7. Other milling factors

7.1 Effect of spindle inclination

Some milling machines have a spindle slightly inclined in the feed direction to prevent the milling cutter from lying flat against the workpiece (figure 49 ). This inclination (q ), which may be around 0.1 mm per 1,000 mm, is essentially designed to prevent the cutter from dragging, which would damage the surface finish by leaving more or less deep marks, in the opposite direction to the normal feed. Machining centers and other multi-operation machines often do not allow the spindle to be tilted, so backfilling is usually unavoidable. Even if the spindle is tilted correctly, there may still be problems with heeling due to bending of the spindle or the workpiece. This...