Chuck Jaws Ground In Place On Machine
This method of holding is good, however, it is limited. It is true that the chuck jaws will compensate for some of the taper, however, in the case of a bulging, only line contact can be obtained, thereby allowing possible distortion of the part within the chuck jaws. Also the chuck jaws may not compensate for all of the taper, thereby again giving line contact.
Diaphragm-type Chucks Ground On Machine
This method again produces a check with a surface that will indicate as true as the machine spindle will run. However, since the grinding must be done at some specific diameter, usually the mean dimension, perfect chucking will only take place on parts whose diameter just happens to be that to which the chuck was ground. Due to the arc of travel of this type chuck, all other parts will be chucked with line contact and not total surface contact. If chucking pressures are increased so as to distort the diaphragm to get total surface, then they may also distort the part due to the excessive pressure.