【转帖】axis control

yang686526

axis control
do all axis controls, such as perpendicularity and parallelism of holes, get measured by using median points orignated from the feature surface just like concentricity of holes?
in other words, if total runout is prefered when specifying concentiricity because of difficulties in measuring the axis, then that idea applies to all axis control??
thank you,
uka
no they don't.
if one was using a coordinate measuring machine, one would take various points perpendicular to the axis and the equipment would give them the center. this would then be compared to the tolerance. this method would give about a 90 - 95% confidence since we have eliminated the roundness and size of the hole
if i did not have a cmm, then i would check the entrance of the hole and the bottom using an indicator and then the hole exit once i set the hole on the "true" angle. unfortunately, this method used in a tool shop is suceptible to the influence of roundness and diameter differences. it is only a 80% method as most.
dd