Depth of a Counterbored Hole 1

[superptrucker]

If the depth of a counterbored hole in the top face of a plate is directly toleranced, what is the proper way to measure the depth? Is it to a tangent plane established by the top face of the plate or would it be more localized e.g. measuring the depth with the tail end of a caliper? According to the standard, for countersunk holes, the depth is determined by the creation of the countersunk diameter so even if the plate was warped the depth of a number of countersunk holes would follow suit. Fig. 1-40 shows countersink on a Curved Surface. Since the purpose is usually to sink a fastener into the plate, I'm wondering if something similar applies to counterbored holes. I guess the same could be asked for drilled, counterdrilled holes, and spotface depth also.

 

[Burunduk]

if there is any question about whether sufficient margin between the washer or head diameter of the fastener and the diameter of the planar surface at the base of the counterbore I would also want it measured as for a spotface, where probably a vision system is used to measure the diameter of the planar surface at the difficult to identify tangent line with the fillet radius. As with all measurements there is uncertainty to deal with, but this measurement may be very important to ensure that the fastener will seat properly.

If a similar question arises about a spotface, it may arise not only due to the diameter of the spotface but also due to its out-of centering relative to the hole. Do you have a suggestion on how to control the centering of a very shallow spotface relative to the hole? I opened a thread about it a while back: thread1103-474434. Some good suggestions were given, however, I'm still wondering whether there are ways to locate a spotface that doesn't have a cylindrical portion (or even a fully formed fillet radius), or any other type of very shallow recess for that matter, that don't involve sinking the feature deeper and making it into a counterbore/fully formed pocket or specifying a wordy note to describe the location requirement.

I will appreciate your response either here or on the older thread on that topic.