutting process.
C. before and after the center hole doesn't agree with (two center hole and the center of an angle), center hole and a top contact only to one side, uneven wear caused by axial shifting Cheng Tuoyuan D. front tip swinging. 2 bus is not straight (Yu Song, convex, saddle) and the taper of the reasons
A. lathe slideways and spindle center line position is not correct, especially at the level of. As the guide rail bending, workpiece is convex or concave, slideways and spindle center line does not parallel cone etc..
Before and after the B. line and the bed top center side rail is not parallel, the taper.
C. artifacts due to temperature rise, will make the shaft bending. For example, in heavy lathe machining axis, the temperature rises to a certain time, the workpiece will stretch, but because the two top distance unchanged, the workpiece due to the inability of elongation in the length direction and bending. Therefore, in the car long axis, as far as possible to reduce the temperature, but also often have to return after the top.